Projected development in Borneo and Sumatra will greatly reduce connectivity for an apex carnivore

The islands of Borneo and Sumatra are strongholds for biodiversity and home for many endemic species. They also have experienced amongst the highest deforestation rates globally. Both islands are undergoing massive, rapid infrastructure development, leading to further deforestation and habitat fragmentation. Here, we identify priority areas for continued functional forest connectivity across Borneo and Sumatra, using spatial models of clouded leopard (Neofelis diardi, a forest indicator species) movement, and impacts thereto from existing and future infrastructure development. We specifically measure and map the anticipated impacts on forest functional connectivity of three major infrastructure development projects (Pan Borneo Highway, Trans-Sumatran Toll Road, and the new Indonesian capital city of Nusantara). We found that core clouded leopard habitats are already highly fragmented in Sumatra, constituting only ∼13 % of the island, with potential dispersal corridors still linking some habitat fragments. In Borneo, clouded leopard core habitats cover 34 % of the island, with one large central core area and several much smaller satellite cores, which are largely unprotected (15 % protected, compared to 42 % in Sumatra). The largest negative effect on habitat connectivity was predicted for Nusantara (66 % of the total connectivity loss predicted for all three infrastructure projects), reverberating across the entirety of Borneo with the strongest effects in East Kalimantan. The Pan Borneo Highway accounted for 28 % of the total connectivity loss, affecting every province in Borneo and Brunei, with 6 % of this decrease located within protected areas. The Trans-Sumatran Toll Road had the smallest negative effect on connectivity (6 %) but only when excluding the already built segments, which, when included, produce a total negative impact similar to that of the Pan Borneo Highway.

Female-biased introductions produce higher predicted population size and genetic diversity in simulations of a small, isolated tiger (Panthera tigris) population

Isolation of wildlife populations represents a key conservation challenge in the twenty-first century. This may necessitate consideration of translocations to ensure population viability. We investigated the potential population and genetic trajectory of a small, isolated tiger (Panthera tigris) population in Thailand's Dong Phayayen-Khao Yai forest complex across a range of scenarios. Using an individual-based, spatially-explicit population modelling approach, we simulate population and genetic trajectories and evaluate the relative impact of translocations from a related population. Population and genetic trajectories in our study were most sensitive to sex and number of individuals translocated and translocation frequency. Translocation of females produced consistently higher population, allelic richness, and heterozygosity compared to equal numbers of males. Despite population increases, declines in allelic richness and heterozygosity across simulations were stark, with simulations predicting a mean decline of allelic richness and heterozygosity of 46.5% and 53.5% without intervention, respectively. Translocations of four females every generation or every other generation were required to prevent substantial heterozygosity declines. While translocations could increase population size, they may fail to prevent long-term loss of genetic diversity in small populations unless applied frequently. This reinforces the importance of incorporating realistic processes of genetic inheritance and gene flow in modelling small populations.

Current trends suggest most Asian countries are unlikely to meet future biodiversity targets on protected areas

Aichi Target 11 committed governments to protect ≥17% of their terrestrial environments by 2020, yet it was rarely achieved, raising questions about the post-2020 Global Biodiversity Framework goal to protect 30% by 2030. Asia is a challenging continent for such targets, combining high biodiversity with dense human populations. Here, we evaluated achievements in Asia against Aichi Target 11. We found that Asia was the most underperforming continent globally, with just 13.2% of terrestrial protected area (PA) coverage, averaging 14.1 ± SE 1.8% per country in 2020. 73.1% of terrestrial ecoregions had <17% representation and only 7% of PAs even had an assessment of management effectiveness. We found that a higher agricultural land in 2015 was associated with lower PA coverage today. Asian countries also showed a remarkably slow average annual pace of 0.4 ± SE 0.1% increase of PA extent. These combined lines of evidence suggest that the ambitious 2030 targets are unlikely to be achieved in Asia unless the PA coverage to increase 2.4-5.9 times faster. We provided three recommendations to support Asian countries to meet their post-2020 biodiversity targets: complete reporting and the wider adoption "other effective area-based conservation measures"; restoring disturbed landscapes; and bolstering transboundary PAs.

Contrasting effects of human settlement on the interaction among sympatric apex carnivores

In the face of a growing human footprint, understanding interactions among threatened large carnivores is fundamental to effectively mitigating anthropogenic threats and managing species. Using data from a large-scale camera trap survey, we investigated the effects of environmental and anthropogenic variables on the interspecific interaction of a carnivore guild comprising of tiger, leopard and dhole in Bhutan. We demonstrate the complex effects of human settlement density on large carnivore interactions. Specifically, we demonstrate that leopard–dhole co-occupancy probability was higher in areas with higher human settlement density. The opposite was true for tiger–leopard co-occupancy probability, but it was positively affected by large prey (gaur) abundance. These findings suggest that multi-carnivore communities across land-use gradients are spatially structured and mediated also by human presence and/or the availability of natural prey. Our findings show that space-use patterns are driven by a combination of the behavioural mechanism of each species and its interactions with competing species. The duality of the effect of settlement density on species interactions suggests that the benefits of exploiting anthropogenic environments are a trade-off between ecological opportunity (food subsidies or easy prey) and the risk of escalating conflict with humans.

Temporal Non-stationarity of Path-Selection Movement Models and Connectivity: An Example of African Elephants in Kruger National Park

Effective conservation and land management require robust understanding of how landscape features spatially and temporally affect population distribution, abundance and connectivity. This is especially important for keystone species known to shape ecosystems, such as the African elephant (Loxodonta africana). This work investigates monthly patterns of elephant movement and connectivity in Kruger National Park (KNP; South Africa), and their temporal relationship with landscape features over a 12-month period associated with the occurrence of a severe drought. Based on elephant locations from GPS collars with a short acquisition interval, we explored the monthly patterns of spatial-autocorrelation of elephant movement using Mantel correlograms, and we developed scale-optimized monthly path-selection movement and resistant kernel connectivity models. Our results showed high variability in patterns of autocorrelation in elephant movements across individuals and months, with a preponderance of directional movement, which we believe is related to drought induced range shifts. We also found high non-stationarity of monthly movement and connectivity models; most models exhibited qualitative similarity in the general nature of the predicted ecological relationships, but large quantitative differences in predicted landscape resistance and connectivity across the year. This suggests high variation in space-utilization and temporal shifts of core habitat areas for elephants in KNP. Even during extreme drought, rainfall itself was not a strong driver of elephant movement; elephant movements, instead, were strongly driven by selection for green vegetation and areas near waterholes and small rivers. Our findings highlight a potentially serious problem in using movement models from a particular temporal snapshot to infer general landscape effects on movement. Conservation and management strategies focusing only on certain areas identified by temporarily idiosyncratic models might not be appropriate or efficient as a guide for allocating scarce resources for management or for understanding general ecological relationships.