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1 July 2006 Factors Affecting the Between-Season Divorce Rate in the Urban Populations of the European Blackbird Turdus merula in North-Western Poland
Dariusz Wysocki
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The between-season divorce rate of the European Blackbird was studied in 1997–2003 in two city parks in northwest Poland. Within the population studied, 52 and 51% of pairs in each park were observed to divorce. Of the eight parameters included in the analysis, the divorce rate was found to depend on marriage training and the time of territory acquisition. Territory quality, breeding success, synchrony in territory acquisition, age and size of the partners were unimportant. 19.5% of pairs with marriage training were observed to divorce, whereas 65.5% of pairs without marriage training did so. Birds acquiring their territories earlier divorced their partners significantly less frequently than those acquiring a territory at a later date. During the first post-divorce breeding season, young males that stayed in the park started breeding earlier than in the preceding year; old males started breeding later, whereas the difference was not significant in young or old females. Regardless of their age, the divorced birds showed a reduced number of fledglings raised with a new partner. The reduced breeding success may be a result of poor adaptation to increased pressure from predators. Similar divorce rates in pairs with and without breeding success and the rarer divorces among pairs claiming their territories earlier strongly support the habitat-mediated hypothesis. However, the more frequent desertion of poor territories by females, as well as differences found between older males and females in the timing of the onset of breeding before and after divorce, indicate that an individual may choose divorce to maximize fitness.



S. Choudhury 1995. Divorce in birds: a review of the hypotheses. Anim. Behav. 50: 413–429. Google Scholar


J. C. Coulson 1972. The significance of the pair-bond in the Kittiwake. Proc. Int. Ornithol. Congr. 25: 424–433. Google Scholar


A. Desrochers 1992. Age-related differences in reproduction by European blackbirds: restraint or constraint. Ecology 73: 1128–1131. Google Scholar


A. Desrochers , R. D. Magrath 1993. Age-specific fecundity in European blackbirds (Turdus merula): Individual and population trends. Auk 110: 255–263. Google Scholar


A. Desrochers , R. D. Magrath 1996. Divorce in the European blackbird: seeking greener pastures. In: J. M. Black (ed.). Partnerships in birds: the study of monogamy. Oxford Univ. Press. Google Scholar


A. A. Dhondt , F. Adriaensen 1994. Causes and effects of divorce in the blue tit Parus caeruleus. J. Anim. Ecol. 63: 979–987. Google Scholar


B. J. Ens , S. Choudhury , J. M. Black 1996. Mate fidelity and divorce in monogamous birds. In: J. M. Black (ed.). Partnerships in birds: the study of monogamy. Oxford Univ. Press. Google Scholar


L. A. Freed 1987. The long-term pair bond of tropical house wrens: advantage or constraint? Am. Nat. 130: 507–525. Google Scholar


D. Heg , L. W. Bruinzeel , B. J. Ens 2003. Fitness consequences of divorce in the oystercatcher, Haematopus ostralegus. Anim. Behav. 66: 175–184. Google Scholar


J. Marchant , R. Hudson , S. P. Carter , P. A. Whittington 1990. Population trends of British breeding birds. BTO, Tring. Google Scholar


J. M. McNamara , P. Forslund 1996. Divorce rates in birds: predictions from an optimization model. Am. Nat. 147: 609–640. Google Scholar


R. Mulsow , L. Tomiałojć 1997. Blackbird. In: W. J. M. Hagemeijer , M. J. Blair (eds). The EBCC Atlas of European Breeding Birds: Their Distribution and Abundance, T & AD Poyser, London, pp. 544–545. Google Scholar


M. Owen , J. M. Black , H. Liber 1988. Pair bond duration and the timing of its formation in barnacle geese. In: M. W. Weller (ed.). Wildfowl in winter. Univ. Minnesota Press. Minneapolis. Google Scholar


I. Rowley 1983. Re-mating in birds. In: P. Bateson (ed.). Mate choice. Cambridge Univ. Press. Google Scholar


B. E. Saether 1990. Age-specific variation in reproductive performance of birds. Curr. Ornithol. 7: 251–283. Google Scholar


D. W. Snow 1988. A study of Blackbirds, 2nd ed. British Museum (Natural History), London. Google Scholar


M. Streif , O. A. E. Rasa 2001. Divorce and its consequences in the Common Blackbird Turdus merula. Ibis 143: 554–560. Google Scholar


L. Svensson 1992. Identification Guide to European Passerines. Stockholm. Google Scholar


L. Tomiałojć 1993. Breeding ecology of the Blackbird Turdus merula studied in the primaeval forest of Białowieża (Poland). Part 1. Breeding numbers, distribution and nest sites. Acta Ornithol. 27: 131–157. Google Scholar


D. Wysocki 2004a. Age structure of urban population of Blackbird (Turdus merula) in Szczecin (NW Poland). Zoologica Poloniae 49: 219–227. Google Scholar


D. Wysocki 2004b. Alternative mating strategies in the urban population of European Blackbird (Turdus merula) in Szczecin (NW Poland). Ardea 92: 103–112. Google Scholar


D. Wysocki 2004c. Nest reusing in Blackbirds — the way for the safe breeding? Acta Ornithol. 39: 164–168. Google Scholar


D. Wysocki 2004d. Within-season divorce rate in urban population of European blackbird Turdus merula. Ardea 92: 219–228. Google Scholar


D. Wysocki 2005a. Does corvid abundance affect the breeding success of urban populations of European Blackbird Turdus merula? In: L. Jerzak , B. P. Kavanagh , P. Tryjanowski (eds). Corvids of Poland. Bogucki Wyd. Nauk. Poznań, pp.181–187. Google Scholar


D. Wysocki 2005b. Nest site selection in the urban population of Blackbird (Turdus merula) in Szczecin (NW Poland). Acta Ornithol. 40: 61–69. Google Scholar


D. Wysocki , J. Adamowicz , R. Kościów , P. Śmietana 2004. Breeding territory in urban population of European blackbird Turdus merula. Ornis Fennica 81: 1–12. Google Scholar


D. Wysocki , K. Walasz 2004. Two Blackbird females sharing the same nest. Acta Ornithol. 39: 47–49. Google Scholar
Dariusz Wysocki "Factors Affecting the Between-Season Divorce Rate in the Urban Populations of the European Blackbird Turdus merula in North-Western Poland," Acta Ornithologica 41(1), 71-78, (1 July 2006).
Received: 1 November 2005; Accepted: 1 May 2006; Published: 1 July 2006

between-season divorce rate
European Blackbird
Turdus merula
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