Data from: Survival costs of within- and between-season mate change in the European Blackbird

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.

诸多针对社会单配制鸟类的研究均探讨了跨季更换配偶的适应性意义，但仅有少数研究从存活率提升的视角论述了配偶忠诚（pair fidelity）的益处。此外，目前尚无研究阐述季内保留配偶的相关益处。本研究以城市种群的欧洲黑鸫（European Blackbird，Turdus merula）的观测数据为基础，得以检验存活率与配偶忠诚之间的关联。由于乌鸫会在季内与跨季发生配偶离异行为，本研究得以检验配偶忠诚对其季内、跨季存活率以及配偶维系的影响。为此，本研究采用了多事件标记重捕（multievent capture-mark-recapture, MECMR）统计模型，该模型以重捕率以及不同配偶状态（对现有配偶忠诚、与新配偶配对、个体死亡）为基础。研究结果显示，季内与跨季存活率均与配偶状态相关：无论雌雄，配偶结合时长均可提升个体至下一次重捕时段的存活率。研究发现，与当前配偶的结合时长可提升个体在下一个繁殖季与原配偶再度配对的概率，但未发现雌性的季内配偶结合时长存在此类影响。研究结果还显示繁殖季末的配偶选择存在性别差异：雌性在次年与当年新配配偶再度繁殖的概率显著更低。本研究证实了季内与跨季存活率均与配偶保留行为相关，文末我们将围绕寻找新配偶如何影响鸟类存活率这一议题展开讨论。