Distribution and status of crocodylus suchus in and around Kidepo Valley National Park, North-Eastern Uganda

Abstract

Previous and recent research carried out in Uganda’s National Parks focused mainly on large mammals and birds with little research directed towards reptiles and amphibians. A new species of crocodiles, Crocodylus suchus, was recorded in Kidepo Valley National Park in 2011 raising the total number of crocodiles species ever recorded in Uganda. Only Crocodylus niloticus has been widely known in Uganda but as a result of a 2009 crocodile survey in Kidepo, Crocodylus suchus has also been confirmed present. While C.niloticus is categorized as Low Risk on the IUCN Red Lit 2011, C.suchus is uncategorized mainly due to lack of information on its distribution and survival. The distribution and population status of the crocodiles in Kidepo Valley National Park was studied by searching watercourses that formed the line transect walked. Habitat information was recorded including presence or absence of water, river substrate, river bank characteristics and any observable threats. Population structure was studied by capturing, measuring, weighing and identification of sex for individual crocodiles recorded. Distribution and abundance data were analyzed using occupancy Binomial Mixture models performed in PRESENCE software to estimate the relative abundance of crocodiles in and around KVNP. There are approximately 67 to 142 crocodiles in KVNP of which 70% in the Narus valley, 23% in Kidepo valley and 7% outside of the park. Majority (90%) of the crocodiles recorded were adults, and 80% of the captured crocodiles were females. Habitat characteristics had an influence on the distribution, abundance and size of the crocodiles whereby river-streams with sandy beaches were associated with the highest number of mature crocodiles, and pools of water with submerged vegetation associated with the yearlings recorded. No anthropogenic threats towards crocodiles were recorded. The results of this research are in agreement with earlier studies that noted the total abundance of crocodiles in KVNP to be between 100-150 crocodiles with 80% crocodiles in Narus and 20% in Kidepo Valley. It also agrees with earlier research on crocodilians which showed that younger crocodiles are more likely to inhabit slow moving streams or ponds with submerged plants whereas older ones prefer clear faster moving waters. Crocodiles in KVNP were observed to dig, burrow and aestivate in mud caves during the dry season, a behavior that has been reported of other C.suchus in Mauritania. In conclusion, the crocodiles in KVNP were noted to occur mainly in Narus Valley in river streams and pools of water with submerged vegetation. The results of this study will highlight the role of this aquatic top predator in their natural habitat. Results will also be used to plan species-specific conservation and management plans.