Dynamics of an expanding black rhinoceros (Diceros bicornis minor) population

• Published in: European journal of wildlife research Vol. 61; no. 4; pp. 601 - 609
• Main Authors: Law, Peter R., Fike, Brad, Lent, Peter C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2015; Springer Nature B.V
• Subjects: Animal populations; Biomedical and Life Sciences; Density dependence; Diceros bicornis; Ecology; Endangered & extinct species; Endangered species; Fish & Wildlife Biology & Management; Herbivores; Life Sciences; Mammals; Metapopulations; Original Paper; Population dynamics; Population growth; Population number; Reintroduction; Wildlife conservation; Zoology; Density dependence; Population dynamics; Megaherbivores; Stochasticity; Black rhinoceros; Transient dynamics
• ISSN: 1612-4642; 1439-0574
• DOI: 10.1007/s10344-015-0935-3

Understanding population dynamics is critical for meta-population management, especially of endangered species, and also for megaherbivore ecology. We employed complete individual life records to construct census data for a reintroduced black rhinoceros population over 22 years since its founding and investigated its dynamics. Akaike’s information criterion applied to scalar models of population growth based on the generalized logistic unambiguously selected an exponential growth model ( r  = 0.102 ± 0.017), indicating a highly successful reintroduction. No evidence of density dependence was detected, and thus, we could not confirm the threshold model of density dependence that has influenced black rhinoceros meta-population management. Our analysis supported previous work contending that the generalized logistic is unreliable when fitted to data that do not sample the entire range of population sizes. A stage-based matrix model of the exponential population dynamics exhibited mild transient behaviour. We found no evidence of environmental stochasticity, consistent with our previous studies of this population that found no influence of rainfall on demographic parameters. Demographic stochasticity was present, principally reflected in annual sex-specific recruitment numbers that differed from deterministic predictions of the matrix model. Demographically driven process noise should be assumed to be a component of megaherbivore population dynamics, as these populations are typically relatively small, and should be accounted for in managed removals and introductions. Increase in age at first reproduction with increasing population size, as manifested in the study population, may provide a warning of possible density feedback prior to detectable slowing of population growth rate for megaherbivores.