Experimental assessment of mating opportunities in three shorebird species

Mating opportunities may differ between closely related species, although the evidence for such variation is scant. Here we compare remating opportunities and courtship behaviour between three shorebird species: the Kentish plover, Charadrius alexandrinus, the Kittlitzʹs plover, Charadrius pecuarius, and the white-fronted plover, Charadrius marginatus, using data and an experimental approach from a previous study of the Kentish plover. By experimentally creating unmated males and females, we found that remating opportunities differed between these closely related plover species: remating times were shorter for females than males in a Kentish plover population that had a male-biased adult sex ratio, and in which most brood care after hatching was carried out by males. In contrast, remating times were male-biased in the uniparental Kittlitzʹs plover and unbiased in the biparental white-fronted plover. Male Kentish plovers spent significantly more time on courtship than females, whereas courtship behaviour was not sex biased in the other two plover species. The mate removal experiments also provided insights into pair bond stability. In the Kittlitzʹs plover, all 16 newly formed pairs remained together after the release of their former mates from captivity, whereas newly established pairs were replaced by their former mates upon release in all 12 white-fronted plover pairs. Taken together, these results are important in highlighting interspecific variation in mating activities, and suggest that both operational sex ratio and pair bond stability may differ between closely related species. These variations, in turn, may influence mating systems and parental care.