| Publication Type: | Journal Article |
| Year of Publication: | 1996 |
| Authors: | LANGEN, TOMA |
| Journal: | Ibis |
| Volume: | 138 |
| Issue: | 3 |
| Date Published: | 1996 |
| ISBN Number: | 1474-919X |
| Keywords: | bias, Calocitta, Calocitta formosa, Corvidae, Cyanocorax, Cyanocorax formosa, Garrulus, Garrulus glandarius, Pica, Pica pica, Psilorhinus, Psilorhinus formosa |
| Abstract: | Greenwood explained the different sex bias in dispersal of birds (usually female biased) and mammals (usually male biased) by a difference in mating systems: male birds primarily defend resources while male mammals primarily defend females. The White-throated Magpie-jay Calocitta formosa is unusual among birds in that females are philopatric and jointly defend permanent resource territories while males disperse before they are 2 years of age. One female in a group is the primary breeder. One male joins the group permanently as her mate. Males that do not have a permanent breeding position circulate among groups and attempt to mate with both the primary breeding female and other group females. Other females feed the primary breeder and her offspring and also pursue other reproductive behaviour, including secondary nesting in the territory and egg dumping into the primary breeder's nest. I argue that the unusual dispersal pattern in this species is a result of the alternative reproductive strategies that can be pursued by males and females excluded from being primary breeders. The White-throated Magpie-jay conforms to Greenwood's predictions: males pursue a mate defence rather than resource defence mating system and they are the dispersing sex. The primary factor influencing alternative reproductive tactics may be asynchronous reproduction among groups during the long breeding season arising from frequent renesting in an area of high nest predation. |
| URL: | http://dx.doi.org/10.1111/j.1474-919X.1996.tb08071.x |
| Short Title: | Ibis |
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