Lemurs in a complex landscape: mapping species density in subtropical dry forests of southwestern Madagascar using data at multiple levels

Abstract

The study of southern dry forest lemurs has been largely restricted to small reserves; yet, the majority of the region's lemur populations reside outside protected areas. Lemur catta and Propithecus verreauxi occupy the same forests but have different dietary preferences. This study assessed L. catta and P. verreauxi population densities across a 3-km dry forest gradient (1,539 ha) in southern Madagascar. The study was designed to allow lemur densities to be related to particular forest types. A particular aim of this study was to collect lemur data in both protected and unprotected areas. Density estimates were calculated using point transect distance sampling in a study area that contained the Beza Mahafaly Special Reserve and the adjacent disturbed forests. The highest densities recorded for each species were in the protected area where the two species were most segregated in their distribution, with L. catta density highest in gallery forest type and P. verreauxi density highest in dry deciduous. Densities of both species varied widely outside the protected area, but P. verreauxi density was more uniform than was L. catta. Results of this study indicate that patterns of lemur density in protected areas are not representative of patterns in disturbed forests; this also suggests that we cannot fully understand the ecological constraints facing primate species by studying them only in protected areas. This research highlights the value of pairing the study of landscape-level patterns of species distribution with both local ground-level ecological interpretations and broad-scale satellite data; information from only one level may give an incomplete view of the community.

Beyond the Gallery Forest: Contrasting Habitat and Diet in Lemur catta Troops at Bezà Mahafaly Special Reserve

“…As others have noted, ring-tailed lemur densities appear to be correlated with Tamarindus abundance in gallery forests [Gould et al, 2003;Blumenfeld-Jones et al, 2006], and their density has been found to be higher along the river in P1 [Axel and Maurer, 2010]. Similarly, the majority of the plant species in table 1 eaten by sifakas are found in the western half of P1 and in P2 [Yamashita, 2002], which coincides with their higher densities in those locations [Axel and Maurer, 2010].…”

“…Parcel 1 (P1) is the 80 ha deciduous tropical dry forest [Sussman and Rakotozafy, 1994] where the majority of research on lemurs at BMSR has taken place. Parcel 2 (P2) is a 520 ha plot located 5 km to the west of P1 and is composed of a patchwork of dry, deciduous forest and spiny forest [Axel and Maurer, 2010] ( fig. 1 ).…”

Primates in 21st century ecosystems: does primate conservation promote ecosystem conservation?

“…The research goal was to document lemur habitat use in both protected (Beza Mahafaly Special Reserve) and nonprotected areas in the vicinity of the reserve. Axel and Mauer [2011] found that Lemur catta (ring-tailed lemurs) occurred at highest densities in the gallery forests of the reserve. Population density of Propithecus verreauxi (sifakas) was lower but more uniform across a wide swath of drier forests.…”

“…Also in this issue, Axel and Mauer [2011] used satellite imagery to classify forest types and point transect sampling to document habitat preferences and group size variation in two species of diurnal lemurs currently inhabiting southwestern Madagascar. The research goal was to document lemur habitat use in both protected (Beza Mahafaly Special Reserve) and nonprotected areas in the vicinity of the reserve.…”

Ring-Tailed Lemur (Lemur catta) Health Parameters across Two Habitats with Varied Levels of Human Disturbance at the Bezà Mahafaly Special Reserve, Madagascar

“…1 ). Specifically, there is dramatic deforestation and evidence of livestock grazing throughout P2, yet numerous lemur troops live here [Axel and Maurer, 2011]. P2 ring-tailed lemurs have only recently been habituated to humans and thus their health status was previously unknown.…”