DOI: 10.5061/dryad.rr4xgxdg1
title: Lemur population density in Sahamalaza-Iles Radama National Park, Madagascar

description: The clearing and fragmentation of tropical forest is the single biggest
 threat to primate populations who depend on this habitat for survival. In
 contrast to primates that live in continuous, undisturbed forests, primate
 communities of fragmented forests need to adapt to decreased food
 availability and increased inter- and intraspecific competition typical of
 these degraded and anthropogenically disturbed habitats. Some primate
 species are highly sensitive to habitat fragmentation, whilst other
 species can adapt and even thrive in fragmented and degraded forests.
 Here, we assessed how forest fragmentation and associated edge-effects
 impact the population density of four species of nocturnal lemur in the
 Sahamalaza-Iles Radama National Park, North West Madagascar. We conducted
 118 transect walks over a three-year period covering a total distance of
 107 km to collect encounter rate (N/km) and population density (N/Ha) data
 for each species, which we then compared between the edge and core areas
 of a continuous forest and a fragmented forest. Our results were highly
 species-specific, with the population densities of two species (Lepilemur
 sahamalaza and Microcebus sambiranensis) increasing in edge and fragmented
 habitat, whilst we observed the opposite for Cheirogaleus medius. Mirza
 zaza density appeared consistent between the continuous and fragmented
 forest and in both edge and core areas. We also found evidence of
 species-specific population density relationships with fragment size, core
 area, and fragment shape; however, further work is needed to support these
 findings. This study demonstrates that some nocturnal lemurs can adapt to
 degraded habitats and thrive within fragmented forests, whilst other
 species are less capable of doing so.
description: This dataset contains two data sheets. The first, `Transects`, contains
 the raw transect distance sampling data. The "Individuals" sheet
 contains individual lemur observations, where each row represents a single
 lemur individual. For each individual (Observation_Number), information on
 the time of observation (Date, Time), location of observation (Forest,
 Fragment, Edge_or_Core, Transect, Transect_ID, Latitude, Longitude), the
 species and individual (Species, Lemur_ID) and their perpendicular
 distance from the transect in metres (Distance) is provided. The length of
 the transect in metres is provided in the Transect_Length field. The
 "Transects" sheet contains summary information on each transect
 walk , where each row represents a single transect walk. For each walk
 (Transect_Number), information on the transect location (Forest, Fragment,
 Edge_or_Core, Transect, Tranect_ID), its length in metres (Length), the
 date (Date) and the number of each species observed (Mirza_zaza,
 Lepilemur_sahamalaza, Cheirogaleus_medius, Microcebus_sambiranensis) is
 provided. The second sheet, `Transect_Properties`, contains information on
 transect and forest fragment properties. Both raw data sheets enable the
 calculation of the population density values that have been analysed in
 the associated publication. The "Ankarafa Properties" sheet
 contains location (Centre Latitude, Centre Longitude) and size (Total Area
 (Ha), Area of Forest Core (Ha), Forest Core (%)) information on each of
 the 10 forest fragments of Ankarafa. Size information is in hectares. This
 sheet also contains information on transect properties fir the Ankarafa
 fragments (Transect Length (m), Transect Core Length (m), Transect Core
 (%)), where lengths are given in metres. The "Anabohazo
 Properties" sheet provides the same transect information for the
 transects location in the Anabohazo Forest.