Predatory attacks by snakes on nesting birds and their offspring have been well-documented globally (for example, in Africa: Lloyd 2004, mainland Asia: Khamcha et al. 2018, Australia: Fulton 2018, North America: DeGregorio et al. 2014, and the Neotropics: Menezes and Marini. 2017). However, while many species of snakes are known consumers of nestling birds, chicks, and brooding adults, few species are reported consuming bird eggs. Predation of eggs by snakes can reduce recruitment of birds and impact bird population dynamics (Lavers et al. 2010). In addition, by preying on eggs, snakes have the potential to influence bird life history patterns by forcing them to re-lay and brood successive clutches (DeGregorio et al. 2014). Given that many species of birds provide important ecosystem services (Whelan et al. 2008, Whelan et al. 2015, Şekercioğlu et al. 2016), population fluctuations from reduced recruitment could potentially alter the functional integrity of a range of ecosystems (Mortensen et al. 2008, Gascon et al. 2015, Lowney and Thomson 2021). For example, extensive predation on birds and eggs by invasive brown tree snakes (Boiga irregularis) on the islands of Guam has fundamentally altered the local faunal community through extirpation of several species, ultimately causing trophic collapse (Wiles et al. 2003). Thus, by preying on bird eggs in large numbers, snakes have the potential to indirectly influence ecosystem functioning in many biological communities.
Quantifying the extent to which snakes affect ecosystems by consuming bird eggs is hindered by numerous challenges. Several facets of these trophic interactions are unclear, including knowledge of which species of birds lay eggs that are at risk of snake predation, as well as the extent to which predation of bird eggs by snakes varies spatiotemporally (Weatherhead and Blouin-Demers 2004, Lahti 2009, Menezes and Marini 2017). Identification of which snakes consume bird eggs offers a critical first step in understanding these dynamics. Knowing which species of snakes consume eggs allows researchers to formulate predator-specific hypotheses across a range of habitats and environments (Reidy and Thompson 2012, Ibáñez-Álamo et al. 2015). Additionally, avian conservation practitioners can use that information to produce anti-predator strategies for bird conservation efforts. Unfortunately, information on snake feeding is poorly catalogued (Grundler 2020, Maritz et al. 2021b) making the compilation of a robust list of oophagous species challenging.
Snake diets are diverse, compositionally complex, and often difficult to adequately quantify (Greene 1997, Glaudas et al. 2017, Maritz and Maritz 2020). Unfortunately, the natural history data required to systematically describe snake diets are often lacking, particularly for taxa that occur in poorly-studied regions. For most species, we know very little about their feeding habits apart from generalized characterisations of their diets inferred from a limited quantity of published information (Maritz et al. 2021b). For many others, we lack even a basic understanding of their feeding habits. A recent global synthesis of snake feeding records by Grundler (2020) highlights the incomplete nature of our understanding of snake diets. Of the 3921 species of snakes distributed across the globe (Uetz et al. 2021), less than a third (1248 species) could be included in that dataset and the majority of those species were only represented by fewer than ten records. Due to this paucity of feeding records, our understanding of which types of prey are, or are not eaten by different species of snakes is limited. Consequently, many species of snakes not currently known to eat bird eggs may be oophagous.
Despite the above limitations, published records of snakes consuming bird eggs have accumulated in the literature (Weatherhead and Blouin-Demers 2004, Ibáñez-Álamo et al. 2015). Over the past few decades, using camera monitoring systems, some snake species have been documented eating eggs for the first time (Cutler and Swann 1999, Pierce and Pobprasert 2007, Ribic et al. 2012, Khamcha et al. 2018). Moreover, novel feeding records published in natural history publications and online community science portals continue to confirm additional species as bird egg predators. However, because studies and platforms vary in their objectives, records are scattered in the literature and online. In some cases, reports may be difficult to access or are completely inaccessible to researchers or conservationists interested in using such data.
We compiled a comprehensive list of confirmed snake predators of bird eggs. We collated records of snakes consuming bird eggs from a range of sources of information and used the details within those reports to broadly summarize trends of bird egg predation by snakes globally. We also analysed several traits of the identified snake species and egg prey to test hypotheses regarding why those species consume bird eggs but many others do not. Specifically, we tested if the inclusion or exclusion of bird eggs in the diets of snakes is associated with 1) differences in snake body size, 2) variation in snake habitat use, and 3) taxonomic relatedness between snake taxa. To contextualize which bird species are at risk, we also compared the size distribution of consumed bird eggs to that of a sample of bird eggs not reported in the diets of snakes. Lastly, we investigated the sizes of eggs consumed by snakes of varying body lengths.
Between August 2020 and July 2021, we searched for and collected data from reports of bird egg predation by snakes. Our main sources of data were formal publications (i.e., peer-reviewed journal articles and books) found on the online indexer Google Scholar, JSTOR, and SquamataBase (Grundler 2020) - an online natural history repository containing close to 11,000 records of predator-prey interactions across 1248 snake species. We also searched the literature cited within those publications to identify additional sources. Additionally, we collected data from unpublished academic theses and personal communications from researchers. Lastly, we collected data from community science records published on the online platform iNaturalist (https://www.inaturalist.org) and the social media network Facebook. Facebook records were obtained from the groups “Predation records - reptiles and amphibians (sub-Saharan Africa)” (published in Maritz and Maritz 2020), “Snakes of South Africa” (https://www.facebook.com/groups/snakesofsouthafrica), and “Wild snake predation records” (https://www.facebook.com/groups/wild.snake.predation.records).
We restricted our data collection to include records of snakes unambiguously eating bird eggs. We did not include reports with vague descriptions of snakes attacking nests unless eggs were directly specified as the prey rather than nestlings, chicks, or adult birds. Conservatively, we excluded records without clear evidence of snakes eating eggs. For a record of a snake species to be included it needed to meet these criteria: 1) snakes were observed eating, attempting to eat, or having eaten (shells in digestive tracts) eggs and 2) records were of snakes in the wild consuming eggs they found without human intervention. We included cases in which the eggs of captive or domesticated birds were consumed if those predatory attacks met the above criteria.
For each reported predation event, we identified the snake and bird species to the finest taxonomic level possible, and we noted the number of eggs involved. Geographic coordinates were noted from the original record or estimated using Google Maps. We updated snake species names to match their current taxonomic nomenclature as per Uetz et al. (2021). We provide a summary of these records detailing the taxonomic diversity of oophagous snake predators and their bird egg prey, as well as geographic biases in these trends.
Although the primary goal of this study was to compile a list of known snake predators of bird eggs, we were also interested in examining traits of those species that might explain why those snakes consume bird eggs but others do not. Differential prey use within a particular snake species is facilitated by several factors, chief among which include varying body size constraints (Arnold 1993, Greene 1997, Maritz and Alexander 2014) and variable encounter rates of different prey (Alencar et al. 2013, Mori and Nagata 2016). Accordingly, we chose to examine and compare the body lengths and primary habitats of the snakes on our list to snakes not known to consume bird eggs. Snake body lengths correlate with their diet breadth as larger snakes can typically consume bulkier and heavier prey than smaller ones, and can therefore hunt a broader range of prey (Arnold 1993, Maritz et al. 2021c, Barends and Maritz 2022). Habitat use largely influences the probabilities at which snakes encounter different prey (for example, arboreal snakes are more likely to encounter arboreal prey; Harrington et al. 2018). Taken together, these traits are likely major limiting factors towards bird egg consumption by snakes.
Unfortunately, most accounts of snakes consuming bird eggs do not include linear measurements of the sizes of the individual snakes in question. To compensate for this, we instead used maximum body length data (i.e., length from snout to tail) of each species on our list (Electronic dataset 1) collected from Feldman et al. (2016). We also collected these data for all other species in the Feldman et al. (2016) dataset (N = 3529) for use in comparisons (Electronic dataset 2). Similarly, we gathered information on snake habitats to classify species as either aquatic, arboreal, fossorial, semi-arboreal, or terrestrial. We gathered these data for as many species as we could (N = 2646) from field guides and published datasets, including Pizzatto et al. (2007), Lawing et al. (2012), Feldman and Meiri (2014), Bars-Closel et al. (2017), Cyriac and Kodandaramaiah (2018), and Harrington et al. (2018).
We were similarly interested in examining traits of the consumed bird eggs that could provide insight into which bird eggs are at risk of predation by snakes. Because prey bulk (i.e., the cross sectional-diameter of prey) relative to snake size is an important consideration of dietary selectivity in snakes (Greene 1997) we chose to quantify the diameters of consumed eggs. Snakes typically ingest bird eggs length-wise (Gans 1952), and so the diameter of the eggs acts as the main dimensional constraint on ingestion. However, as before, most reports did not include measurements of the dimensions of the eggs consumed. We thus gathered information on average egg diameters for each of the bird species on our list (Electronic dataset 1). We gathered these data from resources detailing the reproductive traits of birds that breed in Australia (Garnett et al. 2015), Asia (Tsai et al. 2020), Britain and Europe (Harrison and Castell 2002, Storchová and Hořák 2018), Micronesia (Brandt 1962), North America (Baicich and Harrison 2005), South America (Mason 1985, Auer et al. 2007, Marques-Santos et al. 2015), and southern Africa (Tarboton 2011). For comparative purposes, we also gathered egg diameter data for a geographically and phylogenetically diverse sample of 2326 species of birds (~25% of all birds; Electronic dataset 2).
We analysed geographical trends of bird egg predation by snakes by comparing the numbers of 1) feeding records, 2) identified snake species and 3) identified bird egg prey species across major geographical regions. We demarcated regions as Africa, Asia, Australia, Central America, Europe, Micronesia, the Middle East, North America, and South America. We also examined the elevation (in metres above sea level) of each area where predation events were observed. We gathered elevation data where predation events occured (N = 350) at a resolution of 30 arc seconds from the Worldclim global elevation dataset (Fick and Hijmans 2017).
We evaluated the ecological traits of oophagous snakes by first analysing patterns of their body length distributions. We used a Kolmogorov-Smirnov test to compare the relative distribution of the maximum body lengths of oophagous snakes to all snakes included in Feldman et al. (2016). We then used a phylogenetic ANOVA to test for differences in average log-transformed maximum body lengths of snakes that do and do not consume bird eggs while accounting for the effects of phylogenetic autocorrelation caused by species relatedness. We performed this test with the "Geiger" package (Pennell et al. 2014) in R software v.4.1.1 (R Core Team 2021) using a pruned version of the phylogeny of squamate reptiles published by Tonini et al. (2016) (N = 3503 species) as the input phylogenetic tree. We similarly summarized oophagous snake habitat use and then compared body lengths (log10 transformed) by habitat use controlling for phylogeny via phylogenetic ANOVA.
We tested for the presence of a phylogenetic signal associated with bird egg consumption by snakes by calculating Blomberg’s K (Blomberg et al. 2003). We considered a Blomberg’s K value less than one to indicate that oophagy occurs randomly across our tree under Brownian motion evolution whereas K values greater than one suggest oophagy is more prevalent between closely related snake taxa (Blomberg et al. 2003). We performed this test using the "Phytools" package (Revell 2012) in R.
Similar to our analyses of snake body lengths, we performed the same comparative tests between consumed eggs and other eggs. We used a Kolmogorov-Smirnov test to compare the relative distributions of egg diameters of eggs eaten by snakes and all other eggs. We then looked for differences in average log-transformed diameters of consumed eggs and other eggs (N = 2326) via phylogenetic ANOVA. We used a pruned version of the phylogeny of extant birds published by Jetz et al. (2012) as the input tree for this test. Finally, we visually inspected the relationship between bird egg diameters and snake body lengths across all predation events by creating a Sankey plot depicting the flow between egg diameters (in mm) and snake length (in meters). For bird egg diameter size classes, we used bins of 10 mm, and for snake body length size classes we used bins of 1 m.
Our search produced a total of 471 records of confirmed predatory interactions between snakes and bird eggs across the globe (Table 1). Bird eggs were consumed by 123 different snake taxa (114 species and nine subspecies) belonging to 59 genera and seven families (Boidae, Colubridae, Elapidae, Psammophiidae, Pseudaspididae, Pythonidae, and Viperidae). Of these, Colubridae (70% of all 123 taxa) and Elapidae (13% of all 123 taxa) were most frequently reported (Fig. 1). The eggs of at least 210 species of birds across 159 genera, 71 families and 21 orders, including passerines and several non-passerine orders, were consumed. In 26 cases, bird eggs were only identified to genus, family, or order levels (seven cases, 14 cases, and five cases respectively). In 63 cases, bird eggs were not identified beyond the class level, or the exact identity of the species was ambiguously reported in the source material (for example, “the eggs of land birds”).
Predation of bird eggs by snakes was reported on all continents on which snakes are distributed as well as on several archipelagos and small islands (Fig. 2). The majority of these observations (~75%) occurred at low elevations < 500 m above sea level. Sampling frequencies of feeding records varied between geographical regions (Fig. 3) as most predation events were observed in North America (37% of all records) and Africa (24% of all records). At the national level, most records disproportionally represented the relatively well-studied United States of America (35% of all records) and South Africa (14% of all records) respectively. Species richness of snake predators and bird egg prey also both varied regionally and were similarly proportioned to the spread of predation records (Fig. 3). Approximately 29% of recorded snake predators were from North America, 20% from Asia, and 17% from Africa. Similarly, 31% of identified bird taxa whose eggs were consumed were from North America, and 23% were from Africa.
In Africa, the common egg-eater (Dasypeltis scabra), was responsible for most reports of egg-eating and was most reported for any snake species (N = 53, 11% of all records, Table 1). Common egg-eaters consumed the eggs of at least 40 species of birds throughout southern and East Africa, ranging from the southernmost regions of South Africa to Uganda. Other important oophagous African snakes included various species of cobras (Naja spp.), boomslang (Dispholidus typus), and mole snakes (Pseudaspis Cana) that were predominantly from southern Africa. Southern and East African pythons (Python natalensis and Python sebae) were also confirmed as bird egg consumers.
In North America, various rat snakes (Pantherophis spp.) were the principal consumers of bird eggs, collectively accounting for 15% of all records (Table1). Other frequently reported species included several species of bullsnakes (Pituophis spp.), kingsnakes (Lampropeltis spp.), and eastern racers (Coluber constrictor). Collectively, snakes from the above genera consumed the eggs of at least 66 species of bird across the USA (Fig. 2). In particular, these snakes were most frequently observed raiding hen-houses for the eggs of Domestic Chickens (Gallus gallus domesticus) and often consumed the eggs of Black-capped Vireos (Vireo atricapilla), Field Sparrows (Spizella pusilla), Northern Bobwhites (Colinus virginianus), and several species of ducks and geese. In Florida, the invasive Burmese python (Python bivittatus) consumed the eggs of Limpkins (Aramus guarauna), American White Ibises (Eudocimus albus), and introduced Helmeted Guinea Fowl (Numida meleagris). Other notable North American oophagous snakes included common garter snakes (Thamnophis sirtalis), eastern indigo snakes (Drymarchon couperi), and massasaugas (Sistrurus catenatus), the only viperid from North America included on our list.
Neotropical snakes from Central and South America that consumed bird eggs mostly included several species of colubrids (Table 1). Western indigo snakes (Drymarchon corais), several species of puffing snakes (Phrynonax spp.), and both species of chicken snakes (Spilotes pullatus and S. sulphureus) were the principal egg predators in these regions. Records involving those species were largely restricted to regions in Brazil and Peru but extended as far south as Chile and as far north as Costa Rica (Fig. 2). Collectively, Neotropical colubrids consumed the eggs of at least 20 species of birds. Large boas and anacondas of the genera Boa, Epicrates, and Eunectes were observed consuming the eggs of at least seven species of birds in various habitats in Brazil and Argentina. Similarly, in the Caribbean, several species of Antillean boas (Chilabothrus spp.) were notable bird egg predators.
In Europe, only five species of snakes were reported consuming bird eggs (Table 1). The most frequently reported species were the four-lined snake (Elaphe quatuorlineata) in Italy and the Montpellier snake (Malpolon monspessulanus) in Spain. The European adder (Vipera berus) in the United Kingdom, the Aesculapian snake (Zamenis longissimus) in Italy and Poland, and the ladder snake (Zamenis scalaris) in Spain were also confirmed as oophagous. Those snakes were frequently recorded consuming the eggs of Common Pheasant (Phasianus colchicus), Great Tit (Parus major), Common Linnet (Linaria cannabina), and Common Babbler (Argya caudata). We only found one record of bird egg predation in the Middle East which was of the Arabian tiger snake (Telescopus dhara).
Across the oceanic region of Asia, Australia, and Micronesia, cat snakes of the genus Boiga were the predominant bird egg predators. Records of these snakes accounted for 6% of our dataset (Table 1). More than half of those observations were of the invasive brown tree snake (Boiga irregularis; N = 16) on the island of Guam (Fig. 2). Predations by other cat snakes (B. cyanea, B. cynodon, B. dendrophilia, B. kraepelini, B. ochracea, and B. siamensis) were observed on several islands and coastal regions of South-East Asia. Asian rat snakes (Elaphe spp.) were important predators of bird eggs in habitats across China and offshore Japan. In India and surrounding areas, the bird egg specialist Indian egg-eater (Elachistodon westermanni) purportedly consumed the eggs of several species of birds similarly to African Dasypeltis. However, few feeding records for these snakes have been published. Lastly, while few observations were reported from Australia, at least two species of pythons (Liasus fuscus and Morelia spilota) and three species of elapid snakes (Denisonia devisi, Notechis scutatus, and Pseudechis australis) consumed bird eggs in this region.
Oophagous snakes averaged 2057 mm in maximum length, ranging by an order of magnitude in size from 600 mm (Denisonia devisi) to 6000 mm (Python bivittatus). However, most of these species ranged between 1500 mm to 2000 mm in maximum length. The distribution of maximum body lengths of oophagous snakes differed significantly from snakes in general (D = 0.671, P < 0.001; Fig 4.A). Oophagous snakes were significantly larger in maximum length on average compared to other snakes (Phylogenetic ANOVA: F1, 3501 = 307.322, P < 0.001). Body size thus appears to be an important component of bird egg consumption by snakes.
Most snake species in our list were terrestrial (60% of all 123 taxa) rather than semi-arboreal (21% of all 123 taxa) or arboreal (17% of all 123 taxa). Only two species (Laticauda colubrina and Thamnophis hammondii) were aquatic (~2% of all 123 species), and none of the species in our list was fossorial. We found no differences in the body sizes of snakes of differing habitats (Phylogenetic ANOVA: F3, 105 = 2.117, P = 0.339). Thus, differences in body size of oophagous and non-oophagous snakes are unlikely driven by differences in habitat use. Additionally, we found a low phylogenetic signal for oophagy in snakes (Blomberg’s K value of 0.065; P = 0.504), indicating that this trait evolves independently of phylogenetic relatedness.
Consumed bird eggs snakes ranged between 10 mm (Zebra Finch, Taeniopygia guttata) and 58 mm (Domestic Goose, Anser domesticus) in average diameter. Approximately 64% of the eggs consumed by snakes were on average narrower than the mean of this range (24.38 mm, back-transformed from log widths). Overall, the relative distribution of egg diameters did not differ between consumed eggs and all other eggs (D = 0.061, P = 0.602, Fig. 4B). The same pattern was found when comparing 100 samples randomly drawn from each distribution (D = 0.091, P = 0.813). Moreover, average egg diameters of both groups were statistically similar in size (Phylogenetic ANOVA: F1, 2342 = 0.570, P < 0.723; Fig. 4B).
With the exception of predation events involving the uniquely adapted, bird egg specialist Dasypeltis, snake species in the lowest size classes (i.e., < 2 m in length) mostly consumed narrow bird eggs (< 20 mm; Fig. 5). Larger-bodied species mostly consumed narrow and moderately-sized eggs but also consumed bulkier eggs inaccessible to most other smaller-bodied species.
Our search for reports of snakes consuming bird eggs produced 471 feeding records from 238 individual data sources. From those reports, we produced a global list of oophagous snakes spanning 123 species, 58 genera, and seven families. Our list greatly exceeds prior attempts at cataloguing predatory interactions between snakes and bird eggs but is similarly geographically biased to a few well-sampled regions. For instance, we compiled nearly five times more records of snakes consuming bird eggs than Grundler (2020), 98 records across 50 snake taxa, but 60% of our records were from North America and southern Africa together. Collectively, the snakes on our list consumed the eggs of at least 210 species of birds across a variety of different families and orders. Our examination of traits of identified snake species and bird egg prey revealed that most oophagous snakes are large-bodied terrestrial species and that narrow bird eggs are most frequently, but not disproportionally, consumed. We identified several trends in the data that we hope will form the basis for testable hypotheses and serve as indicators of sampling bias that needs to be addressed.
There are currently 3921 recognized species of snakes (Uetz et al. 2021) distributed across the globe, all of which are predators (Greene 1997, Cundall and Greene 2000). Excluding the 471 species of invertebrate specialist Scolecophidian snakes (i.e., the blind snakes and thread snakes), the vast majority of the remaining 3450 species feed on vertebrate prey. Our list of 123 snake taxa represents a meagre 4% of those species. Bird eggs thus appear to be an uncommon source of prey for snakes overall. However, our list is undeniably an under-representation of the full range of snakes that consume bird eggs. Many congeners and close relatives of several taxa in our list almost certainly also consume bird eggs but have yet to be directly reported as doing so. For example, despite all 16 members of the genus Dasypeltis being known as obligate bird egg specialists (Bates and Little 2013, Bates and Broadley 2018), we only found feeding records for four of these species.
Unsurprisingly, most of the species on our list were represented by only a handful of feeding records. Only ten species had ten or more records, and nearly half of the species were represented by only a single observation. This paucity of feeding records, of which a large proportion represent apparently novel observations, highlights our limited understanding of bird egg predation by snakes. Moreover, additional factors like method-specific biases in feeding data collection also limit the extent of this knowledge. Several studies have highlighted the propensity at which different sampling techniques can affect the quality and quantity of collected dietary information for snakes (Rodrigues-Robles 1998, Glaudas et al. 2017, Maritz and Maritz 2020). As a result, even the diets of species that are relatively “well-known” may be incomplete because the methods used to collect feeding data for those taxa may have been unfavourable towards detecting prey like bird eggs. From this perspective, it is clear that continued reporting of novel feeding records, increased publications of descriptive studies of snake diets, and especially investigations of nest predation will lead to additional identifications of species suitable for inclusion in our list.
Most of the observed predations between snakes and bird eggs took place in the USA. However, at similarly high latitudes east of the Atlantic Ocean, exceedingly few records were reported. Moreover, there were no records at latitudes exceeding 60° N. The paucity of records at high latitudes regions can likely be explained by the limited numbers of snake species that occur in those regions. Snake species richness at high latitudes is relatively low compared to regions closer to the equator and in the southern hemisphere. For example, while there are around 200 species of snakes distributed across the USA there are fewer than 30 species in Canada (Ernst and Ernst 2003). Similarly, in most of northern Europe, there are fewer than 10 species of snakes, and in Russia, there are fewer than 45 species (Uetz et al. 2021). The lack of records from these areas is therefore not surprising given that egg consumption is uncommon in snakes and even in areas with high species richness, there are few records.
External factors unrelated to snake occurrences may also have inhibited records from being published. Several regions with high snake species richness are represented by only a few records of egg consumption (for example, West Africa, North Africa, India, and China). In some of those areas, the financial constraints on publishing may make it difficult to report on observations (see Mekonnen et al. 2021) since it may simply be too expensive to publish, especially for standalone observations like dietary feeding records. Additionally, sampling biases caused by a lack of interest in avian or reptile ecology may also have hindered observations of oophagy being reported.
While detailed dietary records are not available for many species (Grundler 2020), the feeding habits of most snakes are either at least generally known or can be inferred from life-history traits and the diets of their close relatives (Greene 1997, Cundall and Greene 2000). While not without exception, such inferred generalized assertions of snake feeding habits are often supported by detailed dietary studies (Bates and Little 2013, Maritz et al. 2019, Maritz et al. 2021a). Many species of snakes can be ruled out as consumers of bird eggs because they occur in areas where other prey types may be more abundant, easier to forage, or less difficult to consume. Alternatively, these snakes may lack the necessary morphology or physiology to consume eggs. Egg-specialist species like Dasypeltis possess unique adaptations that facilitate egg swallowing such as reduced teeth and vertebral modifications (Gans 1952) that most other snakes do not have. Factors like limitations in gape size, active selection of different prey, differences in encounter rates, and variable habitat use each contribute to the selectivity of different prey types, including bird eggs (de Queiroz and Rodríguez-Robles 2006).
Our results demonstrate that most snakes that consume bird eggs are large-bodied, exceeding 2000 mm in maximum length. Comparatively, the average maximum length of snakes overall is only ~800 mm (Feldman et al. 2016). Snake body size appears to play an important role in the inclusion of bird eggs in snake diets. Longer snakes tend to have larger gapes, and as a result, larger snakes are generally able to consume bulkier and heavier prey than smaller snakes (Arnold 1993, Cundall and Greene 2000). The ovoid shapes and wide cross-sectional diameters of eggs relative to snake head dimensions make them difficult for snakes with narrow gapes to handle and ingest (de Queiroz and Rodríguez-Robles 2006). Some small-bodied species like those in the genera Dasypeltis and Elachistodon overcome these mechanical constraints using specialized morphological features (Bates and Little 2013, Dandge and Tiple 2016) but most other small-bodied snakes are morphologically ill-equipped to ingest this type of prey (Gartner and Greene 2008).
The relationship between snake body size and bird egg prey sizes further illustrates the importance of relative prey bulk in facilitating these interactions. Most snakes, including several large-bodied boas and pythons, consumed relatively narrow eggs compared to their own lengths. This pattern reflects the findings of Gartner and Greene (2008) who quantified the egg-eating performance of Lampropeltis getula and found that adult specimens could only ingest modestly sized eggs relative to the dimensions of their feeding apparatus whereas juveniles could not ingest eggs at all. Those results highlight the body-size mediated mechanical difficulty of bird egg consumption for snakes and support the general predator-size, prey-size pattern found here. However, this pattern is not without exception given that several snakes consume bulky chicken, duck, and goose eggs.
Apart from body size and gape size limitations, specific predispositions towards hunting particular prey also preclude several species of snakes from predating bird eggs. In snakes, the habit of eating the eggs of an animal tends to arise from first eating the corresponding laying animal (de Queiroz and Rodríguez-Robles 2006, Maritz et al. 2021c). This is thought to be because the eggs of an animal share chemical cues with the parent animal, and so 1) this allows snakes to recognize the eggs as suitable food, and 2) leads to greater encounter rates of those organisms (de Queiroz and Rodríguez-Robles 2006). As a result, because relatively few species of snakes consume birds (Greene 1997, Cundall and Greene 2000), few species consume the eggs of birds because they do not associate them as appropriate prey.
Snakes may also actively exclude bird eggs from their diet in favour of other prey. Relative to their size, bird eggs are filled with calories, lipids, proteins, and water (Sotherland and Rahn 1987) but because of their size and associated high handling costs offer lower energetic payoffs to most other vertebrate prey (Greene et al. 2013). Snakes that prey on bird eggs can compensate for this by eating multiple eggs in a single meal, a trend that our data suggests occurs often. However, most species of birds lay small clutches with few eggs (Baicich and Harrison 2005, Tarboton 2011). Moreover, bird eggs are sedentary and nests are often difficult to locate (Nalwanga et al. 2004). For many species of snakes, the energetic costs of searching for nests with eggs likely outweigh the costs of foraging other, more easily detectable and energetically profitable prey. As a result, it is likely optimal for most snakes to exclude bird eggs in favour of other prey. In particular, large snakes should theoretically prefer singular, heavy prey items that provide a surplus of energy whereas smaller-bodied snakes probably prefer less bulky prey that are easier to consume (Shine 1991a).
Differences in foraging mode (i.e., active foraging versus ambush foraging) and lifestyle habits between snakes also greatly affect the chances of species encountering sedentary prey like bird eggs (Greene 1997, Alencar et al. 2013). Sit-and-wait foraging snakes probably only rarely encounter nesting birds and even less so bird eggs. Similarly, aquatic and fossorial species will encounter bird eggs considerably less often than arboreal and terrestrial species. Surprisingly, the majority of the species in our list were terrestrial rather than arboreal or semi-arboreal. However, we suspect that this is likely an artefact of sampling bias rather than a reflection of true biological patterns as terrestrial snakes are easier to detect than arboreal species (Pizzatto et al. 2007). Additionally, most occurrences of egg predation took place in habitats at low elevations (< 500 m above sea level) which could also be indicative of biased sampling efforts since high altitudes are generally difficult to access.
Identifying the snake predators of bird eggs is a key first step toward understanding the extent of their roles in nest predation and the potential implications thereof (Weatherhead and Blouin-Demers 2004, Lahti 2009; Menezes and Marini 2017). By knowing which snakes occur in a given area and which of those species eat bird eggs, researchers can consider species-specific hypotheses informed by existing knowledge of the demographics, ecologies, and natural histories of those particular species (for example Barends and Maritz 2021). Ultimately, this will lead to investigations that further our understanding of the relative importance of different snakes towards avian breeding success and more broadly, their impacts on ecosystem functioning (Reidy and Thompson 2012, DeGregorio et al. 2016a). Importantly, these investigations can also inform conservation strategies that seek to manage or protect endangered or vulnerable species of birds (Carter et al. 2007, Thompson and Ribic 2012).
Our primary objective of this review was to compile a comprehensive list of snake species unambiguously categorized as predators of bird eggs. We hope that this list can act as a baseline for further research seeking to understand patterns of nest predation by snakes and their impacts on avian ecology. By searching through the literature, citizen science reports, and social media, we provide a summary of accounts of bird egg predation by snakes that can act as a foundation for a consolidated database for further research.
We thank the various authors who have published observations of snakes predating bird eggs. We further thank Harry Greene, Steven Spawls, Sahas Barve, Praveen Jayadevan, Yatin Kalki, and especially Gustavo Adolfo Londoño Guerrero for pointing us towards additional feeding records. This work was supported by the National Research Foundation (UIDs: 118090, 123281, and 139202).
Supplementary electronic datasets are available on Figshare https://doi.org/10.6084/m9.figshare.19508938.
Aldrich, J., and C. Endicott. 1984. Black rat snake predation on giant Canada Goose eggs. Wildlife Society Bulletin 12:263-264.
Alencar, L. R., M. P. Gaiarsa, and M. Martins. 2013. The evolution of diet and microhabitat use in pseudoboine snakes. South American Journal of Herpetology 8:60-66. https://doi.org/10.2994/SAJH-D-13-00005.1
Alexander, G. J. 2012. Predation/Diet. Python natalensis. African Herp News 56:25-25.
Allison, S., and L. Smith. 2018. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/505098069990974 (Accessed 30 August 2021).
Al-Safadi, M. M. 2004. On the breeding biology of the Syrian Woodpecker, Dendrocopos syriacus, in the Gaza Strip. Zoology in the Middle East 32:7-12. https://doi.org/10.1080/09397140.2004.10638038
Amr, Z. S., and A. M. Disi. 1998. Diet of some snakes from Jordan. Amphibia-Reptilia 19:436-439. https://doi.org/10.1163/156853898X00106
Andrews, R. 1952. A study of waterfowl nesting on a Lake Erie marsh. M. S. thesis, Ohio State University, Columbus, Ohio, USA.
Angulo, F., and G. Chavez. 2017. First report of predation on Speckled Chachalaca (Ortalis guttata) eggs by puffing snake (Phrynonax polylepis) in central Peru. Bulletin of the Union of Ornithologists of Peru 12:27-33.
Applegate, R. D. 1995. Sistrurus catenatus catenatus. Food habits. Herpetological Review 26:206-206.
Arnold, S. J. 1993. Foraging theory and prey-size-predator-size relations in snakes. Pages 87-115 in R. A. Seigel and J. T. Collins, editors. Snakes: Ecology and Behaviour. McGraw-Hill, New York City, New York, USA.
Auer, S. K., R. D. Bassar, J. J. Fontaine, and T. E. Martin. 2007. Breeding biology of passerines in a subtropical montane forest in northwestern Argentina. Condor 109:321-333. https://doi.org/10.1093/condor/109.2.321
Baicich, P. J., and C. J. O. Harrison. 2005. Nests, eggs, and nestlings of North American birds. Second Edition. Princeton University Press, New Jersey, New York, USA.
Balakrishnan, P. 2010. Reproductive biology of the square-tailed Black Bulbul Hypsipetes ganeesa in the Western Ghats, India. Indian Birds 5:134-138.
Barbour, T., and A. Loveridge. 1928. A comparative study of the herpetological faunae of the Uluguru and Usambara Mountains, Tanganyika Territory with descriptions of new species. Memoires of the Museum of Comparative Zoology 50:85-265. https://doi.org/10.5962/bhl.title.49344
Barends, J. M., and B. Maritz. 2021. Specialized morphology, not relatively large head size, facilitates competition between a small-bodied specialist and large-bodied generalist competitors. Journal of Zoology 315:213-224. https://doi.org/10.1111/jzo.12914
Barends, J. M., and B. Maritz. 2022. Dietary specialization and habitat shifts in a clade of Afro-Asian colubrid snakes (Colubridae: Colubrinae). Ichthyology and Herpetology 110(2). In press.
Bars-Closel, M., T. Kohlsdorf, D. S. Moen, and J. J. Wiens. 2017. Diversification rates are more strongly related to microhabitat than climate in squamate reptiles (lizards and snakes). Evolution 71:2243-2261. https://doi.org/10.1111/evo.13305
Bates, M. F., and D. G. Broadley. 2018. A revision of the egg-eating snakes of the genus Dasypeltis Wagler (Squamata: Colubridae: Colubrinae) in north-eastern Africa and south-western Arabia, with descriptions of three new species. Indago 34:1-95.
Bates, M. F., and I. T. Little. 2013. Predation on the eggs of ground-nesting birds by Dasypeltis scabra (Linnaeus, 1758) in the moist highland grasslands of South Africa. African Journal of Herpetology 62:125-134. https://doi.org/10.1080/21564574.2013.786760
Beebe, W. 1946. Field notes on the snakes of Kartabo, British Guiana, and Caripito, Venezuela. Zoologica 31:11-53. https://doi.org/10.5962/p.203521
Bent, A. C., and O. L. Austin Jr. 1968. Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies. Dover Publications, New York City, New York, USA. https://doi.org/10.5479/si.03629236.237.1
Bernarde, P. S., and A. S. Abe. 2006. A snake community at Espigão do Oeste, Rondônia, southwestern Amazon, Brazil. South American Journal of Herpetology 1:102-113. https://doi.org/10.2994/1808-9798(2006)1[102:ASCAED]2.0.CO;2
Best, L. B. 1974. Blue racers prey on Field Sparrow nests. Auk 91:168-169. https://doi.org/10.2307/4084677
Best, L. B. 1977. Bull snake preys on Rough-winged Swallow nest. Condor 79:509-510. https://doi.org/10.2307/1367740
Blomberg, S. P., T. Garland Jr, and A. R. Ives. 2003. Testing for phylogenetic signal in comparative data: behavioral traits are more labile. Evolution 57:717-745. https://doi.org/10.1111/j.0014-3820.2003.tb00285.x
Brandt, J. H. 1962. Nests and eggs of the birds of the Truk Islands. Condor 64:416-437. https://doi.org/10.2307/1365549
Britto, Y. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/905268206640623 (Accessed 30 August 2021).
Broadley, D. G. 1959. The herpetology of southern Rhodesia. Part 1: Snakes. Bulletin of the Museum of Comparative Zoology 120:1-100.
Brown, C., and L. Smith. 2017. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/256623638171753 (Accessed 30 August 2021).
Brown, E. E. 1979a. Some snake food records from the Carolinas. Brimleyana 1:113-124.
Brown, E. E. 1979b. Stray food records from New York and Michigan snakes. American Midland Naturalist 102:200-203. https://doi.org/10.2307/2425088
Brown, W., and J. C. Mitchell. 2005. Elaphe alleghaniensis (eastern ratsnake). Foraging behavior. Herpetological Review 36:193-194.
Bruderer, B. 1991. Common egg-eater Dasypeltis scabra killed at Fiscal Shrike Lanius collaris nest. Ostrich Journal of African Ornithology 62:76-77.
Brush, S. W., and G. W. Ferguson. 1986. Predation on Lark Sparrow eggs by a massasauga rattlesnake. Southwestern Naturalist 31:260-261. https://doi.org/10.2307/3670575
Burnside, R. J., A. L. Brighten, N. J. Collar, V. Soldatov, M. Koshkin, P. M. Dolman, and A. Ten. 2020. Breeding productivity, nest-site selection and conservation needs of the endemic Turkestan Ground-jay Podoces panderi. Journal of Ornithology 161:1175-1183. https://doi.org/10.1007/s10336-020-01790-9
Calf, K. M. 2004. Mole snake Pseudaspis cana predation of African Black Oystercatcher Haematopus moquini eggs. Wader Study Group Bulletin 104:103-104.
Callhoun, J. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/886264498540994 (Accessed 30 August 2021).
Campbell, T. C., and L. Smith. 2018. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/419264235241025 (Accessed 30 August 2021).
Cansdale, G. S. 1961. West African snakes. Addison-Wesley Longman Limited, Boston, Massachusetts USA.
Capula, M., and L. Luiselli. 2002. Feeding strategies of Elaphe longissima from contrasting Mediterranean habitats in central Italy. Italian Journal of Zoology 69:153-156. https://doi.org/10.1080/11250000209356453
Carter Jr, G. V. 1970. Black ratsnake predation upon nesting Barn and Cliff Swallow. Bulletin of the Oklahoma Ornithological Society 3:17-20.
Carter, G. M., M.L. Legare, D.R. Breininger, and D. M. Oddy. 2007. Nocturnal nest predation: a potential obstacle to recovery of a Florida Scrub-jay population. Journal of Field Ornithology 78:390-394. https://doi.org/10.1111/j.1557-9263.2007.00127.x
Cattaneo, A. 1979. Osservazioni sulla nutrizione di Elaphe quatuorlineata (Lac.) a Castelporziano (Roma). Atti della Società Italiana di scienze naturali e del Museo civico di storia naturale di Milano 120:203-218.
Cattaneo, A., and M. Grano. 2013. The Aegean populations of Elaphe quatuorlineata (Lacépède, 1789): a morpho-ecological examination. Pages 269-288 in K. D. Schulz, editor. Old World Ratsnakes—a Collection of Papers. Bushmaster Publications, Berg SG, Switzerland.
Cavitt, J. F. 2000. Tallgrass prairie snake assemblage. Food habits. Herpetological Review 31:47-48.
Cerón-Cardona, J., and G. A. Londoño. 2017. Nesting biology of the Sooty Antibird (Hafferia fortis) in southeastern Peru. Wilson Journal of Ornithology 129:576-585. https://doi.org/10.1676/16-020.1
Chaitae, A. 2011. Demography of the monocled cobra (Naja kaouthia) in the central region of Thailand. M. S. thesis, University of Louisville, Louisville, Kentucky, USA. https://doi.org/10.18297/etd/228
Chen, P., T. Chen, B. Liu, M. Zhang, C. Lu, and Y. Chen. 2020. Snakes are the principal nest predators of the threatened Reed Parrotbill in a coastal wetlands of eastern China. Global Ecology and Conservation 23:e01055. https://doi.org/10.1016/j.gecco.2020.e01055
Chen, W. J., P. F. Lee, and R. S. Lin. 2015. Identifying predators of Passerine shrub and ground nests in a lowland forest of Taiwan. Taiwan Journal of Biodiversity 17:101-120.
Cheng, Y. R., D. R. Rubenstein, and S. F. Shen. 2019. Nest predation predicts infanticide in a cooperatively breeding bird. Biology Letters 15:20190314. https://doi.org/10.1098/rsbl.2019.0314
Cisneros-Heredia, D.F. 2005. Pseuestes poecilonotus and Pseuestes shropshirei (puffing snakes). Diet. 2005. Herpetological Review 36:326-327.
Cochran, C.A. 2013. Spilotes pullatus (tiger ratsnake). Diet. Herpetological Review 44:697-697.
Colahan, B. D. 1982. The biology of the Orangebreasted Waxbill. Ostrich Journal of African Ornithology 53:1-30. https://doi.org/10.1080/00306525.1982.9634722
Compton, L. V. 1933. King snake eating eggs of California Quail. Condor 35:71-72.
Conant, R. 1938. The reptiles of Ohio. American Midland Naturalist 20:1-200. https://doi.org/10.2307/2485190
Conry, P. J. 1988. High nest predation by brown tree snakes on Guam. Condor 90:478-482. https://doi.org/10.2307/1368576
Corkill, N. L. 1935. Notes on Sudan snakes: a guide to the species represented in the collection in the Natural History Museum, Khartoum. Sudan Government Natural History Museum, Khartoum, Sudan.
Covas, R. V., M. A. du Plessis, and C. Doutrelant. 2008. Helpers in colonial cooperatively breeding Sociable Weavers Philetairus socius contribute to buffer the effects of adverse breeding conditions. Behavioural Ecology and Sociobiology 63:103-112. https://doi.org/10.1007/s00265-008-0640-2
Cundall, D., and H. W. Greene. 2000. Feeding in snakes. Pages 293-333 in K. Schwenk, editor. Feeding: form, function, and evolution in tetrapod vertebrates. Academic Press, San Diego, California, USA. https://doi.org/10.1016/B978-012632590-4/50010-1
Cunha, O. R. D., and F. P. D. Nascimento. 1983. Ofídios da Amazônia XX-as espécies de Atractus Wagler, 1828, na Amazônia oriental e Maranhão (Ophidia, Colubridae). Boletim do Museu Paraense Emílio Goeldi. Nova série Zoologia 123:1-38.
Cutler, T. L., and D. E. Swann. 1999. Using remote photography in wildlife ecology: a review. Wildlife Society Bulletin 27:571-581.
Cyriac, V. P., and U. Kodandaramaiah. 2018. Digging their own macroevolutionary grave: fossoriality as an evolutionary dead end in snakes. Journal of Evolutionary Biology 31:587-598. https://doi.org/10.1111/jeb.13248
da Costa-Prudente, A. L., A. Costa-Menks, F. M. da Silva, and G. F. Maschio. 2014. Diet and reproduction of the western indigo snake Drymarchon corais (Serpentes: Colubridae) from the Brazilian Amazon. Herpetology Notes 7:99-108.
Dandge, P. H. 2008. Food and feeding habits of Elachistodon westermanni Reinhardt, 1863. Hamadryad 32:86-88.
Dandge, P. H., and A. D. Tiple. 2016. Notes on natural history, new distribution records and threats of Indian Egg Eater Snake Elachistodon westermanni Reinhardt, 1863 (Serpentes: Colubridae): Implications for conservation. Russian Journal of Herpetology 23:55-62.
de Queiroz, A., and J. A. Rodríguez-Robles. 2006. Historical contingency and animal diets: the origins of egg eating in snakes. American Naturalist 167:684-694. https://doi.org/10.1086/503118
De Waal, S. W. P. 1977. The Squamata (Reptilia) of the Orange Free State, South Africa. Ph.D thesis, University of Natal, Durban, Kwa-Zulu Natal, South Africa.
DeGregorio, B. A., S. J. Chiavacci, P. J. Weatherhead, J. D. Willson, T. J Benson, and J. H. Sperry. 2014. Snake predation on North American bird nests: culprits, patterns and future directions. Journal of Avian Biology 45:325-333. https://doi.org/10.1111/jav.00364
DeGregorio, B. A., S. J. Chiavacci, T. J Benson, J. H Sperry, and P. J. Weatherhead. 2016a. Nest predators of North American birds: continental patterns and implications. BioScience 66:655-665. https://doi.org/10.1093/biosci/biw071
Degregorio, B. A., P. J. Weatherhead, and J. H. Sperry. 2016b. Ecology and predation behavior of corn snakes (Pantherophis guttatus) on avian nests. Herpetological Conservation and Biology 11:150-159.
Delaney, D., L. Pater, L. Carlile, D. Stevenson, and A. Walde. 2008. Red-cockaded Woodpecker (Picoides borealis) response to nest depredation by an eastern rat snake (Elaphe alleghaniensis). Southeastern Naturalist 7:753-759. https://doi.org/10.1656/1528-7092-7.4.753
Diller, L. V., and R. L. Wallace. 1996. Comparative ecology of two snake species (Crotalus viridis and Pituophis melanoleucus) in southwestern Idaho. Herpetologica 52:343-360.
Dixon, J.R., and P. Soini. 1986. The reptiles of the upper Amazon basin, Iquitos Region, Peru. Milwaukee Public Museum, Milwaukee, Wisconsin, USA.
dos Santos-Costa, M. C., G. F. Maschio, and A. L. da Costa Prudente. 2015. Natural history of snakes from Floresta Nacional de Caxiuanã, eastern Amazonia, Brazil. Herpetology Notes 8:69-98.
Dove, C. J., R. N. Reed, and R. W. Snow. 2012. Consumption of bird eggs by invasive Burmese pythons in Florida. Reptiles and Amphibians 19:64-66. https://doi.org/10.17161/randa.v19i1.13848
Dusi, J. L., and R. T. Dusi. 1968. Ecological factors contributing to nesting failure in a heron colony. Wilson Bulletin 80:458-466.
Dyer, B. M. 1996. Predation by snakes on seabirds at three South African islands. South African Journal of Marine Science 17:309-313. https://doi.org/10.2989/025776196784158374
Ernst, C. H., and E. M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Books, Washington D.C., Washington, USA
Fearn, S., B. Robinson, J. Sambono, and R. Shine. 2001. Pythons in the pergola: the ecology of 'nuisance' carpet pythons (Morelia spilota) from suburban habitats in south-eastern Queensland. Wildlife Research 28:573-579. https://doi.org/10.1071/WR00106
Feldman, A., and S. Meiri. 2014. Australian snakes do not follow Bergmann’s rule. Evolutionary Biology 41:327-335. https://doi.org/10.1007/s11692-014-9271-x
Feldman, A., N. Sabath, R. A. Pyron, I. Mayrose, and S. Meiri. 2016. Body sizes and diversification rates of lizards, snakes, amphisbaenians and the tuatara. Global Ecology and Biogeography 25:187-197. https://doi.org/10.1111/geb.12398
Fick, S. E., and R. J. Hijmans. 2017. WorldClim 2: new 1km spatial resolution climate surfaces for global land areas. International Journal of Climatology 37:4302-4315. https://doi.org/10.1002/joc.5086
Filippi, E., L. Rugiero, M. Capula, D. Capizzi, and L. Luiselli. 2005. Comparative food habits and body size of five populations of Elaphe quatuorlineata: the effects of habitat variation, and the consequences of intersexual body size dimorphism on diet divergence. Copeia 2005:517-525. https://doi.org/10.1643/CH-04-350R1
Fiorillo, B. F. 2019. Predation on eggs of the Gray Tinamou (Tinamus tao, Tinamiformes: Tinamidae) by the rainbow boa (Epicrates cenchria, Serpentes: Boidae). Herpetology Notes 12:79-81.
Fitch, H. S. 1963a. Natural history of the black rat snake (Elaphe o. obsoleta) in Kansas. Copeia 1963:649-658. https://doi.org/10.2307/1440967
Fitch, H. S. 1963b. Natural history of the racer Coluber constrictor. University of Kansas Publications of the Museum of Natural History 15:351-468. https://www.gutenberg.org/files/42676/42676-h/42676-h.htm
Fitch, H. S. 1978. A field study of the prairie kingsnake (Lampropeltis calligaster). Transactions of the Kansas Academy of Science 81:353-363. https://doi.org/10.2307/3627386
Fitch, H. S. 1998. A Kansas snake community: composition and changes over 50 years. Krieger Publishing Company, Malabar, Florida, USA
Folsom, L. 2018. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/393372987830150 (Accessed 30 August 2021).
Fraga, R. M., H. Casañas, and G. Pugnali. 1998. Natural history and conservation of the endangered Saffron-cowled Blackbird Xanthopsar flavus in Argentina. Bird Conservation International 1998:255-267. https://doi.org/10.1017/S095927090000191X
França, F. G., D. O. Mesquita, C. C. Nogueira, and A. F. Araújo. 2008. Phylogeny and ecology determine morphological structure in a snake assemblage in the central Brazilian Cerrado. Copeia 2008:23-38. https://doi.org/10.1643/CH-05-034
Fry, C. H. 1984. The Bee-eaters. A and C Black, London, UK.
Fulton, G. R. 2018. Avian nest predation in Australian temperate forest and woodland: a review. Pacific Conservation Biology 24:122-133. https://doi.org/10.1071/PC17035
Gabrielson, I. N. 1922. Factors contributing to the destruction of bird's nests and eggs. Bird Lore 24:136-139.
Gaiarsa, M. P., L. R. de Alencar, and M. Martins. 2013. Natural history of Pseudoboine snakes. Papéis Avulsos de Zoologia 53:261-283. https://doi.org/10.1590/S0031-10492013001900001
Gans, C. 1952. The functional morphology of the egg-eating adaptations in the snake genus Dasypeltis. Zoologica 37:209-244. https://doi.org/10.5962/p.203469
Garnett, S. T., D. E. Duursma, G. Ehmke, P. J. Guay, A. Stewart, J. K. Szabo, M. A. Weston, S. Bennett, G. M. Crowley, D. Drynan, G. Dutson, K. Fitzherbert, and Franklin. 2015. Biological, ecological, conservation and legal information for all species and subspecies of Australian bird. Scientific Data 2:1-6. https://doi.org/10.1038/sdata.2015.61
Gartner, G. E. A., and H. W. Greene. 2008. Adaptation in the African egg-eating snake: a comparative approach to a classic study in evolutionary functional morphology. Journal of Zoology 275: 68-374. https://doi.org/10.1111/j.1469-7998.2008.00448.x
Gascon, C., T. M. Brooks, T. Contreras-MacBeath, N. Heard, W. Konstant, J. Lamoreux, F. Launay, M. Maunder, R. A. Mittermeier, S. Molur, R. K. Al Mubarak, M. J. Parr, A. G. J. Rhodin, A. B. Rylands, P. Soorae, J. G. Sanderson, and J. Vie. 2015. The importance and benefits of species. Current Biology 25:431-438. https://doi.org/10.1016/j.cub.2015.03.041
Gatica-Colima, A. 2015. Coluber (= Masticophis) bilineatus (Sonoran whipsnake). Diet. Herpetological Review 46: 00-101.
Glaudas, X., T. C. Kearney, and G. J. Alexander. 2017. Museum specimens bias measures of snake diet: a case study using the ambush-foraging puff adder (Bitis arietans). Herpetologica 73:121-128. https://doi.org/10.1655/HERPETOLOGICA-D-16-00055
Godínez, E., M. Gómez, J. A. Puentes, and S. Vargas. 1987. Características reproductivas de Columba leucocephala en la Península de Guanahacabibes, Cuba. Poeyana 340:1-8.
Gosse, P. H. 1851. A naturalist's sojourn in Jamaica. Cambridge University Press, London, UK https://doi.org/10.1017/CBO9781139628693
Greene, H. W. 1989. Ecological, evolutionary, and conservation implications of feeding biology in Old World cat snakes, genus Boiga (Colubridae). Proceedings of the California Academy of Sciences 46:193-207.
Greene, H. W. 1997. Snakes: the evolution of mystery in nature. University of California Press, Los Angeles, California, USA. https://doi.org/10.1525/9780520935433
Greene, S., S. McConnachie, S. Secor, and M. Perrin. 2013. The effects of body temperature and mass on the postprandial metabolic responses of the African egg-eating snakes Dasypeltis scabra and Dasypeltis inornata. Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology 165:97-105. https://doi.org/10.1016/j.cbpa.2013.02.023
Greuel, J. 2020. Foraging ecology of Dispholidus typus and Naja nivea. M. S. thesis, University of the Western Cape, Cape Town, Western Cape, South Africa.
Grundler, M. C. 2020. SquamataBase: a natural history database and R package for comparative biology of snake feeding habits. Biodiversity Data Journal 8:e49943. https://doi.org/10.3897/BDJ.8.e49943
Guthrie, J. E. 1932. Snakes versus birds; birds versus snakes. Wilson Bulletin 44:88-113.
Haagner, G. V. 1993. Life history notes: Naja annulifera diet. Journal of the Herpetological Association of Africa 42:39-40.
Hackney, A. D., J. C. Mitchell, and P. P. Denmon. 2014. Snake predation on American Oystercatcher eggs on Fisherman Island, Virgina. Banisteria 43:101-103.
Hansen, J. L., and L. H. Fredrickson. 1990. Black rat snake predation on box nesting Wood Ducks. Pages 251-254 in L.H. Fredrickson, G. V. Burger, S. P. Havera, D. A. Graber, R. E. Kirby, and T. S. Taylor, editors. The 1988 North American Wood Duck symposium. The Symposium, St. Louis, Missouri, USA.
Harrington, S. M., J. M. De Haan, L. Shapiro, and S. Ruane. 2018. Habits and characteristics of arboreal snakes worldwide: arboreality constrains body size but does not affect lineage diversification. Biological Journal of the Linnean Society 125:61-71. https://doi.org/10.1093/biolinnean/bly097
Harrison, C. J. O., and P. Castell. 2002. Bird nests, eggs and nestlings of Britain and Europe with North Africa and the Middle East. Second revised edition. HarperCollins, London, UK.
Hasegawa, M., and H. Moriguchi. 1989. Geographic variation in food habits, body size and life history traits of the snakes on the Izu Islands. Current Herpetology in East Asia 1989:414-432.
Hathcock, C. D. 2013. Pituophis catenifer (gophersnake). Diet. Herpetological Review 44:526-526.
Henderson, R. W. 1982. Trophic relationships and foraging strategies of some New World tree snakes (Leptophis, Oxybelis, Uromacer). Amphibia-Reptilia 3:71-80. https://doi.org/10.1163/156853882X00185
Hewitt, J., and J. H. Power. 1913. A list of South African Lacertilia, Ophidia, and Batrachia in the McGregor Museum, Kimberley; with field-notes on various species. Transactions of the Royal Society of South Africa 3:147-176. https://doi.org/10.1080/00359191309519688
Heyns, G., and L. Smith. 2018. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/524971531336961 (Accessed Accessed 30 August 2021).
Hockey, P. A., W. R. J. Dean, P. G. Ryan, S. Maree, and B. M. Brickman. 2005. Roberts' birds of southern Africa. Trustees of the John Voelcker Bird Book Fund, Cape Town, Western Cape, South Africa.
Holingsworth, B. 2016. Lampropeltis californiae. Diet/Oophagy. Herpetological Review 47:684-684.
Ibáñez-Álamo, J. D., R. D. Magrath, J. C. Oteyza, A. D. Chalfoun, T. M. Haff, K. A. Schmidt, R. L. Thomson, and T. E. Martin. 2015. Nest predation research: recent findings and future perspectives. Journal of Ornithology 156:247-262. https://doi.org/10.1007/s10336-015-1207-4
Imler, R. H. 1945. Bullsnakes and their control on a Nebraska wildlife refuge. Journal of Wildlife Management 9:265-273. https://doi.org/10.2307/3796368
Iverson, J.B., and T. S. Akre. 2001. Pituophis melanoleucus sayi (bullsnake). Diet. Herpetological Review 32:109-110.
Jacobsen, N. H. G. 1989. A herpetological survey of the Transvaal. Ph.D. thesis, University of Natal, Durban, Kwa-Zulu Natal, South Africa.
Jadin, R. C., and S. A. Orlofske. 2020. Pantherophis vulpinus (eastern foxsnake). Diet. Herpetological Review 51:152-152.
Jamie, G. A., C. Moya, and L. Hamusikili. 2016. Incubation and nest-defence behavior of Streaky-breasted Flufftail Sarothrura boehmi in Zambia. Bulletin of the African Bird Club 23:82-85. https://doi.org/10.5962/p.310077
Jetz, W., G. H. Thomas, J. B. Joy, K. Hartmann, and A. O. Mooers. 2012. The global diversity of birds in space and time. Nature 491:444-448. https://doi.org/10.1038/nature11631
Jiang, Y. L., W. Gao, F. M. Lei, H. T. Wang, D. M. Wan, and J. Zhao. 2008. Nesting biology and population dynamics of Jankowski's Bunting Emberiza jankowskii in Western Jilin, China. Bird Conservation International 18:153-163. https://doi.org/10.1017/S0959270908000154
Jokay, J. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/855223754978402 (Accessed 30 August 2021).
Khamcha, D., and G. A. Gale. 2020. Predation behaviour of the bridle snake (Lycodon cf. davisonii) on Asian tropical evergreen forest bird nests. Raffles Bulletin of Zoology 68:803-809.
Khamcha, D., L. A. Powell, and G. A. Gale. 2018. Effects of roadside edge on nest predators and nest survival of Asian tropical forest birds. Global Ecology and Conservation 16:e00450. https://doi.org/10.1016/j.gecco.2018.e00450
Klauber, L. M. 1931. A statistical survey of the snakes of the southern border of California. Zoological Society of San Diego, San Diego, California, USA. https://doi.org/10.5962/bhl.title.130502
Klimstra, W. D. 1959. Food habits of the yellow-bellied king snake in southern Illinois. Herpetologica 15:1-5.
Klug, P., L. Wolfenbarger, and J. McCarty. 2010. Snakes are important nest predators of dickcissels in an agricultural landscape. Wilson Journal of Ornithology 122:799-803. https://doi.org/10.1676/09-203.1
Koen, T. 2021. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/3678915028810990 (Accessed 30 August 2021).
Kok, O. B., M. M. Roos, and Z. N. Roos. 1977. Broeisukses van Rooivinke in die Willem Pretorius-wildtuin. Acta Academiae Aboensis 10:5-11.
Krüger, O. 2004. Breeding biology of the Cape Bulbul Pycnonotus capensis: a 40-year comparison. Ostrich Journal of African Ornithology 75:211-216. https://doi.org/10.2989/00306520409485447
Lahti, D. C. 2009. Why we have been unable to generalize about bird nest predation. Animal Conservation 12:279-281. https://doi.org/10.1111/j.1469-1795.2009.00286.x
Landoll, D. V., and M. S. Husak. 2011. Depredation of a nest of the Eastern Meadowlark (Sturnella magna) by a speckled kingsnake (Lampropeltis getula holbrooki). Southwestern Naturalist 56:433-435. https://doi.org/10.1894/N10-KF-17.1
Langford, G., and J. Janovy. 2011. Heterodon nasicus (western hog-nosed snake). Diet and arboreal foraging behavior. Herpetological Review 42:291-291.
Langlois, T. H. 1964. Amphibians and reptiles of the Erie islands. Ohio Journal of Science 64:11-25.
Lavers, J. L., C. Wilcox, and C. J. Donlan. 2010. Bird demographic responses to predator removal programs. Biological Invasions 12:3839-3859. https://doi.org/10.1007/s10530-010-9776-x
Lawing, A. M., J. J. Head, and P. D. Polly. 2012. The ecology of morphology: the ecometrics of locomotion and macroenvironment in North American snakes. Pages 117-146 in J. Louys, editor. Paleontology in Ecology and Conservation. Springer-Verlag, Berlin, Berlin, Germany. https://doi.org/10.1007/978-3-642-25038-5_7
Layloo, I., C. Smith, and B. Maritz. 2017. Diet and feeding in the cape cobra, Naja nivea. African Journal of Herpetology 66:147-153. https://doi.org/10.1080/21564574.2017.1388297
Lennon, C. P. 2013. Dietary ecology of an actively-foraging snake species, Coluber constrictor foxii. M. S. thesis, Eastern Illinois University, Charleston, Illinois, USA.
Leopold, F. 1966. Experiences with home-grown Wood Ducks. Wood duck management and research: a symposium. Wildlife Management Institute, Washington D.C., Washington, USA.
Li, J., L. Lv, Y. Wang, B. Xi, and Z. Zhang. 2012. Breeding biology of two sympatric Aegithalos Tits with helpers at the nest. Journal of Ornithology 153:273-283. https://doi.org/10.1007/s10336-011-0740-z
Linton, E. H. 1930. Some notes concerning two of the cuckoos: Lamprococcyx plagosus Gould and Cacomantis flabelliformis Sharpe. Emu-Austral Ornithology 29:304-307. https://doi.org/10.1071/MU929304
Little, R. M., and T. M. Crowe. 1993. The breeding biology of the Greywing Francolin Francolinus africanus and its implications for hunting and management. South African Journal of Zoology 28:6-12. https://doi.org/10.1080/02541858.1993.11448291
Lloyd, P. 2004. Variation in nest predation among arid-zone birds. Ostrich Journal of African Ornithology 75:228-235. https://doi.org/10.2989/00306520409485449
Lloyd, P., R. M. Little, and T. M. Crowe. 2001. The breeding biology of the Namaqua Sandgrouse, Pterocles namaqua. Ostrich Journal of African Ornithology 72:169-178. https://doi.org/10.2989/00306520109485313
Lloyd, P., W. A. Taylor, M. A. du Plessis, and T. E. Martin. 2009. Females increase reproductive investment in response to helper-mediated improvements in allo-feeding, nest survival, nestling provisioning and post-fledgling survival in the Karoo Scrub-robin Cercotrichas coryphaeus. Journal of Avian Biology 40:400-411 https://doi.org/10.1111/j.1600-048X.2008.04642.x
Lockyer, Z. B., P. S. Coates, M. L. Casazza, S. Espinosa, and D. J. Delehanty. 2013. Greater Sage-grouse nest predators in the Virginia Mountains of northwestern Nevada. Journal of Fish and Wildlife Management 4:242-255. https://doi.org/10.3996/122012-JFWM-110R1
Lopez, M. S., A. R. Giraudo, and V. Arzamendia. 2003. Leptophis ahaetulla marginatus (southern green parrot snake). Diet. Herpetological Review 34:68-69.
Loveridge, A. 1936. Scientific results of an expedition to rain forest regions in eastern Africa. Bulletin of the Museum of Comparative Zoology at Harvard College 79:3-19.
Loveridge, A. 1945. A guide to the snakes of the Nairobi district. Journal of the East Africa Natural History Society 18:97-115.
Loveridge, A. 1953. Reptiles from Nyasaland and Tete. Bulletin of the Museum of Comparative Zoology 110:143-322.
Lowney, A. M., and R. L. Thomson. 2021. Ecological engineering across a temporal gradient: Sociable Weaver colonies create year‐round animal biodiversity hotspots. Journal of Animal Ecology 90:2362-2376. https://doi.org/10.1111/1365-2656.13544
Ma, Q., L. L. Severinghaus, W. H. Deng, and Z. Zhang. 2016. Breeding biology of a little-known raptor in central China: The Chinese Sparrowhawk (Accipiter soloensis). Journal of Raptor Research 50:176-184. https://doi.org/10.3356/rapt-50-02-176-184.1
Macdonald, I. A. W., and W. R. J. Dean. 1978. A record of egg predation by the East African egg-eater Dasypeltis medici (Squamata: Colubridae). African Zoology 13:163-163. https://doi.org/10.1080/00445096.1978.11447616
Maclean, G. L. 1973. The Sociable Weaver, Part 4: Predators, parasites and symbionts. Ostrich Journal of African Ornithology 44:241-253. https://doi.org/10.1080/00306525.1973.9639161
Mancina, C.A., and A. Llanes Sosa. 1997. Indicios de depredación de huevos de Hirundo fulva (Passeriformes: Hirundinidae) por Epicrates angulifer (Serpentes: Boidae). El Pitirre 10:95-96.
Marion, W. R., and R. J. Fleetwood. 1978. Nesting ecology of the Plain Chachalaca in south Texas. Wilson Bulletin 90:386-395.
Maritz, A., and T. J. Ping. 2020. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/3430188537016975 (Accessed 30 August 2021).
Maritz, B., and G. J. Alexander. 2014. Namaqua dwarf adders are generalist predators. African Journal of Herpetology 63:79-86. https://doi.org/10.1080/21564574.2013.836137
Maritz, B., G. J. Alexander and R. A Maritz. 2019. The underappreciated extent of cannibalism and ophiophagy in African cobras. Ecology 100:e02522. https://doi.org/10.1002/ecy.2522
Maritz, B, A. Rawoot, and R van Huyssteen. 2021a. Testing assertions of dietary specialisation: a case study of the diet of Aparallactus capensis. African Journal of Herpetology 70:61-67. https://doi.org/10.1080/21564574.2021.1886185
Maritz, B., E. Hofmann, R. A. Maritz, H. W. Greene, and A. Durso. 2021b. Challenges and opportunities in the study of snake diets. Herpetological Review 52:769-773.
Maritz, B., J. M. Barends, R. Mohammed, R. A. Maritz, and G. J. Alexander. 2021c. Repeated dietary shifts in elapid snakes (Squamata: Elapidae) revealed by ancestral state reconstruction. Biological Journal of the Linnean Society 134:975-986. https://doi.org/10.1093/biolinnean/blab115
Maritz, R. A., and B. Maritz. 2020. Sharing for science: high-resolution trophic interactions revealed rapidly by social media. PeerJ 8:e9485. https://doi.org/10.7717/peerj.9485
Marques, O. A. V., and I. Sazima. 2004. História natural dos répteis da estacão ecológica Juréia-Itatins. Pages 257-277 in O.A.V. Marques and V. Duleba, editors. Estação Ecológica Juréia-Itatins, ambientes físico, lora e fauna. Holos, Ribeirão Preto, Sao Paulo, Brazil.
Marques-Santos, F., T. V. Braga, U. Wischhoff, and J. J. Roper. 2015. Breeding biology of passerines in the subtropical Brazilian Atlantic Forest. Ornitologia Neotropical 26:363-374.
Martins, M., and M. E. Oliveira. 1998. Natural history of snakes in forests of the Manaus region, Central Amazonia, Brazil. Herpetological Natural History 6:78-150.
Mason, P. 1985. The nesting biology of some passerines of Buenos Aires, Argentina. Ornithological monographs 36:954-972. https://doi.org/10.2307/40168328
Mekonnen, A., C. Downs, E. O. Effiom, M. Kibaja, M. J. Lawes, P. Omeja, F. M. Ratsoavina, O. Razafindratsima, D. Sarkar, N. Stenseth, and C. A. Chapman. 2021. Can I afford to publish? A dilemma for African scholars. Ecology Letters 25:711-715. https://doi.org/10.1111/ele.13949
Menezes, J. C., and M. Â. Marini. 2017. Predators of bird nests in the Neotropics: a review. Journal of Field Ornithology 88:99-114. https://doi.org/10.1111/jofo.12203
Miranda, E. B. P., R. P. Ribeiro‐Jr, B. F. Camera, M. Barros, J. Draque, P. Micucci, T. Waller, and C. Strüssmann. 2017. Penny and penny laid up will be many: large yellow anacondas do not disregard small prey. Journal of Zoology 30:301-309. https://doi.org/10.1111/jzo.12417
Monrós J. S. 1997. El dominio vital y algunos aspectos de la ecología de la culebra bastarda Malpolon monspessulanus en los naranjales. Ph.D. thesis. University of Valencia, Valencia, Spain.
Moosavi, S. M. H., B. Behrouzi-Rad, and S. M. Amini-Nasab. 2011. Reproductive biology and breeding success of the Common Babbler Turdoides caudatus in Khuzestan Province, southwestern Iran. Podoces 6:72-79.
Mori, A., and E. Nagata. 2016. Relying on a single anuran species: feeding ecology of a snake community on Kinkasan Island, Miyagi Prefecture, Japan. Current herpetology 35:106-114. https://doi.org/10.5358/hsj.35.106
Morrison, S. A., and D. T. Bolger. 2002. Lack of an urban edge effect on reproduction in a fragmentation‐sensitive sparrow. Ecological Applications 12:398-411. https://doi.org/10.1890/1051-0761(2002)012[0398:LOAUEE]2.0.CO;2
Mortensen, H. S., Y. L. Dupont, and J. M. Olesen, J. M. 2008. A snake in paradise: disturbance of plant reproduction following extirpation of bird flower-visitors on Guam. Biological Conservation 141:2146-2154. https://doi.org/10.1016/j.biocon.2008.06.014
Najbar, B. 2007. Food habits of Zamenis longissimus (Laurenti, 1768) (Reptilia: Serpentes: Colubridae) in Bieszczady (south-eastern Poland). Vertebrate Zoology 57:73-77.
Nalwanga, D., P. Lloyd, M. A. du Plessis, and T. E. Martin. 2004. The influence of nest-site characteristics on the nesting success of the Karoo Prinia (Prinia maculosa). Ostrich Journal of African Ornithology 75:269-274. https://doi.org/10.2989/00306520409485454
Naulleau, G., and X. Bonnet. 1995. Reproductive ecology, body fat reserves and foraging mode in females of two contrasted snake species: Vipera aspis (terrestrial, viviparous) and Elaphe longissima (semi-arboreal, oviparous). Amphibia-Reptilia 16:37-46. https://doi.org/10.1163/156853895X00172
Nelson, S., R. S. Kostecke, and D. A. Cimprich. 2006. Opheodrys aestivus (rough green snake). Predation. Herpetological Review 37:234-234.
Newman, A. 1965. Further observations from Umtali Snake Park. Journal of the Herpetological Association of Rhodesia 23:55-57. https://doi.org/10.1080/0440730X.1965.9650555
Norton, R. L. 1993. Alsophis portoricensis richardi (ground snake). Feeding. Herpetological Review 24:34-34.
Olivier, A. 2020. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/3330068853695611 (Accessed 30 August 2021).
Olson, D. E., and R. E. Warner. 2001. Grassland snakes. Diet. Herpetological Review 32:186-187.
Ormand, B. 2019. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/598058350694945 (Accessed 30 August 2021).
Ortiz-Catedral, L., E. Christian, M. J. A. Skirrow, D. Rueda, C. Sevilla, K. Kirtana, E. M. R. Reyes, and J. C. Daltry. 2019. Diet of six species of Galapagos terrestrial snakes (Pseudalsophis spp.) inferred from fecal samples. Herpetology Notes 12:701-704.
Orzechowski, S. C., C. M. Romagosa, and P. C. Frederick. 2019. Invasive Burmese pythons (Python bivittatus) are novel nest predators in wading bird colonies of the Florida Everglades. Biological Invasions 21:2333-2344. https://doi.org/10.1007/s10530-019-01979-x
Ottenwalder, J. A. 1980. Epicrates striatus como predador de aves. Naturalista Postal 1980:1-2.
Otto, M. 2020. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/2793981813970987 (Accessed 30 August 2021).
Pemberton, J. R., and H. W. Carriger. 1916. Snakes as nest robbers. Condor 18:233-233.
Pennell, M. W., J. M. Eastman, G. J. Slater, J. W. Brown, J. C. Uyeda, R. G. FitzJohn, M. E. Alfaro, and L. J. Harmon. 2014. geiger v2. 0: an expanded suite of methods for fitting macroevolutionary models to phylogenetic trees. Bioinformatics 30:2216-2218. https://doi.org/10.1093/bioinformatics/btu181
Pienaar, U. D. V. 1969. Observations on the nesting habits and predators of breeding colonies of Red-billed Queleas Quelea quelea lathami (A. Smith) in the Kruger National Park. Bokmakierie 21:11-15.
Pierce, A. J., and K. Pobprasert. 2007. A portable system for continuous monitoring of bird nests using digital video recorders. Journal of Field Ornithology 78:322-328. https://doi.org/10.1111/j.1557-9263.2007.00119.x
Pierce, A. J., and K. Pobprasert. 2013. Nest predators of Southeast Asian evergreen forest birds identified through continuous video recording. Ibis 155:419-423. https://doi.org/10.1111/ibi.12033
Pitman, C. R. S. 1958a. Snake and lizard predators of birds. Part I. Bulletin of the British Ornithologist's Club 78:82-86.
Pitman, C. R. S. 1958b. Snake and lizard predators of birds. Part II. Bulletin of the British Ornithologist's Club 78:99-104.
Pitman, C. R. S. 1962a. More snake and lizard predators of birds. Part I. Bulletin of the British Ornithologist's Club 82:33-40.
Pitman, C. R. S. 1962b. More snake and lizard predators of birds. Part II. Bulletin of the British Ornithologist's Club 82:45-55.
Pitman, C. R. S. 1974. A guide to the snakes of Uganda. Wheldon and Wesley, London, UK.
Pizzatto, L., S. M. Almeida-Santos, and R. Shine. 2007. Life‐history adaptations to arboreality in snakes. Ecology 88:359-366. https://doi.org/10.1890/0012-9658(2007)88[359:LATAIS]2.0.CO;2
Pleguezuelos, J. M., J. R. Fernández-Cardenete, S. Honrubia, M. Feriche, and C. Villafranca. 2007. Correlates between morphology, diet and foraging mode in the ladder snake Zamenis scalaris (Schinz, 1822). Contributions to Zoology 76:179-186. https://doi.org/10.1163/18759866-07603003
Pryke, S. R., and M. J. Lawes. 2004. Female nest dispersion and breeding biology of polygynous Red-collared Widowbirds (Euplectes ardens). Auk 121:1226-1237.
R Core Team. 2021. R: A language and environments for statistical computing. R Foundation for Statistical Computing, Vienna, Austria
Reidy, J. L., and F. R. Thompson III. 2012. Predatory identity can explain nest predation patterns. Video Surveillance of Nesting Birds 43:135-148. https://doi.org/10.1525/california/9780520273139.003.0011
Revell, L. J. 2012. Phytools: an R package for phylogenetic comparative biology (and other things). Methods of Ecology and Evolution 3:217-223. https://doi.org/10.1111/j.2041-210X.2011.00169.x
Ribic C. A., F. R. Thomson III, and P. J. Pietz. 2012. Video surveillance of nesting birds. University of California Press, San Diego, California, USA. https://doi.org/10.1525/9780520954090
Rice, B. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/849001695600608 (Accessed 30 August 2021).
Rice, C. S., and B. Hayes. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/946643872503056 (Accessed 30 August 2021).
Riehl, C., and L. Jara. 2009. Natural history and reproductive biology of the communally breeding Greater Ani (Crotophaga major) at Gatún Lake, Panama. Wilson Journal of Ornithology 121:679-687. https://doi.org/10.1676/09-017.1
Rivard, D. H. 1976. Biology and conservation of eastern fox snakes. Elaphe vulpine gloydi Conant. Ph.D. thesis, Carleton University, Ottawa, Ontario, Canada.
Robinson, W. D., and T. R. Robinson. 2001. Observations of predation events at bird nests in central Panama. Journal of Field Ornithology 72:43-48. https://doi.org/10.1648/0273-8570-72.1.43
Robinson, W. D., G. Rompré, and T. R. Robinson. 2005. Videography of Panama bird nests shows snakes are principal predators. Ornitologia Neotropical 16:187-195.
Rodríguez-Robles, J. A. 1998. Alternative perspectives on the diet of gopher snakes (Pituophis catenifer, Colubridae): literature records versus stomach contents of wild and museum specimens. Copeia 1998:463-466. https://doi.org/10.2307/1447442
Rodríguez-Robles, J. A. 2002. Feeding ecology of North American gopher snakes (Pituophis catenifer, Colubridae). Biological Journal of the Linnean Society 77:165-183. https://doi.org/10.1046/j.1095-8312.2002.00098.x
Rodríguez-Robles, J. A., and J. M. de Jesus-Escobar. 1999. Molecular systematics of New World lampropeltinine snakes (Colubridae): implications for biogeography and evolution of food habits. Biological Journal of the Linnean Society 68:355-385. https://doi.org/10.1111/j.1095-8312.1999.tb01176.x
Root, S. T., J. Sechrist, and D. Ahlers. 2015. Pituophis catenifer affinis (Sonoran gophersnake). Diet. Herpetological Review 46:276-276.
Rowan, M. K. 1983. The doves, parrots, louries, and cuckoos of southern Africa. Croom Helm, London, UK.
Rowan, M. K., and G. J. Bruekhusen. 1962. A study of the Karoo Prinia. Ostrich Journal of African Ornithology 33:6-30. https://doi.org/10.1080/00306525.1962.9633429
Rudolph, D., S. J. Burgdorf, R. N. Conner, C. S. Collins, D. Saenz, R. R. Scaefer, T. Trees, M. C. Duran, and M. Ealy. 2002. Prey handling and diet of Louisiana pine snakes (Pituophis ruthveni) and black pine snakes (P. melanoleucus lodingi), with comparisons to other selected Colubrid snakes. Herpetological Natural History 9:57-62.
Savidge, J. A. 1988. Food habits of Boiga irregularis, an introduced predator on Guam. Journal of Herpetology 22:275-282. https://doi.org/10.2307/1564150
Schick, W. S. 2019. Snakes of southern Africa. https://www.facebook.com/groups/snakesofsouthafrica/permalink/10157376302126043 (Accessed 30 August 2021).
Schmidt, B. K., and W. R. Branch. 2005. Nest and eggs of the Black-headed Bee-eater (Merops breweri) in Gabon, with note on other Bee-eaters. Ostrich Journal of African Ornithology 76:80-81.:
Schmidt, K. P., H. Lang, and J. P. Chapin. 1923. Contributions to the herpetology of the Belgian Congo based on collections of the American Museum Congo expedition, 1905-1915. Part II: Snakes. Bulletin of the American Natural History Museum 49: 1-155.
Schramer, T. 2019. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/636979603469486 (Accessed 30 August 2021).
Schulz, K. D. 1988. Contribution to the knowledge of Elaphe schrencki (Strauch, 1873). Litteratura Serpentium 8:213-224.
Schwartz, A., and R. W. Henderson. (1991). Amphibians and reptiles of the West Indies: descriptions, distributions, and natural history. University Press, Gainesville, Florida, USA.
Scott, N. J. 1983. Conophis lineatus (guarda camino). Pages 392-393 in D. Janzen, editor. Costa Rican Natural History. University of Chicago Press, Chicago, Illinois, USA.
Şekercioğlu Ç. H., D. G. Wenny, and C.J. Whelan, C. J. 2016. Why birds matter: avian ecological function and ecosystem services. University of Chicago Press, Chicago, Illinois, USA. https://doi.org/10.7208/chicago/9780226382777.001.0001
Selman, R. G., M. L. Hunter, and M. R. Perrin. 2000. Rüppell's Parrot: status, ecology and conservation biology. Ostrich Journal of African Ornithology 71:347-348. https://doi.org/10.1080/00306525.2000.9639955
Selman, R.G. 1998. Ruppell’s Parrot: its trade, ecology and conservation. Ph.D. thesis, University of Natal, Durban, Kwa-Zulu Natal, South Africa.
Sexton, O. J., and H. Heatwole. 1965. Life history notes on some Panamanian snakes. Caribbean Journal of Science 5:39-43.
Sharp, S. J., and C, Angelini. 2021. Predators enhance resilience of a saltmarsh foundation species to drought. Journal of Ecology 109:975-986. https://doi.org/10.1111/1365-2745.13525
Shellabarger, S. S. 2019. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/594764704357643 (Accessed 30 August 2021).
Shine, R. 1987a. Ecological comparisons of island and mainland populations of Australian tigersnakes (Notechis: Elapidae). Herpetologica 43:233-240.
Shine, R. 1987b. The evolution of viviparity: ecological correlates of reproductive mode within a genus of Australian snakes (Pseudechis: Elapidae). Copeia 1987:551-563.
Shine, R. 1991a. Why do larger snakes eat larger prey items? Functional Ecology 5:493-502. https://doi.org/10.2307/2389631
Shine, R. 1991b. Strangers in a strange land: ecology of the Australian colubrid snakes. Copeia 1991:120-131. https://doi.org/10.2307/1446254
Shine, R., and D. J. Slip. 1990. Biological aspects of the adaptive radiation of Australasian pythons (Serpentes: Boidae). Herpetologica 46:283-290.
Shine, R., and M. Fitzgerald. 1996. Large snakes in a mosaic rural landscape: the ecology of carpet pythons Morelia spilota (Serpentes: Pythonidae) in coastal eastern Australia. Biological Conservation 76:113-122. https://doi.org/10.1016/0006-3207(95)00108-5
Shine, R., W. R. Branch, J. K. Webb, P. S. Harlow, T. Shine, and J. S. Keogh. 2007. Ecology of cobras from southern Africa. Journal of Zoology 272:183-193. https://doi.org/10.1111/j.1469-7998.2006.00252.x
Skutch, A. F. 1985. Clutch size, nesting success, and predation on nests of Neotropical birds, reviewed. Ornithological monographs 1985:575-594. https://doi.org/10.2307/40168306
Slowinski, J. P. 1994. The diet of kraits (Elapidae: Bungarus). Herpetological Review 25:51-52.
Smith, C. C. D., I. Layloo, R. A. Maritz, and B. Maritz. 2019. Sexual dichromatism does not translate into sex‐based difference in morphology or diet for the African boomslang. Journal of Zoology 308:253-258. https://doi.org/10.1111/jzo.12670
Smith, L. 2017. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/217024078798376 (Accessed 30 August 2021).
Solis, J. C., and F. De Lope. 1995. Nest and egg crypsis in the ground-nesting Stone Curlew Burhinus oedicnemus. Journal of Avian Biology 26:135-138. https://doi.org/10.2307/3677062
Somsiri, K., G. A. Gale, A. J. Pierce, D. Khamcha, and W. Sankamethawee. 2019. Habitat structure affects nest predation of the Scaly-crowned Babbler (Malacopteron cinereum) by macaques and snakes in a Thai-seasonal evergreen forest. Journal of Ornithology 161:1-10. https://doi.org/10.1007/s10336-019-01724-0
Sorace, A., C. Consiglio, F. Tanda, E. Lanzuisi, A. Cattaneo, and D. Iavivoli. 2000. Predation by snakes on eggs and nestlings of Great Tit Parus major and Blue Tit P. caeruleus. Ibis 142:328-330. https://doi.org/10.1111/j.1474-919X.2000.tb04875.x
Sotherland, P. R., and H. Rahn. 1987. On the composition of bird eggs. Condor 89:48-65. https://doi.org/10.2307/1368759
Spawls, S., K. Howell, H. Hinkel, and M. Menegon. 2018. Field guide to East African reptiles. Bloomsbury Publishing, London, UK.
Stake, M. M. 2001. Predation by a Great Plains rat snake on an adult female Golden-cheeked Warbler. Wilson Bulletin 113:460-461. https://doi.org/10.1676/0043-5643(2001)113[0460:PBAGPR]2.0.CO;2
Stake, M. M., and D. A. Cimprich. 2003. Using video to monitor predation at Black-capped Vireo nests. Condor 105:348-357. https://doi.org/10.1093/condor/105.2.348
Stake, M. M., F. R. Thompson, J. Faaborg, and D. E. Burhans. 2005. Patterns of snake predation at songbird nests in Missouri and Texas. Journal of Herpetology 39:215-222. https://doi.org/10.1670/150-04A
Stake, M. M., J. Faaborg, and F. R. Thompson. 2004. Video identification of predators at Golden-cheeked Warbler nests. Journal of Field Ornithology 75:337-344. https://doi.org/10.1648/0273-8570-75.4.337
Staller, E. L., W. E. Palmer, J. P. Carroll, R. P. Thornton, and D. C. Sisson. 2005. Identifying predators at Northern Bobwhite nests. Journal of Wildlife Management 69:124-132. target="_blank">https://doi.org/10.2193/0022-541X(2005)069<0124:IPANBN>2.0.CO;2
Stander, R. 2021. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/3722668537768972 (Accessed 30 August 2021).
Stevenson, D. J., M. R. Bolt, D. J. Smith, K. M. Enge, N. L. Hyslop, T. M. Norton, and K. J. Dyer. 2010. Prey records for the eastern indigo snake (Drymarchon couperi). Southeastern Naturalist 9:1-18. https://doi.org/10.1656/058.009.0101
Stickel, L. F., W. H. Stickel, and F. C. Schmid. 1980. Ecology of a Maryland population of black rat snakes (Elaphe o. obsoleta). American Midland Naturalist 103:1-14. https://doi.org/10.2307/2425033
Stokes, A. W. 1952. Population studies of the Ring-necked Pheasant on Pelee Island, Ontario. Wisconsin: University of Wisconsin, Madison, Wisconsin, USA.
Storchová, L., and D. Hořák. 2018. Life‐history characteristics of European birds. Global Ecology and Biogeography 27:400-406. https://doi.org/10.1111/geb.12709
Strüssmann, C., and I. Sazima. 1991. Predation on avian eggs by the boid snake, Eunectes notaeus. Herpetological Review 22:118-120.
Tarboton, W. R. 2011. Roberts nests and eggs of southern African birds: a comprehensive guide to the nesting habits of over 720 bird species in southern Africa. Jacana Media, Cape Town, Western Cape, South Africa.
Taylor, R. J., and E. D. Michael. 1971. Predation on an inland heronry in eastern Texas. Wilson Bulletin 83:172-177.
Theart, F. 2019. Predation records - reptiles and frogs (sub-Saharan Africa). https://www.facebook.com/groups/PredationRecordsReptilesandFrogsSubSaharanAfrica/permalink/2616181451751025 (Accessed 30 August 2021).
Thomas, B. T. 1984. Maguari Stork nesting: juvenile growth and behavior. The Auk 101:812-823. https://doi.org/10.2307/4086908
Thompson III, F. R., and C. A. Ribic. 2012. Conservation implications when the nest predators are known. Studies in Avian Biology 43:23-33. https://doi.org/10.1525/california/9780520273139.003.0002
Thompson III, F. R., W. Dijak, and D. E. Burhans. 1999. Video identification of predators at songbird nests in old fields. The Auk 116:259-264. https://doi.org/10.2307/4089477
Tonini, J. F. R., K. H. Beard, R. B. Ferreira, W. Jetz, and R. A. Pyron. 2016. Fully-sampled phylogenies of squamates reveal evolutionary patterns in threat status. Biological Conservation 204:23-31. https://doi.org/10.1016/j.biocon.2016.03.039
Toyama, M., N. Kotaka, and I. Koizumi. 2015. Breeding timing and nest predation rate of sympatric Scops Owls with different dietary niche breadth. Canadian journal of zoology, 93:841-847. https://doi.org/10.1139/cjz-2015-0060
Tsai, P. Y., C. J. Ko, C. Hsieh, Y. T. Su, Y. J. Lu, R. S. Lin, and M. N. Tuanmu. 2020. A trait dataset for Taiwan's breeding birds. Biodiversity Data Journal 8:e49735 https://doi.org/10.3897/BDJ.8.e49735
Uetz P., P. Freed, and J. Hošek. 2021. The reptile database. http://www.reptile-database.org (Accessed 01 July 2021)
Uhler, F. M., C. Cottam, and T. E. Clarke. 1939. Food of snakes of the George Washington National Forest, Virginia. Transactions of the North American Wildlife Conference 4:605-622.
Underhill, L. G., R. B. Sherley, B. M. Dyer, and R. J. Crawford. 2009. Interactions between snakes and seabirds on Robben, Schaapen and Meeuw Islands, Western Cape province, South Africa. Ostrich Journal of African Ornithology 80:115-118. https://doi.org/10.2989/OSTRICH.2009.80.2.10.837
US Fish and Wildlife Service (USFWS) and L. Smith. 2018. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/339187029915413 (Accessed 30 August 2021).
Van de Loock, D., and M.F. Bates. 2016. Montane egg-eater (Dasypeltis atra): diet and distribution. African Herp News 63:16-18.
Van der Westhuizen, M. 2020. Snakes of southern Africa. https://www.facebook.com/groups/snakesofsouthafrica/posts/10158569762746043 (Accessed 30 August 2021).
Vermilya, D. W., and E. Acuna. 2004. Lampropeltis alterna (gray-banded kingsnake). Herpetological Review 35:275-276.
Vice, D. S., D. L. Vice, and J. C. Gibbons. 2005. Multiple predations of wild birds by brown treesnakes (Boiga irregularis) on Guam. Micronesica 38:121-124.
Visco, D. M., and T. W. Sherry. 2015. Increased abundance, but reduced nest predation in the Chestnut-backed Antbird in Costa Rican rainforest fragments: surprising impacts of a pervasive snake species. Biological Conservation 188:22-31. https://doi.org/10.1016/j.biocon.2015.01.015
Visvanathan, A. C. 2015. Natural history notes on Elachistodon westermanni Reinhardt, 1863. Hamadryad 37:132-136.
Vitt, L. J., and L. D. Vangilder. 1983. Ecology of a snake community in northeastern Brazil. Amphibia-Reptilia 4:273-296. https://doi.org/10.1163/156853883X00148
Vogt, R. C. 1981. Natural history of amphibians and reptiles in Wisconsin. The Milwaukee Public Museum, Milwaukee, Wisconsin, USA.
Waller, T., P. A. Micucci, and E. Alvarenga. 2007. Conservation biology of the yellow anaconda (Eunectes notaeus) in northeastern Argentina. Pages 340-363 in R. W. Henderson and R. Powell, editors. Biology of the Boas and Pythons. Eagle Mountain Publishing, Eagle Mountain, Utah, USA.
Wang, J. J., Z. G. Yu, Z. M. Li, H. Jiang, and W. Liang. 2014. Identifying predators of ground nests of birds in Kuankuoshui Nature Reserve, Guizhou, southwestern China. Chinese Journal of Ecology 33:352-357.
Ward, D. 1989. Behaviour associated with breeding of crowned, blackwinged and lesser blackwinged plovers. Ostrich Journal of African Ornithology 60:141-150. https://doi.org/10.1080/00306525.1989.9633746
Weatherhead, P. J., and G. Blouin‐Demers. 2004. Understanding avian nest predation: why ornithologists should study snakes. Journal of Avian Biology 35:185-190. https://doi.org/10.1111/j.0908-8857.2004.03336.x
Weaver, R.E. 2004. Pituophis catenifer (gopher snake). Diet. Herpetological Review 35:179-180.
Wentz, C. M. 1953. Experimenting with a coral king snake. Yosemite Nature Notes 32:80-80.
Wheeler, W. E. 1984. Duck egg predation by fox snakes in Wisconsin. Wildlife Society Bulletin 12:77-78.
Whelan, C. J., Ç. H. Şekercioğlu, and D. G. Wenny. 2015. Why birds matter: from economic ornithology to ecosystem services. Journal of Ornithology 156:227-238. https://doi.org/10.1007/s10336-015-1229-y
Whelan, C. J., D. G. Wenny, and R. J. Marquis. 2008. Ecosystem services provided by birds. Annals of the New York academy of sciences 1134:25-60. https://doi.org/10.1196/annals.1439.003
Wiley, J. W. 2001. Green Heron (Butorides virescens) predation at Village Weaver (Ploceus cucullatus) nests. Journal of Caribbean Ornithology 14:130-133.
Wiley, J.W. 2003. Habitat association, size, stomach content, and reproductive condition of Puerto Rican boas (Epicrates inornatus). Caribbean Journal of Science 39:189-194.
Wilkerson, M. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/889338914900219 (Accessed 30 August 2021).
Wilson, R. 1985. Yellow Warbler nestling predation by eastern fox snake. Ontario Birds 3:73-75.
Wiseman, K. D., H. W. Greene, M. S. Koo, and D. J. Long. 2019. Feeding ecology of a generalist predator, the California kingsnake (Lampropeltis californiae): why rare prey matter. Herpetological Conservation and Biology 14:1-30.
Wishard, M., and J. Cavataio. 2020. Wild snake predation records. https://www.facebook.com/groups/wild.snake.predation.records/permalink/906220806545363 (Accessed 30 August 2021).
Yu, X., N. Liu, Y. Xi, and B. Lu. 2006. Reproductive success of the Crested Ibis Nipponia nippon. Bird Conservation International 16:325-343. https://doi.org/10.1017/S0959270906000499
Yu, X., X. Li, and Z. Huo. 2015. Breeding ecology and success of a reintroduced population of the endangered Crested Ibis Nipponia nippon. Bird Conservation International 25:207-219. https://doi.org/10.1017/S0959270914000136
Znari, M., M. Aourir, M. Radi, and J. M. Melin. 2008. Breeding biology of the Black-bellied Sandgrouse Pterocles orientalis in west-central Morocco. Ostrich Journal of African Ornithology 79:53-60. https://doi.org/10.2989/OSTRICH.2008.79.1.6.363