Better the devil you know: common terns stay with a previous partner although pair bond duration does not affect breeding output

Abstract

In a monogamous species two partners contribute to the breeding process. We study pair formation as well as the effect of pair bond length and age on breeding performance, incorporating individual heterogeneity, based on a high-quality dataset of a long-lived seabird, the common tern ( Sterna hirundo ). To handle missing information and model the complicated processes driving reproduction, we use a hierarchical Bayesian model of the steps that lead to the number of fledglings, including processes at the individual and the pair level. The results show that the age of both partners is important for reproductive performance, with similar patterns for both sexes and individual heterogeneity in reproductive performance, but pair bond length is not. The terns are more likely to choose a former partner independent of the previous breeding outcome with that partner, which suggests a tendency to retain the partner chosen at the beginning of the breeding career.

Environmental heterogeneity decreases reproductive success via effects on foraging behaviour

“…Reproductive success was, however, generally low; at all but one colony in this study (Coquet) kittiwakes reared less than one fledgling per nest on average. This may mean that the potential increase in reproductive success in more homogeneous environments is not worth the risk of switching breeding site, but instead is outweighed by other factors driving strong site fidelity common among seabirds such as pair bonds [74], familiarity with conspecifics [75] and natal philopatry [76]. Future study could, however, shed light on the effect of environmental heterogeneity on recruitment of prospecting breeders, as well as long-term population trends [77].…”

Mate fidelity improves survival and breeding propensity of a long‐lived bird

“…However, hypotheses focusing exclusively on annual breeding success may not adequately explain why pairs of some species remain in close proximity and coordinate efforts throughout the annual cycle. Furthermore, the mate familiarity hypothesis strictly applied to annual breeding output does not seem to address species where reproductive output does not improve with pair‐bond duration, yet pairs typically remain faithful (Rebke, Becker, & Colchero, 2017).…”

Female–female aggression in a cooperatively breeding bird during the non‐breeding period: the behavioral strategy to maintain long‐term partnerships

“…This is indicated by the fact that almost all widowers get mates and helpers consist of yearling males, which are more likely to fail in mate competition given that helping is a ‘best of a bad job' strategy (Zhang et al ). Female ground tits may also benefit from a long‐term partnership in terms of reducing sexual conflict (Nowicki et al ), or improving reproductive success (Griggio and Hoi , Sánchez‐Macouzet et al , but see Rebke et al ). Meanwhile, benefits from divorce such as avoidance of inbreeding or breeding failure (Culina et al ) are less conspicuous in the ground tits (incest rate 2.1%, complete brood loss < 0.5%; Tang et al ).…”