Co-occurring cryptic species pose challenges for conservation: a case study of the African dwarf crocodile (<i>Osteolaemus</i>spp.) in Cameroon

Abstract

Abstract The conservation status of threatened taxa may be obfuscated by the detection of cryptic species complexes, in both vertebrate and invertebrate species. African dwarf crocodiles ( Osteolaemus spp.) are hunted throughout their range but their conservation status is unknown. Few population assessments have been carried out and there has been a taxonomic revision of the number of species in the genus. The similar morphologies of Osteolaemus tetraspis and Osteolaemus osborni pose a challenge for conservation in Cameroon, where they are still managed as a single species. Nocturnal spotlight surveys were conducted in three regions during August–November 2010 and December 2011–February 2012 to provide population assessments of O. tetraspis and O. osborni and raise awareness of the two species in Cameroon. The mean encounter rates of O. tetraspis and O. osborni were 1.02 ± SD 1.34 (65 individuals in 39 surveys) and 0.61 ± SD 0.38 (three in four surveys) crocodiles per km, respectively. The O. tetraspis population comprised juveniles predominantly and had a male-biased sex ratio. The few O. osborni detected comprised both adults and juveniles. Both species are threatened in Cameroon, based on low encounter rates, young population structures and the threats of habitat loss and hunting pressure. This study provides distribution maps and serves as a baseline to quantify population trends and inform conservation strategies.