Digestive move

Natural History, May, 2002 by Stephan Reebs

For a snake, there's no such thing as eating piecemeal: it gobbles its prey whole. But a complete carcass sitting in the snake's stomach may slow it down, and the prey may even start to decompose before being fully digested. So it would be advantageous for a snake with a full stomach to speed digestion by raising its body temperature. And according to observations by Gabriel Blouin-Demers and Patrick J. Weatherhead, of Carleton University in Canada, snakes do that by judiciously choosing where they go to digest their meal.

The researchers placed recently killed chipmunks, mice, and voles in the shady interior of a forest and also along its edges, which get more sun and thus afford more opportunities that fed on rodents along the forest edges tended to stay put after eating, whereas snakes that ate in the interior often moved out to the edges afterward. Individuals that had dined were seen basking more often than those that hadn't, and surgically implanted temperatures-sensitive radio transmitters reported higher body temperatures in fed than in unfed snakes. Back in the laboratory, captive black rat snakes confirmed these field observations. Offered the opportunity, these snakes, too, liked to repair to a warm spot after a good meal. ("An Experimental Test of the Link Between Foraging, Habitat Selection and Thermoregulation in Black Rat Snakes Elaphe obsoleta obsoleta," Journal of Animal Ecology 70, 2001)

Stephan Reebs is a professor of biology at the Universite de Moncton in New Brunswick, Canada. He is the author of Fish Behavior in the Aquarium and in the Wild, recently published by Cornell University Press.