Copulation behaviour in the Southern Lapwing (Vanellus chilensis)

The Southern Lapwing (Vanellus chilensis) is a widespread bird across Southern America and commonly found in any large open areas, including agriculture and urban. Despite being a conspicuous species, little is known about its copulatory behaviour. In this research, we studied the copulation behaviour of Southern Lapwings and identified specific behaviours that preceded copulation events. Focal observations were made during one year on two pairs of lapwings that inhabit an urban area in the southeastern Pampas region, Argentina. A total of 110 intra-pair copulations were recorded (pair 1 = 64 and pair 2 = 46). Frequent copulations began 97 and 64 days before the first egg-laying, respectively, although the highest frequency occurred before the onset of the first nesting attempt. The Southern Lapwing copulated during all daylight hours, with a peak in the morning. Copulation occurred for up to five consecutive days, and the maximum number of copulations observed in a single day was four. Courtship and territory defence were the most common behaviours preceding copulation. Among the multiple hypotheses that have been proposed to explain frequent intra-pair copulation, our results seem to support two of them: the territory signalling hypothesis and the social bond hypothesis. The high population density coupled with the low availability of territories and a strong social bond based on cooperation and coordination could support both hypotheses, respectively. Given that the social environment can modify the behaviour of plovers, future research should evaluate the copulation behaviour at different population densities and the adaptive functional significance of this behaviour.