Browsing by Author "Rasolondraibe, E."
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- Daraina sportive lemur (Lepilemur milanoii) density and population size estimates in most of its distribution range: the Loky-Manambato region.Publication . Salmona, J.; Ralantoharijaona, T.; Thani, I.M.; Rakotonanahary, A.; Zaranaina, R.; Jan, F.; Rasolondraibe, E.; Barnavon, M.; Beck, A.; Wholhauser, S.; Ranirison, P.; Zaonarivelo, J.R.; Rabarivola, C.; Chikhi, L.The population of the Daraina sportive lemur (Lepilemur milanoii) is believed to be mostly confined to the Loky-Manambato region (Louis et al., 2006). Very little is known about L. milanoii and it is classified as “Data Deficient” by the IUCN (IUCN, 2013; Schwitzer et al., 2013). Despite the management of the area by the NGO Fanamby since 2005, no study had been conducted to determine the presence and the abundance of L. milanoii in the main forest fragments of the region. During the 2011 dry season we surveyed the ten main forest fragments of the Loky-Manambato region and estimated L. milanoii densities and population sizes using line transect distance sampling (Buckland, 2001) and the DISTANCE software (Thomas et al., 2010). The results suggest that sportive lemur densities are reasonably high in the region, but with important discrepancies between forest fragments, with densities ranging from 49.8 ind./km² in Antsaharaingy to 590.5 ind./km² in Ampondrabe. For the region Loky-Manambato we were able to estimate a population size of 52,000 individuals. This is the first estimate for the total population size and we argue that similar studies should be repeated to monitor environmental changes and anthropogenic pressures (hunting, deforestation, mining, etc.).
- Estimation des densités et tailles de population du Microcèbe Roux du Nord de (Microcebus tavaratra) dans la région Loky-Manambato (Daraina)Publication . Salmona, J.; Rakotonanahary, A.; Thani, I.M.; Zaranaina, R.; Ralantoharijaona, T.; Jan, F.; Rasolondraibe, E.; Barnavon, M.; Beck, A.; Wholhauser, S.; Ranirison, P.; Zaonarivelo, J.R.; Rabarivola, C.; Chikhi, L.La région Loky-Manambato dans le Nord de Madagascar, est connue pour abriter le propithèque à couronne dorée (Propithecus tattersalli), un lémurien emblématique et endémique de la région. Néanmoins cette région composée d’une dizaine de fragments forestiers de taille moyenne et encore relativement peu étudiés, abrite aussi le microcèbe roux du nord (Microcebus tavaratra). Malgré la gestion des forêts de cette région par l’ONG Fanamby depuis 2005, aucune étude n’avait encore été menée dans chacun des fragments forestiers de la région pour déterminer la présence et quantifier la taille des populations de microcèbes de chacun d’entre eux. Lors de notre étude nous avons tenté d’estimer les densités et les tailles des populations de M. tavaratra dans neuf des dix principaux fragments forestiers de la région. Dans ce but nous avons utilisé la méthode de «line transect distance-sampling». Nos résultats montrent que les densités de microcèbes sont relativement élevées, et varient de 28 à 325 ind/km² entre fragments forestiers de la région. Desétudes plus approfondies des données collectées seront nécessaires pour déterminer les variables environnementales responsables des différences de densité observées.
- Spatial Variation in Density and Total Size Estimates in Fragmented Primate Populations: The Golden-Crowned Sifaka (Propithecus tattersalli)Publication . Quemere, E.; Champeau, J.; Besolo, A.; Rasolondraibe, E.; Rabarivola, C.The golden-crowned sifaka (Propithecus tattersalli) is an endangered lemur species found only in the Daraina region, a very restricted area in north-eastern Madagascar. Its forest habitat is highly fragmented and expected to suffer from significant changes in the near future. The species is poorly known and only one census study, carried out in 2000, has ever been published. It is thus crucial to update the conservation status of the golden-crowned sifaka. before major anthropogenic environmental changes take place. Using the line-transect approach, we estimated the species density in the main forest fragments located in both the peripheral and central parts of the distribution range, including both protected and unprotected areas. In parallel, we tried to determine whether an edge effect could be detected by comparing densities at different distances from the forest edges. We found important variation of sifaka densities among forest fragments. The total species abundance is thus difficult to determine, but we estimated that it is likely to be over 18,000, two to three times higher than previously thought. However, our data also suggested that most P. tattersalli live in forests located in the central part of the distribution range and that the estimated densities in the central part were high (> 80 individuals/km(2)). Two forest fragments, found to host a large part of the total population, are currently outside the managed area and their incorporation to the managed area is strongly recommended. Lastly, as expected for a folivorous and not heavily hunted species, our results are consistent with the hypothesis that this species does not experience a clear edge effect, at least during the first half of the dry season. This could be due to a high resiliency to habitat fragmentation or to the fact that fragmentation has been going on for some time.
- Survey of the critically endangered Perrier’s sifaka (Propithecus Perrieri) across most if its distribution range.Publication . Salmona, J.; Jan, F.; Rasolondraibe, E.; Zaranaina, D.; Ousseni, D.S.; Mohamed-Thani, I.; Rakotonanahary, A.; Ralantoharijaona, T.; Kun-Rodrigues, C.; Carreira, M.; Wohlhauser, S.; Ranirison, P.; Zaonarivelo, J.R.; Rabarivola, C.; Chikhi, L.Propithecus perrieri (Perrier’s sifaka) is one of the most endangered lemur species due to its small and fragmented distribution range. Despite a Critically Endangered (CR) conservation and flagship species status, there are still many uncertainties regarding its actual distribution and its presence in some forests of its putative distribution range. We report the results of diurnal and nocturnal surveys carried out in 2012 across most forest fragments of its putative distribution range, namely the Ankarana National Park, the Analamerana Special Reserve and Andrafiamena-Andava-koera Protected Area. During our surveys the species was only observed in Andrafiamena and Analamerana protected areas.