Ontogenetic shifts in the diet of plains hog-nosed snakes (Heterodon nasicus) revealed by stable isotope analysis

• Published in: Zoology (Jena) 2017-02, Vol.120, p.83-91
• Main Authors: Durso, Andrew M., Mullin, Stephen J.
• Format: Article
• Language: English
• Subjects: Aging - physiology; Animals; Carbon - chemistry; Carbon Isotopes - chemistry; Community ecology; Diet - veterinary; Nitrogen - chemistry; Nitrogen Isotopes - chemistry; Prairies; Predatory Behavior - physiology; Reptiles; Snake diet; Snakes - growth & development; Snakes - physiology; Stable isotope analysis
• ISSN: 0944-2006; 1873-2720
• DOI: 10.1016/j.zool.2016.07.004

•We combined traditional methods and stable isotopes to study wild snake diets.•Heterodon nasicus shifts from eating lizards and their eggs to eating aquatic turtle eggs.•Following numerous best practices enhances the rigor of this result.•Simulation work with trophic enrichment factors suggests minimal effects. Wild snake diets are difficult to study using traditional methods, but stable isotopes offer several advantages, including integrating dietary information over time, providing data from individuals that have not fed recently, and avoiding bias towards slowly-digesting prey items. We used stable isotope signatures of carbon and nitrogen from scale tissue, red blood cells, and blood plasma to assess the diet of wild plains hog-nosed snakes (Heterodon nasicus) in Illinois. We developed Bayesian mixing models which, taken together, predicted that H. nasicus shifted from a juvenile diet predominantly (31–63%) composed of six-lined racerunners (Aspidoscelis sexlineatus) and their eggs to an adult diet predominantly (44–56%) composed of eggs of the aquatic turtles Chrysemys picta and Chelydra serpentina, with a contribution from toads (Anaxyrus sp.; 6–27%) during their adolescent years. These results agreed with sparse data from gut contents. Combining traditional and isotopic techniques for studying the diets of wild snakes can increase the utility of both types of data.