About this Environmental Science article

Variable Age Structure and Apparent Density Dependence in Survival of Adult Ungulates by Marco Festa-Bianchet; Jean-Michel Gaillard; Steeve D. Côté is a Environmental Science article available to read on EtoBox.

## Summary Large herbivores have strongly age‐structured populations. Because recruitment often decreases as population density increases, in unexploited populations the proportion of older adults may increase with density. Because survival senescence is typical of ungulates, ignoring density‐dependent changes in age structure could lead to apparent density‐dependence in adult survival. To test for density dependence in adult survival, we used data from three populations that underwent considerable changes in density. Bighorn sheep (__Ovis canadensis__) on Ram Mountain, Alberta, ranged from 94 to 232, mountain goats (__Oreamnos americanus__) on Caw Ridge, Alberta, varied from 81 to 147, and estimates of roe deer (__Capreolus capreolus__) older than 1 year at Chizé, France, ranged from 157 to 569. We used recent developments of capture–mark–recapture modelling to assess the response of adult survival to changes in density when age structure was and was not taken into account. Survival rates were 10–15% higher during the prime‐age stage than during the senescent stage for all sex‐species combinations. When adults were pooled into a single age class there was an apparent negative effe

Author

Marco Festa-Bianchet; Jean-Michel Gaillard; Steeve D. Côté

Publisher

John Wiley and Sons; Wiley (Blackwell Publishing); Blackwell Publishing Inc.; Wiley; JSTOR (ISSN 0021-8790)

Published

2003

Language

EN

Field

Environmental Science (Physical Sciences)