DOI: 10.5061/dryad.dz08kprzw
title: Staging to join non-kin groups in a classical cooperative breeder, the Florida scrub-jay

description: 1. Why unrelated members form groups in animal societies remains a
 pertinent topic in evolutionary biology because benefits for group members
 often are not obvious. We studied subordinates that disperse to join
 unrelated social groups in the Florida scrub-jay Aphelocoma coerulescens,
 a cooperative breeding species mainly composed of kin-based groups. 2. We
 evaluated potential adaptive benefits of dispersing to become an unrelated
 helper (staging) versus remaining home and dispersing only to pair and
 breed (direct dispersal) to understand why non-kin-based groups form. 3.
 Using 35 years of demographic data, we quantified life history aspects of
 staging individuals and tested associations between social and ecological
 factors on the natal and staging territories. We compared fitness outcomes
 between dispersal strategies by analyzing survival, breeding recruitment,
 and direct reproductive output. We tested for sexual asymmetry potentially
 driven by differences in territory acquisition patterns and female-biased
 dispersal for this species. 4. Of birds that reached one-year-old, 28%
 staged at a non-natal territory before breeding or disappearing. Staging
 dispersers departed at younger ages and moved greater distances than
 direct dispersers. When looking at proximate factors on the natal
 territory associated with staging, males left groups with many same-sex
 helpers, while females often left when their father disappeared. For both
 sexes, staging individuals more likely came from high-quality territories
 and joined groups with fewer same-sex helpers than in their natal group.
 While staging and direct dispersers did not differ in survival or
 likelihood of becoming a breeder, staging males became breeders later and
 had lower lifetime reproductive success than direct dispersers. 5. In
 Florida scrub-jays, staging appears to be an alternative strategy for
 female helpers, but a best-of-a-bad-situation for males. This sexual
 asymmetry is consistent with males having more options than females to
 achieve higher reproductive success by breeding near home. Tradeoffs in
 cost-benefits of departing natal territory and joining unrelated groups as
 a helper seem to best explain alternative dispersal patterns, with optimal
 social queues primarily driving the benefits. This research highlights
 plasticity in dispersal behavior in response to social and environmental
 conditions and offers new perspective in our understanding of
 non-kin-based social groups.
description: We used data collected continuously over 35 years from a
 color-banded population of Florida scrub-jays at Archbold Biological
 Station in central Florida (27.10°N, 81.21°W). As part of this long-term
 research, monthly censuses are conducted to document resident territory,
 group composition, survival, and dispersal. All nests are located each
 year, providing detailed records of reproductive success (Fitzpatrick
 & Bowman, 2016; Woolfenden & Fitzpatrick, 1984). All
 territory boundaries are mapped early in each breeding season, and these
 are overlaid on habitat and fire maps annually available at Archbold
 Biological Station (Abrahamson et al., 1984). Using these data, we
 calculated the amount of oak scrub habitat available and amount of scrub
 habitat that was burned in the past 10 years on the natal territory to
 represent measures of territory quality (Fitzpatrick & Bowman,
 2016; Mumme et al., 2015).
description: Contact corresponding author for R script.