Within-year variation in clutch size has been claimed to be an adaptation to variation in the individual capacity to raise offspring. We tested this hypothesis by manipulating brood size to one common size, and predicted that if clutch size is individually optimized, then birds with originally large clutches have a higher fitness than birds with originally small clutches. No evidence was found that fitness was related to the original clutch size, and in this population clutch size is thus not related to the parental capacity to raise offspring. However, offspring from larger original clutches recruited better than their nest-mates that came from smaller original clutches. This suggests that early maternal or genetic variation in viability is related to clutch size. [KEYWORDS: life history; clutch size optimization; recruitment; Parus major; cross-fostering Tits parus-major; great-tit; brood size; reproductive success; ficedula-hypoleuca; juvenile survival; nestling weight; parent; heritability; density]
Original languageEnglish
JournalProceedings of the Royal Society B-Biological Sciences
Journal publication date1998

ID: 215988