GENETIC PARENTAGE AND VARIABLE SOCIAL STRUCTURE IN BREEDING SOUTHERN LAPWINGS

We examined the genetic mating system and social breeding structure of the Southern Lapwing (Vanellus chilensis), a shorebird that breeds in Brazil in secluded pairs or groups (3–4 adults). We never observed copulation between males or females of primary pairs with additional adults in groups; all recorded copulations were between primary pair members. Where DNA from primary males was available, we found mixed paternity in 18.8% of the broods (3 of 16), comprising 9.8% of the chicks (4 of 41). All broods containing young sired by different males occurred in groups. One chick had a DNA fingerprint with four novel bands but shared a high proportion of bands with both primary pair members of its group. One explanation is that the chick's mother copulated with a relative of her social mate. However, quasi parasitism (i.e., nest-sharing by two females) cannot be excluded. Our study demonstrates a flexible social and genetic mating system in Southern Lapwings.