The West African crocodile (Crocodylus suchus) is an emblematic species from the Sahara-Sahel with scarce knowledge on distribution and conservation status. This study updated the knowledge on distribution, occupied habitats, population size, and factors that threaten C. suchus and its habitats in Mauritania. Five field expeditions to Mauritania (2011-2016), allowed the detection of 26 new localities, increasing by 27% the current number of all known locations (adding up to ). In most localities less than five individuals were observed, and in all visiting sites the number of observed individuals ranged from one to 23. Eleven threat factors were identified, being droughts and temperature extremes (100% localities affected) and water abstraction for domestic use and nomadic grazing (94%) the most frequent. These findings suggest that crocodiles are apparently vulnerable in Mauritania and that future local conservation strategies are needed to assure the continuity of its fragile populations and preserve their habitats.

This study provides the first atlas of the distribution of amphibians and reptiles in the Diawling National Park (DNP), Mauritania. Unpublished fieldwork observations collected between 2010 and 2017 were combined with published records and museum data in a geographical information system to produce maps with the distribution of individual species and species richness. The taxonomic list includes 32 species, six amphibians and 26 reptiles, grouped in 17 families. Ten species are new records for the area. Species form distinct groups according to their distribution patterns and preliminary habitat selection trends: 1) species distributed in inland dunes, some extending their range to coastal dunes; 2) species distributed in inland dunes and floodplains; and 3) species associated with habitats that are permanently or seasonally flooded or that inhabit riparian forests. Three areas accumulating most of the species found are located in sand habitats of DNP and peripheral zones. Specific counts of Crocod ylus suchus suggest strong seasonal fluctuations in population size inside DNP, which are likely a consequence of the human-mediated dynamics of water availability in the area.

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