| Publication Type: | Journal Article |
| Year of Publication: | 1989 |
| Authors: | Dunn, PO, Hannon, SJ |
| Journal: | The Auk |
| Volume: | 106 |
| Issue: | 4 |
| Date Published: | 1989 |
| ISBN Number: | 00048038 |
| Keywords: | Corvidae, Pica, Pica hudsonia, Pica pica |
| Abstract: | The hypothesis that an absolute need for male parental care maintains monogamy in bird populations has been rejected in almost all studies where males have been removed. However, most of these studies examined species in which males contributed less parental care than females. In Black-billed Magpies (Pica pica), the sexes have relatively similar levels of parental care. We removed male magpies during the laying period to early in the nestling period and found that 100% of unaided females failed to produce any offspring (n = 20), while 48% of females with mates (n = 106) failed to produce any young. The nest-visit rate of unaided females was lower than that for both the male and female at control nests during the incubation and nestling periods. Unaided females made <50% of the visits of control pairs after hatch, when many (54%) nests of unaided females failed. Male parental care is more important in Black-billed Magpies than in any other passerine in which the need for male parental care has been examined experimentally. This does not necessarily indicate that an absolute need for male parental care maintains monogamy in magpies. It may still be possible for males to produce more offspring by aiding two females, if two females can each produce some offspring with a fraction of the male's total parental care. We argue that this is unlikely because male magpies do not appear to assist more than one mate successfully. We believe that a need for male parental care is the most likely factor maintaining monogamy in this population of Black-billed Magpies. |
| URL: | http://www.jstor.org/stable/4087668 |
| Short Title: | The Auk |
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