No abstract

The social organization of a group-living animal is defined by a balance between group dynamic events such as group formation, group dissolution, and dispersal events and group stability in membership and over time. Understanding these processes, which are relevant for questions ranging from disease transmission patterns to the evolution of polygyny, requires long-term monitoring of multiple social units over time. Because all great ape species are long-lived and elusive, the number of studies on these key aspects of social organization are limited, especially for western lowland gorillas (Gorilla gorilla gorilla). In this study, we used non-invasive genetic samples collected within an approximately 100 km area of Loango National Park, Gabon to reconstruct group compositions and changes in composition over more than a decade. We identified 98 gorillas and 11 mixed sex groups sampled during 2014-2017. Using published data from 85 individuals and 12 groups surveyed between 2005 and 2009 at the same locality, we tracked groups and individuals back in time. The identification of 11 silverbacks via parentage analyses and the genetic tracking of 39 individuals across studies allowed us to infer six group formations, five group dissolutions, and 40 dispersal events within 12 years. We also observed four groups persisting across the sampling periods with a maximum inferred existence of nearly 17 years and exhibiting variation in membership stability. Our results highlight the variation in composition and stability among groups of western lowland gorillas and illustrate the power of non-invasive genetic sampling for long-term monitoring.

The hill forests of Karen State, Myanmar, were previously inaccessible to biologists and conservationists for security and political reasons. We have, however, now been able to conduct six surveys across the area, using camera traps, for a total of 9,511 trap-nights, to ascertain the presence of threatened mammal species. We obtained 4,191 records of at least 31 mammal species, including 17 categorized as Near Threatened, Vulnerable or Endangered on the IUCN Red List. Carnivores were especially diverse, with 19 species recorded, indicating a globally significant community, including the tiger Panthera tigris, leopard Panthera pardus and dhole Cuon alpinus. Our methodology was not appropriate for estimating relative abundance or occupancy but the species richness of the mammal community, the number of records and the number of locations where species were detected suggest the area is important for the conservation of a globally threatened mammal community that is in decline across the majority of its range. Despite long-standing conservation efforts undertaken by the Karen people, their forests are threatened by hunting and habitat loss. These threats are likely to be exacerbated as political change brings rapid development. Urgent action is thus needed to assist the Karen people to protect one of South-east Asia's last intact rich and diverse ecosystems.

SummaryThe Maleo Macrocephalon Maleo is a megapode bird endemic to Sulawesi, Indonesia, that lays large eggs at communal nesting grounds in naturally-heated sands or soils. It is classified as ‘Endangered’ and many populations have been extirpated due to overexploitation of eggs and loss of connectivity between forest and nesting grounds. The distribution and status of nesting grounds across Northern and Central Sulawesi are relatively well-established, but almost nothing is known about potential Maleo populations of South-east Sulawesi. In this study we used previously established methods to formally assess the status of three Maleo nesting grounds in Buton, South-east Sulawesi, and interviewed egg collectors at these three sites to determine the trends of populations and threats over time. All nesting grounds were severely threatened and can be expected to be abandoned in the near future due to extensive harvest of eggs and deforestation. Eggs were collected both for the wildlife trade (intensively harvested and sold as luxury items to people from distant cities) and local use (opportunistically harvested and both eaten and sold locally). All egg collectors remarked on an increase in illegal logging around nesting grounds over the previous decade. Though the Maleo’s current situation is dire, previous case studies show that collaborative grassroots initiatives supported by government and NGOs can protect nesting grounds and reverse population declines.

Genetic estimation of population sizes has been critical for monitoring cryptic and rare species; however, population estimates do not inherently reveal the permanence or stability of the population under study. Thus, it is important to monitor not only the number of individuals in a population, but also how they are associated in groups and how those groups are distributed across the landscape. Adding to the challenge of obtaining such information with high precision for endangered and elusive species is the need for long-term collection of such data. In this study we compare sampling approaches and genotype non-invasive genetic samples to estimate the number and distribution of wild western lowland gorillas occupying a ~ 100 km 2 area in Loango National Park, Gabon, for the periods 2005-2007 and 2014-2017. Based on the number of genotyped individuals we inferred a minimum of 83 gorillas during the first and 81 gorillas during the second study period. We also obtained similar capture-recapture population size estimates for the two periods despite variance in social dynamics like group formations, group dissolutions and individual dispersal. We furthermore found area fidelity for two groups that were sampled for 10-12 years, despite variation in group membership. Our results revealed how individual movements link groups in a 'network' and show that western lowland gorilla populations can show a high degree of temporal and geographic stability concurrent with substantial social dynamics.