Data from: Survival costs of within‐ and between‐season mate change in the European Blackbird (Turdus merula)

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.

诸多针对社会性单配制鸟类的研究均探讨了季间配偶更换的适应性意义，但仅有少数研究从存活率提升的维度阐释了配偶忠诚的益处。此外，目前尚无研究阐述季内配偶留存的相关益处。本研究以城市种群的欧洲乌鸫（Turdus merula）为研究对象，得以检验存活率与配偶忠诚度之间的关联。由于乌鸫存在季内与季间的配偶离异现象，我们得以探究配偶忠诚度对其季内、季间存活率以及配偶忠诚行为的影响。为此，我们采用了基于重捕率与不同配偶状态（与原配偶相守、与新配偶配对、个体死亡）的多事件捕获-标记-再捕获（multievent capture-mark-recapture, MECMR）统计模型。本研究结果显示，季内与季间的存活率取决于配偶状态：无论雌雄，配偶关系存续时长均可提升其下一次重捕时的存活概率。研究发现，与当前配偶的关系存续时长可提升下一次繁殖季仍与该配偶配对的概率，但未发现雌性的季内配偶关系存续时长存在此类影响。研究结果还显示，繁殖季末期的配偶选择存在性别差异：雌性在次年与当年新配偶进行繁殖的概率显著更低。本研究证实了季内与季间的存活率取决于配偶留存行为，并围绕寻找新配偶如何影响鸟类存活率这一议题展开了讨论。