Circadian rhythms are a mechanism by which species adapt to environmental variability and fundamental to understanding species behavior. However, we lack data and a standardized framework to accurately assess and compare temporal activity for species during rapid ecological change. Through a global network representing 38 countries, we leveraged 8.9 million mammalian observations to create a library of 14,587 standardized diel activity estimates for 445 species. We found that less than half the species’ estimates were in agreement with diel classifications from the reference literature and that species commonly used more than one diel classification. Species diel activity was highly plastic when exposed to anthropogenic change. Furthermore, body size and distributional extent were strongly associated with whether a species is diurnal or nocturnal. Our findings provide essential knowledge of species behavior in an era of rapid global change and suggest the need for a new, quantitative framework that defines diel activity logically and consistently while capturing species plasticity.

This study is the first step towards more systematic monitoring of urban bat fauna in Vietnam and other Southeast Asian countries by collecting bat echolocation call parameters in Ho Chi Minh and Tra Vinh cities. We captured urban bats and then recorded echolocation calls after releasing in a tent. Additional bat’s echolocation calls from the free-flying bats were recorded at the site where we captured bat. We used the obtained echolocation call parameters for a discriminant function analysis to test the accuracy of classifying these species based on their echolocation call parameters. Data from this pilot work revealed a low level of diversity for the studied bat assemblages. Additionally, the discriminant function analysis successfully classified bats to four bat species with an accuracy of >87.4%. On average, species assignments were correct for all calls from Taphozous melanopogon (100% success rate), for 70% of calls from Pipistrellus javanicus, for 80.8% of calls from Myotis hasseltii and 67.3% of calls from Scotophilus kuhlii. Our study comprises the first quantitative description of echolocation call parameters for urban bats of Vietnam. The success in classifying urban bats based on their echolocation call parameters provides a promising baseline for monitoring the effect of urbanization on bat assemblages in Vietnam and potentially also other Southeast Asian countries.

Tropical biodiversity is threatened globally by anthropogenic disturbances, particularly forest degradation and overhunting. Where large mammals have been extirpated, smaller bodied “mesomammals” may play an important ecological role (e.g., as seed dispersers). However, these species are disproportionally affected by overhunting for wildlife trade markets and are routinely understudied as they tend to be rare, cryptic, and nocturnal. Few studies have examined spatiotemporal responses to anthropogenic disturbance by mesomammals at the community level, which may identify imbalances within an ecosystem that could threaten species persistence. We deployed camera traps throughout Cat Tien National Park (i.e., Nam Cat Tien area), southern Vietnam, to (1) identify long‐term changes in terrestrial mesomammal richness and (2) evaluate the effects of forest structure and anthropogenic disturbance on an 18‐species mesomammal community within a historically disturbed tropical forest using hierarchical Bayesian community occupancy models. We found that site occupancy was driven by the interaction between distance to seasonally inundated grassland and absolute forest cover (basal area per hectare). This may be due to the combination of intact forest benefits (refuge from predators and hunters, denning sites) and early successional grassland resources (forage quality), as well as high levels of tolerance for disturbed forest among the largely generalist mesomammal community of Nam Cat Tien. We found no negative effects of current anthropogenic factors at the community level. However, we did find that four disturbance‐tolerant small carnivores have been extirpated since the 1990s and continued human presence in the park suggests that hunting and snaring remain an acute threat to native mesomammals. Without continued efforts to address the unsustainable harvest of wildlife, Southeast Asian's remaining mesomammals are at risk of extirpation despite resilience to moderate levels of disturbance.

The Annamite striped rabbit ( Nesolagus timminsi ) is a forest‐dwelling lagomorph endemic to the Annamite Mountains of Vietnam and Laos. Herein, we report the first detailed observations of its burrowing and reproductive behavior from information gathered via camera traps. From May to October 2024, six camera traps were deployed at suspected burrow sites identified through semi‐structured interviews and field surveys. The active burrows were recorded at multiple sites within broadleaf wet evergreen forests between 359 m and 775 m asl. The camera traps were active for 864 camera trap nights, recording 1293 videos of the species. The videos showed first observations of the Annamite striped rabbit performing a sequence of burrow opening, closing and concealment, including placing compacted soil and small rocks over the entrance. Furthermore, a single behavioral event lasting 190 min was recorded and interpreted as being suggestive of parturition. Forty‐six days after this event, the female was recorded leaving the burrow accompanied by two juveniles. These findings represent the first documentation of such behavior in the species. Our results provide new behavioral information on this little known and endangered animal.

The Annamite Mountains of Indochina have high mammal endemism but also face a mammalian extinction crisis, primarily from the indiscriminate use of snares. Chu Yang Sin National Park in the southern Annamites of Vietnam is one of the few forests in Vietnam where the Critically Endangered Annamite endemic Large-antlered Muntjac is predicted to be present. The objectives of this study were to experimentally investigate and quantify the relative impact of snaring on local mammal populations by using camera trapping, with a focus on muntjac, and to provide a checklist of the large mammal species of the park. In 2020, a preliminary survey was executed to determine a study site in the park by observing the prevalence of signs indicative of large mammals. From December 2020 to February 2021, a 515-m long simulated continuous snare-line was constructed at the study site by five experienced local hunters. Camera-traps were then set up along 240-m of the snare-line to monitor animal movement. A total of 4,747 working camera-trap nights were logged and recorded the Large-antlered Muntjac and 10 other large mammal species along the snare-line. It was found that the Large-antlered Muntjac was more vulnerable to snares relative to the other mammals detected, exhibiting the highest probability of being ‘captured’ by a snare if an individual animal encountered the snare-line (p = 0.67). The finding suggests, as already theorized, that prolonged exposure to a snare-line will greatly reduce local large mammal populations, because with repeated encounters by an individual animal, the probability of capture increases close to p = 1. The study demonstrates here for the first time how some species are potentially more susceptible to snaring than others. Building on the experimental approach, future research could yield new insights into managing snare hunting more efficiently, using more data from other locations and over longer periods.