Conservation ecology and social behaviour of southern white rhinoceros (Ceratotherium simum simum)

Scott, Sarah (2020) Conservation ecology and social behaviour of southern white rhinoceros (Ceratotherium simum simum). Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Southern white rhinoceros, Ceratotherium simum simum, have extremely low reproductive output in captivity, and there is substantial variation in reproductive success between certain wild populations. To investigate whether social and ecological factors influence female reproduction, this study used data collected from four white rhinoceros populations in Kenya, alongside demographic studbook data from the European captive population. Using population viability analysis, I show that the European captive population is projected to decline 2% annually under current demographic parameters. The proportion of females calving annually (10%) is the main factor limiting population growth, which must increase to 17% to prevent further population decline. Additionally, high infant mortality rates and severe reproductive skew are also of concern. Mean group age, group size and the presence of another breeding female were key factors mediating female breeding behaviour and reproductive success, and thus inadequate social conditions may contribute towards low female reproductive output in captivity. Using social network analysis, I demonstrate that wild white rhinoceros display age-specific association patterns and a strong tendency to form cliques. Individuals often formed longlasting associations, persisting for at least seven months, and social connectivity related to female reproductive success. Grouping patterns varied between populations, most likely due to differences in population density and habitat. Vegetation assessments conveyed that high grass cover, both shorter grass and trees, and low elevation were key features of white rhinoceros habitat across populations. Differences in habitat quality and grazing pressure between populations had little impact on breeding performance, but did influence individual core range size, which increased as population density decreased. The results from this work provide important new insights on white rhinoceros social behaviour and ecology that can be used to inform their conservation management, such as translocations and estimates of ecological carrying capacity in the wild, and group compositions likely to improve female reproductive output in captivity.