Determinants of reproductive success in the Hoopoe Upupa epops, a hole-nesting non-passerine bird with asynchronous hatching

Factors affecting success of individual clutches and reproduction in the Ho opoe Upupa epops were studied over five years in a colour-ringed population in Granada, southern Spain. Pairs initiated between one and three breeding attempts per season (including replacement clutches), but only 19% laid a second clutch after raising one successful brood. Seasonal productivity ran ged from none to eight fledglings. The pairs that laid a second clutch obta ined slightly greater productivity than those that did not, although the di fferences were not significant, and productivity was not correlated with th e number of attempts initiated. Apparently, the reason that these differenc es were not greater was the higher predation rate suffered by second and re placement clutches. Predation accounted for 55% of nest losses, although tw o other major causes were nest desertion and death of females in the nest ( 17% each). The modal laying date of first clutches in the population was cl ose to the date when the productivity of first clutches was higher. This su ggests that, for most individuals, the costs of early laying exceed the ben efits of obtaining two broods due to differences in quality between them. S uccessful clutches produced one to six fledglings (mean 2.97) and the propo rtion of eggs per clutch that failed to produce fledglings in these success ful clutches was very high (49%). Most losses in successful clutches were d ue to death of chicks, which normally died very young and in a sequence det ermined by the hierarchy in the brood due to complete hatching asynchrony. The number of chicks fledged was positively correlated with the amount of f ood carried to the nest by parents. The patterns of nestling mortality and food delivery suggest that the Hoopoe is a brood reduction strategist that reduces 'optimistic' clutch sizes by selective starvation of the youngest c hicks through extreme hatching asynchrony.