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1 October 2011 Assessing the Population Performance of the Black Rhinoceros in Kruger National Park
Sam M. Ferreira, Cathy C. Greaver, Mike H. Knight
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Small population sizes provide several challenges to conservation managers seeking to ensure species persistence and illustrating conservation success. Black rhinoceros, Diceros bicornis minor, epitomizes these challenges. During October 2008 we used block surveys, estimates of availability and observer bias to calculate landscape-specific black rhino abundances in the southern parts of Kruger National Park, South Africa. We assigned age and sex to individuals, extracted an age distribution, and estimated survival and fecundity given the population growth derived from historical strip transects. The block counts, corrected for 90.3% availability bias with observers missing 3.8% of those, predicted that 627 (95% CI: 588–666) black rhinos resided in the study area. The population increased at 6.75% per annum, the result of high survival and an estimated inter-calving interval of 2.45 years. Age distributions and population growth predicts that subadult males and females have the lowest annual survival, while dependent calves and adults have the highest annual survival. Precise estimates can be obtained with a 20% study area coverage using block counts. This gives coefficient of variances allowing detection of 5% growth from surveys every two years. Detecting 2% annual decline requires bi-annual surveys for 6 years. Our results illustrate that black rhinos are performing well in Kruger National Park.

Sam M. Ferreira, Cathy C. Greaver, and Mike H. Knight "Assessing the Population Performance of the Black Rhinoceros in Kruger National Park," South African Journal of Wildlife Research 41(2), 192-204, (1 October 2011).
Received: 14 March 2011; Accepted: 1 November 2011; Published: 1 October 2011

age distribution
availability bias
block counts
detecting trends
Diceros bicornis
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