Frequent within-pair copulations during incubation in Northern Lapwings Vanellus vanellus are consistent with the sperm competition hypothesis

Abstract

Social partners of some bird species copulate during the incubation period; explanations for this include strengthening social bonds and/or reducing the risk of extra-pair paternity in consecutive clutches within the same season. According to current opinion, Northern Lapwings Vanellus vanellus exhibit this behavior, uncommon in shorebirds, in order to strengthen social bonds. Based upon field observations at 36 nests, I found that mating frequency increased after cessation of male incubation bouts, i.e., after the male had been unable to guard the female and prevent opportunities for extra-pair mating. This pattern is consistent with the sperm competition hypothesis: increased rates of copulation may be a way of devaluing the sperm of possible competitors and a strategy to secure paternity in subsequent clutches, which Northern Lapwings frequently lay throughout the breeding season. This explanation extends the previous interpretation of the frequent mating of Northern Lapwings during the incubation period.