DNA fingerprinting reveals a low incidence of extra-pair fertilizations in the lesser kestrel

Abstract

DNA fingerprinting of socially monogamous, colonially breeding lesser kestrels, Falco naumanni, revealed that three of 87 (3.4%) nestlings were illegitimate, and all three came from a single nest of 26 sampled (3.8%). Extra-pair paternity may have arisen through either extra-pair copulation (EPC) or mate replacement. The maximum level of extra-pair fertilization (EPF) was low (3.4%) compared to that found in other socially monogamous species and was also lower than predicted according to the frequency of EPCs in a previous study (6.7%). Paired females depend strongly on male provisioning throughout the breeding season and may refuse to engage in EPCs to prevent withdrawal of parental investment by their mates. The DNA analysis also indicated that two nestlings in two different nests resulted from intraspecific brood parasitism. The frequency of parasitized broods revealed by DNA fingerprinting (7.4%, N=27) was higher than that inferred from egg-marking during nest inspections (3.8%, N=52). Pair copulation rates are high in the lesser kestrel but occur in a context of low sperm competition (i.e. low frequency of both EPCs and EPFs). Instead of assuring paternity, frequent copulations may function in females to assess their mate's condition. Alternatively, copulations may have a pair-bond function or may reduce the availability of an individual to other potential mates.