Egg predation and vertebrates associated with wild crocodilian nests in Mexico determined using camera-traps

Fauna Associated with American Alligator (Alligator mississippiensis) Nests in Coastal South Carolina, USA

“…Similar to our findings, these species all fed directly on invertebrates associated with nests or used nest mounds as staging grounds to feed in nearby water [10]. Further, González-Desales et al [11] reported feeding by 8 of 11 (72.7%) avian species photographed at nest mounds of Morelet's crocodiles (Crocodylus moreletii) in Mexico. Although several species of birds (primarily crows, ravens, and vultures; [50,51]) are known to feed on crocodilian eggs, and egg consumption by some wrens has been documented [52], our observation of a Carolina wren feeding on the contents of a recently predated alligator egg is, to the best of our knowledge, the first report of egg consumption by this species and the first record of crocodilian egg consumption by a passerine.…”

“…Although several species of birds (primarily crows, ravens, and vultures; [50,51]) are known to feed on crocodilian eggs, and egg consumption by some wrens has been documented [52], our observation of a Carolina wren feeding on the contents of a recently predated alligator egg is, to the best of our knowledge, the first report of egg consumption by this species and the first record of crocodilian egg consumption by a passerine. Despite loafing being one of the primary activities exhibited by birds at alligator nests in our study, this behavior has not been reported for birds in previous studies of crocodilian nest associates [10][11][12]. However, this may be due to differences in the way feeding/foraging behavior was defined among the studies; in our study, activities such as sitting and standing (when not associated with probing, digging, and pursuing/consuming prey) were categorized as loafing, while in other studies, these activities may have been considered components of feeding/foraging behavior.…”

“…Most reptiles photographed in this study were observed traveling across the nest site and basking on nests, although some individuals (i.e., banded watersnakes and ribbon snakes) were seen feeding/foraging (pursuing prey). Basking was also a predominant behavior exhibited by reptiles on alligator nests in Louisiana and Texas [10] and Morelet's crocodile nests in Mexico [11]. In addition, all reptiles observed in the former study [10] also used alligator nests as egg deposition sites.…”

“…McIlhenny [15] (p. 89) noted that "nests of alligators are robbed for their eggs" by opossums, but it is unclear if he observed opossums excavating clutches or scavenging eggs after nests were opened by other predators. González-Desales et al [11] recently reported predation of Morelet's crocodile eggs by a Virginia opossum, but in this case, the opossum took eggs from the nest after it had been previously opened by a raccoon. To the best of our knowledge, our study is the first report of Virginia opossums opening intact alligator nests and removing eggs for consumption.…”

“…Open holes, dens, and tunnels excavated by crocodilians to escape unfavorable environmental conditions and predators serve as reservoirs of fresh water, especially critical during periods of drought or in coastal habitats where other fresh water sources are scarce [2,[5][6][7][8][9]. Mound-nesting species build elevated structures (nests) in otherwise flat and often flooded terrain, which can be used as nesting, feeding, and basking platforms by an array of birds, mammals, reptiles, and amphibians [2,[10][11][12]. In addition, the construction of a mound nest can result in significant habitat alteration, including a large area (3-7 m in diameter) of disturbance surrounding the mound, disrupted soil substrate, and often a guard hole or den containing water nearby [7,10,13].…”