Habitat loss and fragmentation are among the major threats to wildlife populations in tropical forests. Loss of habitat reduces the carrying capacity of the landscape and fragmentation disrupts biological processes and exposes wildlife populations to the effects of small population size, such as reduction of genetic diversity and increased impact of demographic stochasticity. The Critically Endangered Cross River gorilla Gorilla gorilla diehli is threatened in particular by habitat disturbance because its population is small and it lives in an area where high human population density results in intense exploitation of natural resources. We used remotely-sensed data to assess the extent and distribution of gorilla habitat in the Cross River region and delineated potential dispersal corridors. Our analysis revealed > 8,000 km2 of tropical forest in the study region, 2,500 km2 of which is in or adjacent to areas occupied by gorillas. We surveyed 12 areas of forest identified as potential gorilla habitat, 10 of which yielded new records of gorillas. The new records expand the known range of the Cross River gorilla by > 50%, and support genetic analyses that suggest greater connectivity of the population than previously assumed. These findings demonstrate that considerable connected forest habitat remains and that the area could potentially support a much larger gorilla population if anthropogenic pressures such as hunting could be reduced.

The conversion of grasslands for agriculture has triggered a serious decline of the European ground squirrel or souslik Spermophilus citellus, categorized as Vulnerable on the IUCN Red List since 1996. The Jakupica phylogeographic lineage of central Macedonia is the smallest of the three major evolutionary lines of the European souslik. This lineage is an important reservoir of within-species diversity and should be regarded as an independent unit for conservation management purposes. It is endemic to Mount Jakupica, where it lives in mountain pastures at 1,500–2,250 m altitude. The total area occupied by sousliks (884 ha) is fragmented and 94% of individuals occur in four colonies. Densities (0.8–5.5 adults ha−1) are lower than those reported elsewhere for the species, with the total population probably <2,000 adults. One large colony, reportedly of c. 1,000 sousliks, was decimated in 2007 by a catastrophic fire and had still not recovered by 2010. A steady decline in livestock grazing, together with the predicted advance of the tree line as a consequence of climate change, will probably reduce the optimal habitat for the souslik and negatively affect population fitness. Monitoring needs to be implemented, at least for the largest colonies, to provide early warning of any declines.

Awareness of parasite risks in translocations has prompted the development of parasite management protocols, including parasite risk assessment, parasite screening and treatments. However, although the importance of such measures seems obvious it is difficult to know whether the measures taken are effective, especially when working with wild populations. We review current methods in one extensively researched case study, the endemic New Zealand passerine bird, the hihi Notiomystis cincta. Our review is structured around four of the 10 questions proposed by Armstrong & Seddon (Trends in Ecology & Evolution, 2008: 23, 20–25) for reintroduction biology. These four questions can be related directly to parasites and parasite management and we recommend using this framework to help select and justify parasite management. Our retrospective study of recent disease and health screening in hihi reveals only partial overlap with these questions. Current practice does not focus on, or aim to reduce, the uncertainty in most steps of the risk assessment process or on evaluating whether the measures are effective. We encourage targeted parasite management that builds more clearly on available disease risk assessment methodologies and integrates these tools within a complete reintroduction plan.

The crested black macaque Macaca nigra, endemic to Sulawesi, Indonesia, is categorized as Critically Endangered on the IUCN Red List and its population in the Tangkoko Nature Reserve is probably the only viable one within its native range. Earlier studies suggested that this population suffered a decline of 75% during 1978–1994. To evaluate its current status we conducted a line transect survey in the Reserve and assessed effects of ecological and anthropogenic variables on macaque abundance and distribution. We estimated a density of 44.9 individuals km-2 (95% confidence interval, CI, 25.6–78.8) and a total population of 1,951 individuals (CI 1,113–3,421). This estimate of density is 35% lower than that of 68.7 individuals km-2 in 1994. There were moderate to strong correlations between macaque abundance and vegetation structure (basal area and canopy tree density). We observed illegal logging in the area and therefore habitat quality for macaques may be indirectly affected by illegal human activities. If our population estimate is projected linearly M. nigra could become extinct in Tangkoko within 46 years, highlighting the urgent need to improve management of illegal hunting and logging in the Reserve.

Knowledge of both population size and genetic diversity is critical for assessing extinction risk but few studies include concurrent estimates of these two components of population biology. We conducted an investigation of population density and size, and genetic variation and past demographic events, of the Endangered grey-headed lemur Eulemur cinereiceps in south-east Madagascar. We estimated lemur density using line-transect surveys and used satellite imagery to calculate forest fragment area in three localities. We collected tissue samples from 53 individuals and used 26 polymorphic microsatellite loci to obtain measures of population structure (divergence and diversity) across these localities. We tested the probability of past bottleneck events using three models. Contrary to expectation, there were no significant differences in population density across localities. Genetic diversity decreased, but not significantly, with decreasing habitat area and population size. We found a higher likelihood of past bottleneck events in the fragmented coastal populations. The low population size and prior decline in diversity in coastal patches are consistent with their isolation, anthropogenic disturbance, and exposure to cyclone activity. The similarities in the estimates of density between continuous and fragmented sites may indicate recent population growth in the fragments but these populations nevertheless remain at risk from reduced levels of genetic variation. These patterns should be confirmed with more extensive sampling across the limited range of E. cinereiceps.

The Madagascar spider tortoise Pyxis arachnoides is endemic to the coastal dry forests of south-west Madagascar. In recent years its range has been reduced by c. 71%, with the species now confined to eight fragmented populations occupying a total of 2,464 km2. These remaining populations are facing a significant threat of extinction because of habitat destruction and other anthropogenic pressures. We developed methodology for a line transect distance sampling survey and applied it systematically across the species' range. The resulting distance model estimated a mean density of 226.9 tortoises km−2 (95% confidence interval, CI, 168.1–306.3) and a total population of 664,980 (95% CI 492,680–897,550). Fragmentation of the species’ range suggests the current population could be <30% of the historical population. Of the remaining population 73.5% falls within protected areas. However, nine of these 12 protected areas are designated as IUCN category III, V or VI parks, allowing some extractive activities to be undertaken. The most effective strategy for the conservation of P. arachnoides would be to reduce the threats to this species and its habitat, and to develop and expand the current community-based conservation and poverty alleviation programmes in the region.

The historical deforestation of the Upper Brahmaputra Valley in the Indian state of Assam has resulted in the transformation of its once-contiguous lowland rainforests into many isolated forest fragments that are still rich in species, including primates. We report the recent history and current status of six diurnal primates in one large (2,098 ha) and three small (<500 ha) fragments of the Upper Brahmaputra Valley. We censused primates in the small fragments during 2002, 2005, 2009, in the large fragment in 2008, and used other published census data to derive population trends. We also used key informant surveys to obtain historical occurrence data for these populations. Our analyses reveal the recent extinction of some populations and the simultaneous long-term persistence of others in these fragments over 16 years. Most populations appeared to have declined in the small fragments but primate abundance has increased significantly in the largest fragment over the last decade. Addressing the biomass needs of the local human populations, which appears to drive habitat degradation, and better protection of these forests, will be crucial in ensuring the future survival of this diverse and unique primate assemblage in the last rainforest fragments of the human-dominated Upper Brahmaputra Valley.