The data of Woolfenden and Fitzpatrick (1984) show a statistically significant asymmetry in the sex ratio of non-breeders when one of the breeders is not the non-breeder's parent. I propose that the asymmetry is attributable to a combination of two factors acting on non-breeders: the value of inheriting a territory, and incest avoidance. Although natal territories are only occasionally inherited by non-breeders, and then apparently only by males, therate of inheritance is significantly higher for parent/step-parent breeders (n=6) than when both breeders are the non-breeder's parents (n=1). An alternative hypothesis, that stepparents determine the non-breeder asymmetry by ousting potential rivals, might also explain the data, but evidence is currently lacking.
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Brown, J. L. (1987) Book review: Woolfenden, G. E. and Fitzpatrick, J. W. (1984)The Florida Scrub Jay: Demography of a Cooperative-Breeding Bird. Princeton University Press, Princeton, NJ.Auk 104, 350–2.
Woolfenden, G. E. and Fitzpatrick, J. W. (1984)The Florida Scrub Jay: Demography of a Cooperative-Breeding Bird. Princeton University Press, Princeton, NJ, USA.
Woolfenden, G. E. and Fitzpatrick, J. W. (1986) Sexual asymmetries in the life history of the Florida Scrub Jay. InEcological Aspects of Social Evolution: Birds and Mammals. (eds D. I. Rubenstein and R. W. Wrangham) Princeton University Press, Princeton, NJ, USA, pp. 87–107.
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Balcombe, J.P. Non-breeder asymmetry in Florida Scrub Jays. Evol Ecol 3, 77–79 (1989). https://doi.org/10.1007/BF02147933
- Aphelocoma coerulescens coerulescens
- Florida Scrub Jay
- communal breeding