Tropical forests are threatened worldwide due to deforestation. In South and Southeast Asia, gibbons (Hylobatidae) are important to seed dispersal and forest regeneration. Most gibbons are threatened due to deforestation. We studied the western hoolock gibbon (Hoolock hoolock) in Bangladesh to determine population size and extent of suitable habitat. We used distance sampling to estimate density across 22 sites in northeastern and southeastern Bangladesh. We used Maxent modeling to determine areas of highly suitable habitat throughout Bangladesh. Density was estimated to be 0.39 ± 0.09groups/km², and the total estimated population was 468.96 ± 45.56 individuals in 135.31 ± 2.23 groups. The Maxent model accurately predicted gibbon distribution. Vegetation cover, isothermality, annual precipitation, elevation and mean temperature of the warmest quarter influenced distribution. Two areas in the northeast and two areas in the southeast have high potential for gibbon conservation in Bangladesh. We also found significantly more gibbons in areas that had some level of official protection. Thus, we suggest careful evaluation, comprehensive surveys and restoration of habitats identified as suitable for gibbons. We recommend bringing specific sites in the northeastern and southeastern regions under protection to secure habitat for remaining gibbon populations.

Agricultural expansion has had a detrimental effect on tropical forests and the animal communities that depend on them. Agroforestry systems, however, with their more complex tree and plant communities, have been shown to be important habitats for a range of globally threatened species, including nocturnal animals. Here, we present novel data on the encounter rates of seven species of nocturnal mammals in relation to agroforestry systems within four national parks and associated plantations in Bangladesh to examine if encounter rates were influenced by the human population density, presence of plantations, and human access as represented by a Human Influence Index of anthropogenic disturbance. We walked 70.3 km of transects with only semi-natural forest, 26.9 km of transects with semi-natural forest and gardens, and 21.7 km of transects with semi-natural forest and monocultures over 55 nights from 2017–2019. Of the seven species of nocturnal mammals we detected, all were present in Satachari National Park, whereas six occurred in Lawachara National Park, Rajkandi Forest Range, and Rema-Kalenga Wildlife Sanctuary. Within these national parks, three species (Bengal slow loris, large Indian civet, particolored flying squirrel) were more frequently recorded in areas with human disturbance, especially agroforestry plantations. With declining forest cover in Bangladesh, we highlight here the potential of agroforestry systems as emerging important habitats for these species. We encourage long-term studies of these lesser-studied taxa to understand fully the capacity of agroforestry systems in order to support their long-term conservation.

Accurately estimating population sizes for free-ranging animals through noninvasive methods, such as camera trap images, remains particularly limited by small datasets. To overcome this, we developed a flexible model for estimating upper limit populations and exemplified it by studying a group-living synanthrope, the long-tailed macaque ( Macaca fascicularis ). Habitat preference maps, based on environmental and GPS data, were generated with a maximum entropy model and combined with data obtained from camera traps, line transect distance sampling, and direct sightings to produce an expected number of individuals. The mapping between habitat preference and number of individuals was optimized through a tunable parameter ρ (inquisitiveness) that accounts for repeated observations of individuals. Benchmarking against published data highlights the high accuracy of the model. Overall, this approach combines citizen science with scientific observations and reveals the long-tailed macaque populations to be (up to 80%) smaller than expected. The model’s flexibility makes it suitable for many species, providing a scalable, noninvasive tool for wildlife conservation.

Wildlife trafficking has escalated in recent years, leading to a rise in animal rescues every year. In Bangladesh, increasing numbers of primates are being rescued from illegal trades and private collections. Often, these confiscated individuals are released into the wild without proper assessment and rigorous planning. The survivability of these animals, as well as the potential negative impacts on both the released individual and recipient ecosystems, has not been systematically evaluated. In this study, we document two cases of misguided primate releases outside their natural ranges with potentially significant consequences. At two sites, two released individuals, an Assamese macaque ( Macaca assamensis ) and a capped langur ( Trachypithecus pileatus ), integrated into groups of native primates and engaged in interspecific mating. Community interviews further indicated another improper release of an Assamese macaque at another site. These incidents likely resulted from species misidentification and raise serious concerns regarding mixed‐species associations and potential hybridization between native and non‐native primates. Collectively, our findings underscore the need for rigorous species‐level verification prior to releases, adherence to IUCN translocation guidelines, and development of national protocols to mitigate human‐mediated hybridization risks and to safeguard native biodiversity.