Why Did the Snapper Cross the Road?

February 6, 2014

Nature Notes by Bill Dunson

A popular TV show details the exploits of a Kentucky legend the “Turtleman,” who attempts to save snapping turtles and other animals from troubles with modern society. One of my former students at Penn State sent me an interesting story about a somewhat similar exploit which occurred after he found a snapper making a nest and laying eggs on the side of a busy road. He recovered them, incubated the eggs, and later released the hatchlings at a more desirable location. Is it a good idea to interfere in this way with nature? What if the alternative is that the eggs and young will almost certainly die? But what if by being a good Samaritan you propagate the genes that led this female to make a nest in an inappropriate place? A very similar argument is made about rescuing sea turtle nests laid too low on the beach.

The common snapping turtle is not a critter that is easy to love. It is all “claws and jaws” and ready for a fight at any time. It is widespread in aquatic habitats throughout the eastern and mid-western US. It is often suspected of eating more desirable aquatic life such as fish and ducks but this has rarely been found to be a significant problem. I built a number of ponds on our VA farm and was not happy to find snappers rapidly colonizing them by moving up the creeks. You can trap them and even eat them, but you will never be without snappers for long. They are survivors from the antediluvian ages and can have a life span similar to humans, so I have learned to appreciate their toughness and tenacity. Of course their ability to reproduce is countered by a host of animals, primarily mammals, that eat their eggs.

So if you decide to save a clutch of turtle eggs and incubate them, how exactly do you proceed? A major issue has to do with the temperature of incubation, which in reptiles often determines the sex of the hatchlings. The effect of temperature on sex is surprisingly complex in snappers, with mainly females at the highest and lowest temperatures. Female snappers prefer to lay their eggs in disturbed ground that is open and without vegetation and may walk a long way to find suitable nesting habitat. This yields a higher temperature and a quicker incubation, but such areas in the modern world are often roadways or agricultural fields which are dangerous for a nest. The good news is that snappers live a long time and can nest repeatedly and will hopefully be successful occasionally in producing progeny.

Despite their ferocious nature, snappers and other turtles do need our help to survive the perils of a modern world. So I salute those who offer some protection when they see turtles crossing the road or nesting in a dangerous spot. The primary need is to save adult females from premature death, for example on roads or by over-exploitation by trappers. Protection of the eggs from predation by skunks, armadillos, foxes, coyotes, etc. can be achieved by placing a wire cage around the nest and removing it when the eggs hatch. In most cases this would be preferable to digging up the eggs and incubating them artificially. Predator control in areas where a lot of nesting occurs is another alternative to reduce the population of mammals that specialize in feeding on turtle eggs. But too much interference with nature can sometimes be worse than the original problem. So my advice is, in so far as possible, to let natural events occur, but I find no easy answers.

Bill Dunson

Bill Dunson

About Bill Dunson

Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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