Does habitat disturbance affect stress, body condition and parasitism in two sympatric lemurs?

Josué H Rakotoniaina,Juliane Grass,Anni M Hämäläinen,Peter M Kappeler,Pascaline Ravoniarimbinina,Clemens Kirschbaum,Cornelia Kraus,Eva Pechouskova

doi:10.1093/conphys/cow034

Abstract

Understanding how animals react to human-induced changes in their environment is a key question in conservation biology. Owing to their potential correlation with fitness, several physiological parameters are commonly used to assess the effect of habitat disturbance on animals’ general health status. Here, we studied how two lemur species, the fat-tailed dwarf lemur (Cheirogaleus medius) and the grey mouse lemur (Microcebus murinus), respond to changing environmental conditions by comparing their stress levels (measured as hair cortisol concentration), parasitism and general body condition across four habitats ordered along a gradient of human disturbance at Kirindy Forest, Western Madagascar. These two species previously revealed contrasting responses to human disturbance; whereas M. murinus is known as a resilient species, C. medius is rarely encountered in highly disturbed habitats. However, neither hair cortisol concentrations nor parasitism patterns (prevalence, parasite species richness and rate of multiple infections) and body condition varied across the gradient of anthropogenic disturbance. Our results indicate that the effect of anthropogenic activities at Kirindy Forest is not reflected in the general health status of both species, which may have developed a range of behavioural adaptations to deal with suboptimal conditions. Nonetheless, a difference in relative density among sites suggests that the carrying capacity of disturbed habitat is lower, and both species respond differently to environmental changes, with C. medius being more negatively affected. Thus, even for behaviourally flexible species, extended habitat deterioration could hamper long-term viability of populations.

Highlights

Habitat loss and degradation as a result of anthropogenic activities are major causes of species decline, and identifying their effect on the health and viability of wildlife populations is pivotal to conservation biology (Wikelski and Cooke, 2006; Acevedo-Whitehouse and Duffus, 2009)
This study demonstrates that moderate human disturbance may have negligible influence on the general health status of species that are capable of adjusting to suboptimal conditions by behavioural or dietary flexibility
Health parameters are often easier to measure than population density or population decline, the present study emphasizes the degree of uncertainty associated with such shortcuts

Summary

Introduction

Habitat loss and degradation as a result of anthropogenic activities are major causes of species decline, and identifying their effect on the health and viability of wildlife populations is pivotal to conservation biology (Wikelski and Cooke, 2006; Acevedo-Whitehouse and Duffus, 2009). Anthropogenic disturbances can negatively affect individuals’ general health status; for instance, by altering resource availability, enhancing predation and hunting pressure or facilitating the spread of parasites (Keyser et al, 1998; Allan et al, 2003; Rode et al, 2006) Despite this general trend, the sensitivity of. Despite the considerable utility of this approach for conservation biologists, it remains extremely arduous to predict how a given species will respond to disturbances or even to identify the intrinsic factors that can potentially initiate a population decline (Wasser et al, 1997; but see Creel et al, 2002) This difficulty is attributable to the fact that such a complex phenomenon is likely to involve multiple explanatory factors, as indicated by several long-term studies (Gulland, 1992; Milton, 1996), highlighting the need for using multiple indicators in health assessment studies

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