PARENT SESSION
Contributed Oral Session 17: Reptiles and Amphibians: Habitat; and Communities
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal

Effects of forest harvesting and food limitation on body condition of juvenile and adult northwestern salamanders (Ambystoma gracile).

Hilton, Alana^*,1, Richardson, John¹, ¹ University of British Columbia, Vancouver, British Columbia, Canada

ABSTRACT- Forest harvesting alters microclimate, which may affect amphibians directly, as well as affect the abundance, diversity and/or availability of amphibian prey. As a result, the foraging efficiency of amphibians in harvested areas may be reduced, lowering body condition, and perhaps survival. We experimentally tested the hypotheses that: 1) body condition would be lower in clearcuts than forested sites; and 2) salamanders would be food limited in clearcuts but not in forest, and food addition to clearcut enclosures would improve body condition, while food addition to forest enclosures would have no effect. We used 24 large-scale field enclosures in a 2 by 2 factorial design with forest type (clearcut, forested; each n = 3) and food level (supplemental mealworms, ambient) as factors to examine the effects on body condition of adult and juvenile northwestern salamanders. In trial one, which started in October 2003, each of the 24 enclosures received 14 marked and measured juveniles. Juveniles were recaptured and re-measured in April/May 2004. In trial two, each of the enclosures received 7 marked and measured adult salamanders in May 2004, and adults were recaptured and re-measured in October/November 2004. Mealworms were added weekly to half the enclosures at each site. We used a mixed model analysis of covariance (initial body condition as covariate) to determine the effects of forest type, food level, and site within forest type on final body condition. Results indicated no significant effect of forest type or food level on body condition of juveniles or adults. However, for juveniles, there was a significant effect of the interaction between food level and site nested in forest type for body condition (p<0.01) and proportion recaptured (p<0.01), illustrating the importance of individual sites. For adults, there was a significant effect of forest type on the proportion recaptured (p<0.02), with fewer animals recaptured in clearcut enclosures.

Key words: amphibians, forest harvesting, body condition, food limitation