A model for the noninvasive, habitat-inclusive estimation of upper limit abundance for synanthropes, exemplified by M. fascicularis .
André L Koch ListonXueying ZhuVan Bang TranPhaivanh PhiapalathSeiha HunTanvir AhmedSabit HasanSajib BiswasShimul NathToufique AhmedKurnia IlhamNgwe LwinJackson L FrechetteNaven HonCain AggerSuzuki AiEmeline AudaEva GazagneJan F KamlerMilou GroenenbergSarah Banet-EugeneNeil ChallisNeth VibolNicole LerouxPablo SinovasSophatt ReaksmeyVanessa H MuñozSusan LappanZaki ZainolValeria AlbaneseAthanasia AlexiadouDaniel R K NielsenAnna HolznerNadine RuppertElodie Floriane BrieferAgustín FuentesMalene Friis HansenPublished in: Science advances (2024)
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.