In 1981, after nearly 100 years of absence, the first elephants were reintroduced to the Hluhluwe-iMfolozi region of KwaZulu-Natal, South Africa. Remarkably, all 200 elephants reintroduced over the next 15 years were juveniles (around 2-5 years of age). The new paper by Tim Kuiper, and Dave and Heleen Druce, Demography and social dynamics of an African elephant population 35 years after reintroduction as juveniles, shows how this unusual founder population has grown and thrived over 35 years, now made up of numerous multi-generation family groups typical of more natural elephant populations.
By the end of the 19th century only a handful of elephants remained in South Africa after decades of booming trade in ivory. Around 870 tonnes of ivory left Port Natal (now Durban) between 1845 and 1895 alone, draining the hinterland of pachyderms. Remarkable conservation efforts commenced 100 years later: savannah elephants (mostly juveniles) sourced from a recovering population in Kruger National Park were reintroduced to over 58 protected systems (most <1000km2) across the country. The elephants took very well to their new homes, with their numbers growing at rates far exceeding those of more established elephant populations. Reintroduction success? Yes, and no. The elephant population in Hluhluwe-iMfolozi Park grew from 200 to almost 700 individuals between 1996 and 2016, creating concerns about overpopulation and knock on effects on vegetation and other biodiversity. Along with other reserves in the region, the park is implementing a contraception programme to reduce future growth. A portion of adult females are darted annually with an immune-contraceptive vaccine, administered by a veterinarian from a helicopter. Elephant overpopulation, and population control, are matters of significant debate.
Population concerns aside, another interesting part of the Hluhluwe-iMfolozi elephants’ story, as told in this new paper, is how they have developed a normal social structure from a highly natural baseline of several unrelated cohorts of juvenile elephants introduced over multiple years into different areas of the park, without adults. No adults were introduced to the park until 2000, when 10 adult bulls from Kruger were introduced to dominate younger bulls who, having entered musth early in the absence of adults, had been killing rhinoceros. The society developed from the bottom up; by 1990 the first cohorts had reached sexual maturity with the first calf born in 1990. Since then, these mother-calf units have gradually developed into small families with 3-6 generations of offspring. Today, these semi-independent families remain highly connected in fascinating ways. The typical family joins up temporarily with several additional families at different times, before splitting up again. Just the kind of fission-fusion sociality typical of more established populations.
While not included in the final paper, a social network analysis showed a high level of connectedness among families (see the network diagram below). Many core families are still too young to have become strongly independent. Preferred associations among families were evident, which may be explained by the oldest females of each associating family being closely related, or having been introduced in the same cohort of juveniles.
Read the full article, Demography and social dynamics of an African elephant population 35 years after reintroduction as juveniles in Journal of Applied Ecology.