Mate fidelity in a polygamous shorebird, the snowy plover (Charadrius nivosus)

Abstract

Social monogamy has evolved multiple times and is particularly common in birds. However, it is not well understood why some species live in long‐lasting monogamous partnerships while others change mates between breeding attempts. Here, we investigate mate fidelity in a sequential polygamous shorebird, the snowy plover (Charadrius nivosus), a species in which both males and females may have several breeding attempts within a breeding season with the same or different mates. Using 6 years of data from a well‐monitored population in Bahía de Ceuta, Mexico, we investigated predictors and fitness implications of mate fidelity both within and between years. We show that in order to maximize reproductive success within a season, individuals divorce after successful nesting and re‐mate with the same partner after nest failure. Therefore, divorced plovers, counterintuitively, achieve higher reproductive success than individuals that retain their mate. We also show that different mating decisions between sexes predict different breeding dispersal patterns. Taken together, our findings imply that divorce is an adaptive strategy to improve reproductive success in a stochastic environment. Understanding mate fidelity is important for the evolution of monogamy and polygamy, and these mating behaviors have implications for reproductive success and population productivity.

Successful breeding predicts divorce in plovers

“…For example, arctic bird species have typically short breeding seasons due to the harsh and stochastic environmental conditions, and tend to exhibit high fidelity to a mate, which is likely to improve offspring survival 17 , 18 . In contrast, mild environments in temperate and tropical regions tend to provide a more prolonged breeding season so that an individual might initiate multiple clutches with the same or different mates 1 , 19 , 20 . The influence of environmental conditions on mating decisions has been observed in a variety of taxa including flies, fish, frogs and birds 21 – 23 .…”

“…It has also been suggested that divorcing and rapidly changing a mate may be favoured by some species in order to make the most out of a restricted time budget (e.g. short life span or short breeding season) 1 , 40 .…”

“…Studies also suggest that mate fidelity can be a by-product of site fidelity 28 , 46 , and conversely, mate change can be a result of changing nest sites 47 , 48 . Nonetheless, studies of mate fidelity mostly centre around socially monogamous bird species between years 28 , 49 , and studies that investigate mate fidelity in multiple species and populations that exhibit variable duration of pair-bonds within a single breeding season are scarce 1 .…”

“…In a recent study, Halimubieke et al . 1 reported that snowy plovers ( Charadrius nivosus ), especially females, are more likely to divorce after successful nesting, simultaneously deserting their current brood, and initiate a new breeding attempt with a different mate, whereas, pairs tend to stay together after failed breeding attempts and initiate a second nesting attempt with the same mate. Divorcing individuals reared more offspring than those that retained their mates.…”

CeutaOPEN: Individual-based field observations of breeding snowy ploversCharadrius nivosus

“…1). Previously, we have used subsets of these data to report on a wide variety of topics in organismal biology, including sex ratio variation 12 , population viability 13 , courtship behaviour 14 , incubation behaviour 15 , parental care 16 , ontogeny 17 , chronobiology 18 , camouflage mechanisms 19 , offspring desertion 20 and mating system dynamics 21 . The motivation for making our database open is to provide evolutionary ecologists with an accessible resource that will serve as an important repository for addressing overarching questions in organismal biology and conservation.…”