Variations in adult body mass in roe deer: the effects of population density at birth and of habitat quality

Abstract

Body mass is a key determinant of fitness components in many organisms, and adult mass varies considerably among individuals within populations. These variations have several causes, involve temporal and spatial factors, and are not yet well understood. We use long-term data from 20 roe deer cohorts in a 2600 ha study area (Chizé, western France) with two habitats contrasting in quality (rich oak forest in the North versus poor beech forest in the South) to analyse the effects of both cohort and habitat quality on adult mass (i.e. median body mass between 4 and 10 years of age) of roe deer (Capreolus capreolus). Cohort strongly influenced the adult body mass of roe deer in both sexes: males born in 1994 were 5.2 kg heavier when aged between 4 and 10 years old than males born in 1986, while females born in 1995 were 4.7 kg heavier between 4 and 10 years old than females born in 1982. For a given cohort, adult males were, on average, 0.9 kg heavier in the rich oak forest than in the poor beech forest. A similar trend occurred for adult females (0.5 kg heavier in the oak forest). The effects of cohort and habitat were additive and accounted for ca. 40% of the variation observed in the adult mass of roe deer at Chizé (males: 41.2%; females: 40.2%). Population density during the spring of the birth accounted for about 35% of cohort variation, whereas rainfall in May-June had no effect. Such delayed effects of density at birth on adult body mass probably affect population dynamics, and might constitute a mechanism by which delayed density-dependence occurs in ungulate populations.

Population density and sex do not influence fine-scale natal dispersal in roe deer

“…changes in the number of animals removed for translocation). At Chizé, density-dependent responses have been reported for early growth (Hewison et al 2002), fawn body mass (Gaillard et al 1996), fawn survival (Gaillard et al 1997), the proportion of young females successfully breeding (Gaillard et al 1992) and adult body mass (Pettorelli et al 2002 (Kjellander et al 2004). At Dourdan and Chizé, the climate is mild, with an average winter temperature greater than 3.58C and a yearly average of less than 5 days winter snow lie.…”

Emigration and Density Dependence in Yellowstone Bison

“…Similarly, production of a proportionally large calf cohort in year t could have increased intraspecific competition. Undernourishment during development could have caused such cohorts to be in poor physical condition upon primiparity, leading to reduced recruitment and a low calf : cow ratio in year t + 3 (Descamps et al 2008;Hamel et al 2009;Pettorelli et al 2002). To account for these possible cohort effects on the HM calf : cow ratios, we considered autoregressive terms up to order 3 (i.e., the effects of calf : cow ratios at t 2 1, t 2 2, and t 2 3 on the calf : cow ratio at time t).…”

Ecological correlates of home‐range size in spring–summer for female roe deer (Capreolus capreolus) in a deciduous woodland

“…The climate is oceanic with mild winters and hot, dry summers. The dominant trees are deciduous, and detailed information about the Chizé forest is available in Gaillard, Delorme, Boutin et al (1993) and Pettorelli, Gaillard, Van Laere et al (2002). Principal food plants for roe deer in spring and summer are oak Quercus sp., hornbeam Carpinus betulus, maple Acer campestris, hawthorn Crataegus monogyna, and dogwood Cornus sp.…”