No abstract

Immunocontraception has been widely used as a management tool to reduce population growth in captive as well as wild populations of various fauna. We model the use of an individual-based rotational immunocontraception plan on a wild elephant, Loxodonta africana, population and quantify the social and reproductive advantages of this method of implementation using adaptive management. The use of immunocontraception on an individual, rotational basis stretches the inter-calving interval for each individual female elephant to a management-determined interval, preventing exposing females to unlimited long-term immunocontraception use (which may have as yet undocumented negative effects). Such rotational immunocontraception can effectively lower population growth rates, age the population, and alter the age structure. Furthermore, such structured intervention can simulate natural process such as predation or episodic catastrophic events (e.g., drought), which regulates calf recruitment within an abnormally structured population. A rotational immunocontraception plan is a feasible and useful elephant population management tool, especially in a small, enclosed conservation area. Such approaches should be considered for other long-lived, social species in enclosed areas where the long-term consequences of consistent contraception may be unknown.

No abstract

Given their vulnerability to local extinction, the reintroduction of megafauna species (often long‐lived, ecologically influential and highly social) is an increasingly relevant conservation intervention. Studies that evaluate past megafauna reintroductions are both critical and rare. Between 1981 and 1996, 12 cohorts of a total of 200 juvenile (<5 years old) African savannah elephants Loxodonta africana africana were reintroduced to Hluhluwe‐iMfolozi Park (HiP), South Africa, after 100 years of absence. Here, we model the population's long‐term growth. We also present data on the current (2016) age class distribution and social dynamics of the population based on a year of intensive vehicle‐based monitoring of 16 collared adult females and their family groups. Exponential population growth (7.1% annual increase) between 1996 and 2014 suggests reintroduction success but has created concerns about overpopulation (with contraception of females implemented since 2014 to suppress reproduction). The age class distribution has normalized as the juveniles have aged; reproductive females (>10 years old) composed 30% of the population in 2016. The population remains relatively young and forecasts suggest high potential for sustained growth over the next decade. The first calf was born to a reintroduced female in 1990 and since then mother–calf units have gradually developed into semi‐independent multi‐generation families (7–15 individuals in size in 2016). The size of observed cow–calf groups was highly variable (mean = 21.4 individuals, range: 7–109), with repeat observation of individual collared females revealing fusion and fission among different family groups through time, as is typical of more natural elephant populations. Synthesis and applications. From an unusual founder population of reintroduced juvenile elephants, we document rapid population growth and the development of normal sociality over 35 years. While this may be an encouragement for megaherbivore reintroductions in general, the potential for exponential population growth must be carefully considered when ecologically influential species are introduced to closed systems. Our study provides key long‐term insights for elephant translocations, which are becoming increasingly necessary due to overpopulation in some areas and local extinction in others.

Increasing popularity of wildlife viewing has resulted in a rapid increase in small, enclosed reserves in South Africa. The African elephant is one of the many species that has been reintroduced into these reserves for eco-tourism. These elephant populations were established as young (smaller that 10 years old) orphans from prior Kruger National Park culling operations. Consequently, this abnormal sex and age structure of these introduced populations has influenced their behavioural and spatial ecology. In Pilanesberg National Park, this abnormal behaviour was corrected by introducing older bulls and culling certain problem elephants. In July 2003, three older bulls (29–41 years old) were introduced into Phinda Private Game Reserve, KwaZulu-Natal, South Africa in order to normalise the bull age structure. These introduced bulls were monitored intensively after release, as was the resident bull population, both before and after introduction of the older bulls. The introduced bulls settled into restricted ranges separate from the family groups. All the resident bulls decreased their home ranges at first, with most increasing their home ranges a year later. The resident bulls’ change in ranging patterns was due more to ecological factors than to the influence of the mature bull introduction. This study indicates that the introduction of older male elephants into small populations does not pose major risks or animal welfare concerns.