A model for the noninvasive, habitat-inclusive estimation of upper limit abundance for synanthropes, exemplified by M. fascicularis.

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.

Conservation genomics in the fight to help the recovery of the critically endangered Siamese crocodile Crocodylus siamensis.

Endangered species are often characterized by low genetic diversity and it is imperative for conservation efforts to incorporate the knowledge obtained from genetic studies for effective management. However, despite the promise of technological advances in sequencing, application of genome-wide data to endangered populations remains uncommon. In the present study we pursued a holistic conservation-genomic approach to inform a field-based management programme of a Critically Endangered species, the Siamese crocodile Crocodylus siamensis. Using thousands of single nucleotide polymorphisms from throughout the genome, we revealed signals of introgression from two other crocodile species within our sample of both wild and captive-bred Siamese crocodiles from Cambodia. Our genetic screening of the Siamese crocodiles resulted in the subsequent re-introduction of 12 individuals into the wild as well as the selection of four individuals for captive breeding programmes. Comparison of intraspecific genetic diversity revealed an alarmingly low contemporary effective population size in the wild (<50) with evidence of a recent bottleneck around Tonle Sap Lake. We also projected a probable future extinction in the wild (within fewer than five generations) in this population in the absence of re-introduction efforts. However, an increase in the number of potential breeders through re-introductions, including the one resulting from this project, could counter this trend. Our results have been implemented in ongoing re-introduction and captive breeding programmes, with major implications for the conservation management of Siamese crocodiles, and provide a blueprint for the rescue effort of other "terminally ill" populations of critically endangered species.

Social and personal information use by squirrel monkeys in assessing predation risk.

The threat of predation can significantly influence prey behaviors through altered perceptions of risk. Prey risk perception is constantly updated via collection of personal and social information about predators. Better understanding of the links between information availability, its use, and prey species' perception of risk will aid in explaining how animals adapt to predation. The goal of this study was to determine the environmental and social cues-available to prey via personal and social information, respectively-that influence wild squirrel monkey (Saimiri sciureus) reactivity to potential predators, treated here as a proxy for risk perception. We followed squirrel monkey troops for 3 years in Suriname, South America, and accounted for environmental and social variables associated with potential predator encounters. We utilized logistic regression models applied to a robust and long-term data set to reveal relationships among factors affecting squirrel monkey anti-predator responses. Our analyses revealed that height, season, type of predator stimulus, and mixed-species associations with capuchin monkeys (Sapajus apella) were highly related to intensity of squirrel monkey anti-predator responses. Moreover, our analyses revealed that squirrel monkeys overestimate the immediate threat of predation when individuals have incomplete information regarding the potential predator.