Brown hyaena population explosion: rapid population growth in a small, fenced system

Context In the past 200 years, many carnivores have experienced a widespread decline in numbers and range reductions. Conservation interventions include the use of small, fenced reserves that have potential restoration benefits for conservation. Over the past 25 years, the Eastern Cape province of South Africa has seen the establishment of many small (≤440 km2) game reserves, and the reintroduction of the larger, indigenous wildlife that had been extirpated by the early 20th century, including brown hyaenas (Hyaena brunnea). These game reserves have restored the environment to a more natural state but little information exists concerning the benefits and implications of introducing elusive animals that are seldom seen after reintroduction. Fenced reserves have the potential to provide surplus animals that can be relocated for restoration purposes (where applicable) or serve as a buffer to the extinction of naturally occurring populations, but careful management is required to monitor populations appropriately, so as to avoid the costs of rapid population increase. Aims The reintroduction of brown hyaenas to the Eastern Cape has provided a case study to assess the role of small reserves and their potential to contribute to conservation, by determining the persistence and population growth of brown hyaenas in a small, enclosed reserve. Methods Estimates of brown hyaena density were calculated using a capture–recapture approach from individually identifiable images captured during a 3-month camera trapping survey. Key results After a single decade, the brown hyaena population increased by at least 367%, from six individuals to a minimum of 28 individuals. These results suggest that this brown hyaena population has the highest density ever recorded for the species in southern Africa. Conclusions and Implications Because brown hyaena populations were high relative to natural unfenced populations, high fences may provide two utilities for their conservation. Fenced reserves may provide surplus animals to support reintroductions and provide protected populations to buffer the risk of species extinction.