Environmental drivers of Cheirogaleidae population density: Remarkable resilience of Madagascar’s smallest lemurs to habitat degradation

Abstract

Aim Global animal populations are in decline due to destruction and degradation of their natural habitat. Understanding the factors that determine the distribution and density of threatened animal populations is therefore now a crucial component of their study and conservation. The Cheirogaleidae are a diverse family of small‐bodied, nocturnal lemurs that are widespread throughout the forests of Madagascar. However, many cheirogaleid lemurs are now highly threatened with extinction and the environmental factors that determine their distribution and population density are still little known. Here, I investigated the environmental drivers of Cheirogaleidae population density at genus level. Location Various forest sites across Madagascar. Methods I investigated how six environmental variables affect Cheirogaleidae population density at the genus level via random‐effect meta‐analyses. I then used a generalized linear mixed‐effects model to identify the primary predictors of Cheirogaleidae population density. Finally, I investigated how the population density of this family of lemurs varies between protected and unprotected areas of Madagascar via a GLM analysis. Results My results indicate that the relationships between the tested environmental factors and population density are genus‐specific among the Cheirogaleidae. Rather remarkably, the density of Microcebus appears to have a profoundly positive relationship with anthropogenic disturbance and a negative relationship with forest cover, a finding that is also reflected by larger population densities within unprotected areas in comparison with localities within Madagascar's protected area network. Main Conclusions The results of this study are highly encouraging for the conservation of the Cheirogaleidae and highlight the remarkable resilience of these lemurs to habitat degradation and anthropogenic activity. However, this study also outlines the dearth of knowledge that we have for many species, and why these data are urgently needed to understand the biogeography and ecology of threatened animal populations and implement successful conservation.

Effects of future climate change on the forests of Madagascar

“…A net loss of dry forest, humid forest, and spiny bush is predicted to occur under an unmitigated future climate scenario, and contraction of these habitats will be disastrous for animals endemic to these habitat types, which are already severely impacted by deforestation and anthropogenic pressures (Harper et al, 2007; Vieilledent et al, 2018). Climatic shifts will result in microclimatic and microhabitat shifts within the different forest types, and while some of Madagascar's animals are tolerant of environmental change (Hending, 2021b), this will almost certainly impact species with narrow ecological niches (Liu et al, 2020). This is likely to be most profound in humid forests, where lengthening of the dry season will affect availability of vegetation and soil invertebrates, which will subsequently affect the animals that feed upon them.…”

Anthropogenic disturbance impacts gut microbiome homeostasis in a Malagasy primate

“…Despite major conservation efforts, Madagascar’s unique ecosystems are declining at a vast speed, threatening the home of many endemic lemur species. Whereas most lemur species are highly sensitive to anthropogenic change, others, including our focus species, which is one of the smallest Malagasy primates, namely the grey-brown mouse lemur, ( M. griseorufus ), seem at the first glance to be more resilient, since they can also inhibit human-modified habitats (Hending, 2021). However, whether such resilience also applies to its inner ecosystem, the gut microbiome, remains unknown.…”

“…In the dry season when the food supply is short, the lemur reduces its metabolic activities and enters torpor or a hibernation-like stage (Mittermeier et al 2010). Small-bodied primates and nocturnal primates have been suggested to be less sensitive to anthropogenic disturbances (Eppley et al, 2020;Hending, 2021).…”

“…In the dry season when the food supply is short, the lemur reduces its metabolic activities and enters torpor or a hibernation-like stage (Mittermeier et al 2010). Small-bodied primates and nocturnal primates have been suggested to be less sensitive to anthropogenic disturbances (Eppley et al, 2020; Hending, 2021). Nevertheless, anthropogenically modified habitats with substantial contact zones between lemurs and humans increase disturbance frequencies and modify habitat and microclimatic characteristics, including food resources.…”

Thirty years of deforestation within the entire ranges of nine endangered lemur species (3 CR, 4 EN, 2 VU) in northwestern Madagascar

“…For the majority of lemur species, the population-wide influence of habitat loss and fragmentation is not well investigated yet (Hending 2021, Kling et al 2020). For those species having parts of their distributions inside Ankarafantsika NP (in IRS I), the proportion of available habitat was relatively stable in its extent until 2021.…”