Factors Affecting the Between-Season Divorce Rate in the Urban Populations of the European Blackbird<i>Turdus merula</i>in North-Western Poland

Wysocki, Dariusz

doi:10.3161/068.041.0101

Cited by 22 publications

(17 citation statements)

References 10 publications

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“…Whether and how sex differences can be detected depends on the mating structure and the degree of age‐assortativeness of matings (Desrochers & Magrath , Auld & Charmantier ). At our study site, we found that about 52% of pairs divorced between seasons (Wysocki ) and 13% changed mates within seasons (Streif & Rasa , Wysocki ), so we expected to recover differences in age‐related changes between the sexes.…”

Section: Methodsmentioning

confidence: 88%

“…). Divorce and mate preferences . Breeding experience, strongly associated with age, has an impact on the between‐season divorce rate: pairs without such experience divorced more often, and after divorce the breeding success of both partners was reduced (Wysocki ). In the case of within‐season divorce, a new partner was always older than or of the same age as the previous one.…”

Section: Discussionmentioning

confidence: 99%

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Age‐specific reproduction and disposable soma in an urban population of Common BlackbirdsTurdus merula

Jankowiak

Zyskowski

Wysocki

2017

Ibis

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The mechanism of senescence is an important subject of current research, but our knowledge of the factors influencing the rate of ageing in naturally occurring populations remains rudimentary. Evolutionary theories of senescence predict that investment in reproduction in early life should come at the cost of reduced somatic maintenance and thus result in earlier or more rapid senescence. We use data on the complete reproductive histories of 431 Common Blackbirds (222 males and 209 females) collected during a 19‐year study of the ecology of an urban population of this species to test the main hypotheses addressing the issue of senescence. On average, the birds in this population survived for 3.7 (± 1.9 sd) years. Reproductive success in females peaked at the age of 4, but in males remained stable until the 5th year of life. We observed declines in reproductive success, indicative of senescence, after the peak years in both sexes. The mechanism of age‐related changes in the reproduction of females confirms the individual improvement and selective disappearance hypotheses. In the case of males, the increase in reproductive performance comes as a consequence of the disappearance of poor reproducers. The parental investment associated with early life fecundity (the first two breeding seasons in males and females) impairs the breeding success of females later on. Contrary to expectations, there was no negative impact of high early life fecundity on either mortality or lifespan. Individuals of both sexes with a high early life fecundity had a higher lifetime reproductive success than those in which early life fecundity was low. Hence, the most profitable strategy is to maximize reproductive effort in the early stages of life. This yields the highest lifetime reproductive success, despite the increased impact of senescence, especially in females. These results are consistent with the disposable soma hypothesis.

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Section: Methodsmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Age‐specific reproduction and disposable soma in an urban population of Common BlackbirdsTurdus merula

Jankowiak

Zyskowski

Wysocki

2017

Ibis

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“…The better-option hypothesis (Choudhury 1995) states that one partner will benefit from divorce, while the abandoned partner is the 'loser': breeding success during the next breeding attempt of the partner initiating divorce should thus be higher than that of the 'loser' partner. Divorces depend on the duration of the pair bond and the higher rate of desertion of females from poor territories; this has been confirmed within seasons (Wysocki 2004b) and between seasons (Wysocki 2006). If this is the case, we cannot rule out the possibility that the abandoned partner was in worse condition, and we may be confusing cause with effect.…”

Section: Within-season Between-state Transitionmentioning

confidence: 97%

“…3) Faithful birds can start breeding earlier, so they can choose the best territory without getting involved in exhausting fights with other males, and courtship, mating and nest building will all be faster. Faithful birds take possession of their territories 25-30 d earlier , Wysocki 2006, which could be especially important in view of the shortage of nest sites in the study area Walasz 2004, Wysocki 2005). As they can start their breeding season earlier, their chances of breeding success are very much improved (Baran andAdkins-Regan 2014, Jankowiak and.…”

Section: Within-season Between-state Transitionmentioning

confidence: 99%

Survival costs of within‐ and between‐season mate change in the European blackbirdTurdus merula

Jankowiak

Cholewa

Wysocki

2018

Journal of Avian Biology

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Many studies of socially monogamous birds discuss the adaptive role of between‐season partner change, but only a handful of them refer to the benefits of pair fidelity in terms of increased survival. Moreover, there are no studies describing the benefits of within‐season mate retention. Our data relating to an urban population of European blackbirds Turdus merula enabled us to test the dependence of survival on pair faithfulness. Because blackbirds divorce within and between seasons, we were able to test the influence of pair faithfulness on their within‐ and between‐season survival and mate fidelity. For this purpose, we used a multievent capture–mark–recapture (MECMR) statistical model, which is based on recapture rates and different pair states (faithful to mate, paired with new partner, or dead). Our study indicated that between‐ and within‐season survival depends on pair states: pair‐bond duration increases survival to the next capture occasion in both sexes. We found that the pair‐bond duration to the current partner increased the chances of being with the same partner during the next breeding occasion, although we failed to find any within‐season pair‐bond influence for females. Our results showed sex differences in mating at the end of the season: females had a much smaller chance of breeding with the current new partner in the next year. This study has demonstrated that within‐ and between‐season survival is dependent on mate retention, and we discuss this in the context of how searching for a new partner could affect the birds’ survival.

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“…If divorce represents a form of adaptive mate choice, it should be triggered either by low breeding success (Dubois & Cézilly, 2002) or by the potential to improve breeding success with a new partner (Choudhury, 1995;Black, 1996), or both. Handel & Gill, 2000;Pampus, Schmidt & Wiltschko, 2005;Wysocki, 2006) to those finding positive effects (e.g. By contrast, if divorce happens by chance, by usurpation, or as a non-selected effect of some other process, it should not correlate with breeding success in the season before, and should lead either to a decrease or to no change in overall breeding success.…”

Section: Introductionmentioning

confidence: 99%

Trading up: the fitness consequences of divorce in monogamous birds

2014

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Social and genetic mating systems play an important role in natural and sexual selection, as well as in the dynamics of populations. In socially monogamous species different genetic mating patterns appear when individuals mate outside the breeding pair within a breeding season (extra-pair mating) or when they change partners between two breeding seasons (widowing or divorce). Divorce can be defined as having occurred when two previously paired individuals are alive during the next breeding season and at least one of them has re-mated with a new partner. In socially monogamous birds divorce is widespread, but it is not clear whether it is a behavioural adaptation to improve the quality of a mating decision or whether, alternatively, it results as a non-selected consequence of other processes: existing studies suggest a heterogeneous set of results with respect to this central question. This heterogeneity could result from a number of factors, ranging from the methodological approaches used, to population- or species-specific characters. In this review we use phylogenetic meta-analyses to assess the evidence that divorce is adaptive (in terms of breeding success) across 64 species of socially monogamous birds. Second, we explore biological and methodological reasons for the heterogeneity in the results of previous studies. Results of our analyses supported the hypothesis that divorce is, in general, an adaptive behavioural strategy as: (1) divorce is triggered by relatively low breeding success; (2) there is a positive change in breeding success as a result of divorce. More specifically, while controlling for methodological moderators, we show that: (i) earlier stages of breeding are better predictors of divorce than later stages (r = 0.231; 95% CI: 0.061-0.391 for clutch size; similar for laying date); (ii) females benefited from divorce more than males in terms of increasing breeding success between successive breeding attempts, with different stages of the breeding cycle improving at different rates (e.g. r = 0.637; 95% CI: 0.328-0.817 for brood-level measures). We show that the effect size was dependent on the methodological approach used across studies and argue that research on the adaptive nature of divorce should be cautious when designing the study and interpreting the results. Altogether, by providing strong evidence that divorce is an adaptive strategy across monogamous birds, the results of our analysis provide a firm ground for further exploration of external covariates of divorce (e.g. demographic factors) and the mechanisms underlying the differences in the effect sizes of the proximal fitness causes and consequences of divorce.

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Factors Affecting the Between-Season Divorce Rate in the Urban Populations of the European BlackbirdTurdus merulain North-Western Poland

Cited by 22 publications

References 10 publications

Age‐specific reproduction and disposable soma in an urban population of Common BlackbirdsTurdus merula

Age‐specific reproduction and disposable soma in an urban population of Common BlackbirdsTurdus merula

Survival costs of within‐ and between‐season mate change in the European blackbirdTurdus merula

Trading up: the fitness consequences of divorce in monogamous birds

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