Data from: Demography and social dynamics of an African elephant population 35 years after reintroduction as juveniles

1. 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. 2. Between 1981 and 1996, 12 cohorts of a total of 200 juvenile
(<5 years old) African savanna elephants (Loxodonta africana
africana) were re-introduced 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. 3. Exponential population growth (7.1% annual increase)
between 1996 and 2014 suggests reintroduction success but has created
concerns about overpopulation (with contraception implemented since 2014
to suppress reproduction). The age class distribution has normalised 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. 4. 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. 5. Synthesis and
applications: The development of normal elephant demography and sociality
from an irregular founder population may be an encouragement for the
reintroduction of other megaherbivores. The potential for rapid population
growth must however be carefully considered, especially when
ecologically-influential species are introduced to closed systems. The
observed age class distribution and the estimated potential for future
growth over the next decade have implications for the park’s contraception
strategy. Finally, our study provides key long-term insights for elephant
translocations, which are becoming an increasingly common and necessary
management intervention (due to overpopulation in some areas and local
extinction in others).04-Jun-2018