Recent Field Research – Reptile and Amphibian Feeding Observations

Many interesting field research reports are published in professional journals such as Copeia, Herpetologica and Herpetological Review, and are not available on the internet.  From time to time I’ll provide summaries of some of the fascinating articles that I come across.  Today’s report, drawn from Autumn, 2010 publications, covers observations of free-living snakes, turtles and caimans.

Giant Meals…even for snakes!

Snakes are “big meal specialists”, but rarely consume animals larger than themselves.  However, a Southern Toad and a Spadefoot Toad, swallowed by different Eastern Hog-nosed Snakes, Heterodon platyrinos, each outweighed the snake by several grams! 

The largest snake meal I’ve personally observed was a 60 pound White-tailed Deer that was consumed by a 16 foot-long Green Anaconda, Eunectes murinus, in Venezuela.  Other notable Anaconda meals include a Red-Footed Tortoise and a Yellow-Spotted Side-Necked Turtle (please see article below for details and other observations).  However, when viewed in terms of predator vs. prey mass, the Hog-nosed Snake meals mentioned above are the largest I know of.

Aquatic Surprises

Most semi-aquatic turtles are able to swallow food only while in water, so I was most interested to read of a Chacoan River Turtle, Rhinoclemmys nasuta, that consumed carrion (the body of a Water Opossum) while on land.  The observation was made on Isla Palma, a small island off Columbia, South America.

A Spectacled Caiman, Caiman Crocodylus, in the Everglades National Park was seriously injured when it attempted to swallow a Walking Catfish (neither is native to Florida); both of the fish’s pectoral fins had pierced the Caiman’s esophagus.

Unusual Snake Meals and “Dining Places”

Longspine Sandbur Grass seed heads were found embedded in the mouth of a Prairie Rattlesnake, Crotalus viridis, in Colorado.  The plant is introduced, and its spiny seeds have also been found in the skins of snakes as well.  The seed heads were likely ingested incidentally, along with rodent prey, and would certainly have caused an infection or other problem in time.

A sidewalk at the University of Florida, Gainesville, produced an observation of an Eastern Ratsnake (“Yellow Ratsnake”), Pantherophis alleghaniensis, in the process of killing a Northern Yellow Bat.  A former co-worker of mine once came upon a huge Yellow Ratsnake in the process of constricting a new-born White-tailed Deer (St. Catherine’s Island, Georgia)…I need to re-check my notes for details, and will provide an update when possible.

Most books list typical prey items for various herps, but many species consume an astonishing variety of animals.  I’ve been lucky enough to run across a few surprises – a Black Tree Monitor consuming a House Sparrow, Marine Toads eating salad, and so on; I’ll highlight others in the future. 

 

Further Reading

Big Snake Meals: my observations and some record-breakers

Video: amazing African Egg-Eating Snake in action

Eastern Hognose Snake image referenced from wikipedia and originally posted by Patrick Coin
Northern Water Snake eating a fish image referenced from wikipedia and originally posted by FotoDawg
Eastern Hognose Snake eating a toad image referenced from wikipedia and originally posted by Dawson