Data from: Decreased selectivity during mate choice in a small-sized population of a long-lived seabird

As biparental care is crucial for breeding success in Procellariiformes
seabirds (i.e., albatrosses and petrels), these species are expected to be
choosy during pair formation. However, the choice of partners is limited
in small-sized populations, which might lead to random pairing. In
Procellariiformes, the consequences of such limitations for mating
strategies have been examined in a single species. Here, we studied mate
choice in another Procellariiforme, Bulwer’s petrel Bulweria bulwerii, in
the Azores (ca 70 breeding pairs), where the species has suffered a
dramatic population decline. We based our approach on both a 11-year
demographic survey (capture-mark-recapture) and a genetic approach
(microsatellites, n = 127 individuals). The genetic data suggest that this
small population is not inbred and did not experience a genetic
bottleneck. Moreover, pairing occurred randomly with respect to genetic
relatedness, we detected no extrapair parentage (n = 35 offspring), and
pair fecundity was unrelated to relatedness between partners. From our
demographic survey, we detected no assortative mating with respect to body
measurements and breeding experience and observed very few divorces, most
of which were probably forced. This contrasts with the pattern previously
observed in the much larger population from the Selvagens archipelago
(assortative mating with respect to bill size and high divorce rate). We
suggest that the Bulwer’s petrels from the Azores pair with any available
partner and retain it as long as possible despite the fact that
reproductive performance did not improve with pair common experience,
possibly to avoid skipping breeding years in case of divorce. We recommend
determining whether decreased choosiness during mate choice also occurs in
reduced populations of other Procellariiform species. This might have
implications for the conservation of small threatened seabird populations.