Anti-predator behaviour and mating systems in waders: aggressive nest defence selects for monogamy

Abstract

Data collected from the literature on anti-predator behaviour, body weight and mating systems of 90 Holarctic waders are presented. Aggressive nest defence is correlated with body weight, heavy species being more likely to attack predators than are small species. Monogamy is common among large waders. Polygamy is generally restricted to small waders, and monogamous species are significantly more aggressive than polygamous species. Presumably, a certain body size is necessary to chase away predators, and being above this threshold size, two cooperating parents guard their nest and brood more efficiently than one parent. Small birds generally do not gain the same anti-predator advantage from monogamy as large birds, and this is presumed to explain the high frequency of polygamous mating systems in small waders.