Large body size is an important determinant of individual fitness in many animal species, especially in island systems where habitat saturation may result in strong intraspecific competition for mates and breeding territories. Here we show that large body size is associated with benefits to yearling breeding and extra-pair mating in the Island Scrub-Jay (Aphelocoma insularis), endemic to Santa Cruz Island, California. This species is ~20% larger than its mainland congener, consistent with the island syndrome, indicating that body size may be a trait under selection. From 2009 to 2013, we quantified the reproductive success of a marked population of Island Scrub-Jays, tracked which yearlings acquired a breeding territory and bred, and measured the occurrence of extra-pair paternity. Two potential contributors to fitness were positively related to body size. Larger yearling males were more likely to breed, possibly due to greater behavioral dominance during aggressive encounters. Larger males were also less likely to lose paternity to extra-pair males and, anecdotally, extra-pair males were larger than the social male cuckolded. This study provides evidence that larger males may have a fitness advantage over smaller males by breeding earlier and avoiding paternity loss, but estimates of lifetime reproductive success are ultimately needed for Island Scrub-Jays and other long-lived species.
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Effects of experimental light at night on extra‐pair paternity in a songbird
Light pollution is increasing worldwide and significantly affects animal behavior. In birds, these effects include advancement of morning activity and onset of dawn song, which may affect extra‐pair paternity. Advanced dawn song of males may stimulate females to engage in extra‐pair copulations, and the earlier activity onset may affect the males’ mate guarding behavior. Earlier work showed an effect of light at night on extra‐pair behavior, but this was in an area with other anthropogenic disturbances. Here, we present a two‐year experimental study on effects of light at night on extra‐pair paternity of great tits (
- NSF-PAR ID:
- 10062006
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
- Volume:
- 329
- Issue:
- 8-9
- ISSN:
- 2471-5638
- Page Range / eLocation ID:
- p. 441-448
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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