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

Abstract

Factors affecting success of individual clutches and reproduction in the Hoopoe 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 ranged from none to eight fledglings. The pairs that laid a second clutch obtained slightly greater productivity than those that did not, although the differences were not significant, and productivity was not correlated with the number of attempts initiated. Apparently, the reason that these differences were not greater, was the higher predation rate suffered by second and replacement clutches. Predation accounted for 55% of nest losses, although two 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 close to the date when the productivity of first clutches was higher. This suggests that, for most individuals, the costs of early laying exceed the benefits of obtaining two broods due to differences in quality between them. Successful clutches produced one to six fledglings (mean 2.97) and the proportion of eggs per clutch that failed to produce fledglings in these successful clutches was very high (49%). Most losses in successful clutches were due to death of chicks, which normally died very young and in a sequence determined by the hierarchy in the brood due to complete hatching asynchrony. The number of chicks fledged was positively correlated with the amount of food 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 chicks through extreme hatching asynchrony. © 1999 Taylor & Francis Group, LLC.