Mate Attentiveness, Seasonaltiming of Breeding and Long-term Pair Bonding in the House Finch

In seasonallybreeding birds, natural selection favors individualsthat begin breeding earlier in a year because they produce more or higher quality offspring than those that begin breeding later. Among the factors that in uence the timing of breeding, which include the age, health, competitive ability, or mate quality of individuals, is the longevity of the pair bond, with birds that remain mated across years initiating breeding earlier in the season than newly formed pairs. The behavioural interactions between pair members that may facilitate long-term pair bonding and early breeding onset have infrequently been studied, however. Here we report the relationship between male-female afŽ liative behaviour, pair-bond duration, and breeding date in house Ž nches (Carpodacusmexicanus), a short-lived, sociallymonogamous passerine species in which the duration of pair bonds is highly variable within and among seasons. Finches that initiated breeding earliest in the season were those that had bred with one another in previous years. Early breedingmales from returning pairs maintained signiŽ cantly closer contact with their mate during the Ž rst egg-laying period of the year than did males from late-breeding, newly formed pairs. Similarly, early-breeding females from returning pairs followed their mate more closely in nest-vicinity  ights during the fertile period than