Université P. Sabatier CNRS UMR EDB, Toulouse, France.
Am J Primatol. 2010 Jan;72(1):72-80. doi: 10.1002/ajp.20754.
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.
金冠狐猴（Propithecus tattersalli）是一种濒危的狐猴物种，仅分布在马达加斯加东北部一个非常有限的德拉兰纳地区。其森林栖息地高度破碎，预计在不久的将来会发生重大变化。该物种知之甚少，仅有一项于 2000 年进行的普查研究发表过。因此，在重大人为环境变化发生之前，更新金冠狐猴的保护现状至关重要。我们使用样线法估计了位于分布范围的外围和中心的主要森林片段中的物种密度，包括保护区和非保护区。同时，我们试图通过比较森林边缘不同距离的密度来确定是否存在边缘效应。我们发现狐猴密度在森林片段之间存在重要差异。因此，物种的总丰度难以确定，但我们估计其数量可能超过 18000 只，是先前估计的两到三倍。然而，我们的数据也表明，大多数 P. tattersalli 生活在分布范围中心的森林中，并且中心部分的估计密度较高（>80 只/km²）。两个发现容纳了大部分总种群的森林片段目前位于管理区域之外，强烈建议将其纳入管理区域。最后，正如人们所预期的那样，对于一种以树叶为食且不被大量捕猎的物种，我们的结果与该物种至少在旱季的前半段没有明显的边缘效应的假设一致。这可能是由于对栖息地破碎化具有较高的恢复力，或者是由于破碎化已经持续了一段时间。
