THERMAL CONSTRAINTS ON SWIMMING PERFORMANCE AND ESCAPE RESPONSE OF NORTHERN WATER SNAKES (NERODIA-SIPEDON)

Citation
Pj. Weatherhead et Ic. Robertson, THERMAL CONSTRAINTS ON SWIMMING PERFORMANCE AND ESCAPE RESPONSE OF NORTHERN WATER SNAKES (NERODIA-SIPEDON), Canadian journal of zoology, 70(1), 1992, pp. 94-98
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Zoology
Journal title
ISSN journal
0008-4301
Volume
70
Issue
1
Year of publication
1992
Pages
94 - 98
Database
ISI
SICI code
0008-4301(1992)70:1<94:TCOSPA>2.0.ZU;2-P
Abstract
We examined the influence of body temperature on swimming speed of nor thern water snakes (Nerodia sipedon) and determined how variation in w ater temperature influenced their escape response. In a laboratory exp eriment, swimming speed increased as a function of water temperature a nd body size. Swimming speed was less thermally dependent at temperatu res approximating the snakes' normal range of activity, suggesting tha t selection has favoured increased performance breadth at this range. In the field, basking snakes retreated to water when approached. Despi te a decrease in swimming speed at lower temperatures, and the cost as sociated with reduced metabolic rate due to loss of body temperature, however, flight distances were independent of water temperature. We fo und that basking snakes retreated to water sooner when perched at lowe r heights, possibly indicating that N. sipedon are more vulnerable to predators when on low perches. Predicting water snake escape behaviour may require not only knowledge of variation both among snakes and in their environment, but also a better understanding of the interaction between the snakes and their natural predators.