Data from: When to stay and when to leave? Proximate causes of dispersal in an endangered social carnivore

1. Reliable estimates of birth, death, emigration, and immigration rates
are fundamental to understanding and predicting the dynamics of wild
populations and, consequently, inform appropriate management actions.
However, when individuals disappear from a focal population, inference on
their fate is often challenging. 2. Here we used 30 years of
individual-based mark-recapture data from a population of free-ranging
African wild dogs (Lycaon pictus) in Botswana and a suite of individual,
social, and environmental predictors to investigate factors affecting the
decision to emigrate from the pack. We subsequently used this information
to assign an emigration probability to those individuals that were no
longer sighted within their pack (i.e. missing individuals). 3. Natal
dispersal (i.e. emigration from the natal pack) showed seasonal patterns
with female dispersal peaking prior to the mating season and male
dispersal peaking at the beginning of the wet season. For both sexes,
natal dispersal rate increased in the absence of unrelated individuals of
the opposite sex in the pack. Male natal dispersal decreased with
increasing number of pups in the pack and increased in larger packs.
Female natal dispersal decreased with increasing number of pups in larger
packs, but increased with increasing number of pups in smaller packs.
Individuals of both sexes were less likely to exhibit secondary dispersal
(i.e. emigration from a pack other than the natal pack) if they were
dominant and if many pups were present in the pack. 4. Our models
predicted that 18% and 25% of missing females and males, respectively, had
likely dispersed from the natal pack, rather than having died. A
misclassification of this order of magnitude between dispersal and
mortality can have far-reaching consequences in the evaluation and
prediction of population dynamics and persistence, and potentially mislead
conservation actions. 5. Our study showed that the decision to disperse is
context-dependent and that the effect of individual, social, and
environmental predictors differs between males and females and between
natal and secondary dispersal related to different direct and indirect
fitness consequences. Furthermore, we demonstrated how a thorough
understanding of the proximate causes of dispersal can be used to assign a
dispersal probability to missing individuals. Knowledge of causes of
dispersal can then be used within an integrated framework to more reliably
estimate mortality rates.