Wattled Crane (Grus carunculatus) research and monitoring in the Okavango Delta, Botswana

The globally threatened Wattled Crane (Grus carunculatus) was studied from 2001 to 2004 in the Okavango Delta, Botswana. Between 2001 and 2003, three aerial surveys covering between 8 123 and 10 677km² were conducted, and the Wattled Crane population estimated to be 1 290 ± 158 based on combined estimates from these surveys. The population estimates were 1 219 ± 343, 1 205 ± 235 and 1 450 ± 273 for 2001, 2002 and 2003, respectively. This shows that the Okavango Delta holds the largest single population of Wattled Cranes in the world, containing over 16% of the global population estimate of <7 700 individuals. The main distribution of Wattled Cranes was the Jao/Boro, Nqoga and Khwai/Muanachira River systems, coinciding with the wettest and most productive parts of the delta. The breeding success, estimated using the proportion of juveniles to adults, was found to be 6.7% during the breeding season of 2003–2004. This estimate is low even though the Okavango Delta is relatively pristine, and is probably an artefact of a stable and large population and a variable environment, coupled with the life-history strategy of the Wattled Crane, a long-lived species.