First record in over 40 years of the endemic Gerbillus hesperinus in Morocco using thermal imaging and live trapping in collaboration with mammalwatchers

Haytam Iallaten, Demian Hiß, Lorenz Achtnich, Hajar Boufrane, Xabi Clùa, Jeanne Magnin, Claudio S Quilodrán, Rayane Vuillemin, Sandrine Wider, Sidi Imad Cherkaoui, Valentin Moser

The Moroccan Atlantic coast harbors a distinctive but poorly understood mammal fauna, including the endangered endemic gerbil Gerbillus hesperinus, a specialist of coastal sandy habitats not recorded for over 40 years. To assess its persistence, a multi-method survey integrating handheld thermal imaging with recording small mammal tracks and live trapping was conducted over seven nights in March 2026 near Essaouira. Across a sampling effort of 750 live trapping nights and 43.45 km of nocturnal thermal transects, we recorded five G. hesperinus and seven G. campestris. All G. hesperinus records were restricted to sandy, sparsely vegetated coastal dunes near the village of Ouassane. Detection was exceptionally low, potentially indicating a low population density. Morphological examination confirmed hairy foot-soles and revealed a field-identification trait: a grey patch below the eye in G. hesperinus, compared to the entirely white facemask of G. campestris. These findings confirm the persistence of G. hesperinus after more than four decades with no records, while also indicating a low population density in an extremely restricted range highly vulnerable to anthropogenic pressures such as invasive vegetation and recreational development. Consequently, we advocate for immediate conservation measures focused on the remaining dune habitats around Ouassane, as well as a formal reassessment of the species' current IUCN Red List status. More broadly, we showcase the potential of integrating thermal imaging citizen science to locate data-deficient small mammals.