Data from: Good reasons to leave home: proximate dispersal cues in a social spider

Natal dispersal is a successful tactic under a range of conditions in
spite of significant costs. Habitat quality is a frequent proximate cause
of dispersal, and studies have shown that dispersal increases both when
natal habitat quality is good or poor. In social species kin competition,
favoring dispersal, may be balanced by the benefits of group living,
favoring philopatry. We investigated the effect of changes in the local
environment on natal dispersal of adult females in a social spider
species, Stegodyphus dumicola (Araneae, Eresidae), with a flexible
breeding system, where females can breed either within the colony or
individually following dispersal. We manipulated foraging opportunities in
colonies by either removing the capture webs or by adding prey and
recorded the number of dispersing females around each focal colony, and
their survival and reproductive success. We predicted that increasing kin
competition should increase dispersal of less-competitive individuals,
while reducing competition could cause either less dispersal (less
competition) or more dispersal (a cue indicating better chances to
establish a new colony). Dispersal occurred earlier and at a higher rate
in both food-augmented and web-removal colonies than in control colonies.
Fewer dispersing females survived and reproduced in the web-removal group
than in the control or food augmented groups. The results support our
prediction that worsening conditions in web-removal colonies favor
dispersal, whereby increased kin competition and increased energy
expenditure on web renewal cause females to leave the natal colony. By
contrast, prey augmentation may serve as a habitat-quality cue; when the
surrounding habitat is expected to be of high quality, females assess the
potential benefit of establishing a new colony to be greater than the
costs of dispersal.