| Summary: | I studied the reproductive behaviour of the great tit (<i>Parus major)</i>, looking in detail at the factors influencing parental investment decisions made before and after hatching. Using playback experiments and brood-size manipulations, I found that nestling begging behaviour and partner provisioning rates independently influenced the rate at which food was brought to the nest during chick rearing. In general, females has more control over parental provisioning rates than either their partner or their offspring. Males, in turn, had greater control over food delivery rates than offspring. During egg laying, females appeared to optimise egg investment according to their own provisioning capabilities, measured via provisioning levels to a standard brood size. By removing eggs as they were laid, and therefore inducing females to lay more eggs than they intended, I found a trade-off between egg-laying and chick-provisioning levels. The more eggs a female laid, the less able she was to care for the young after hatching. Females may benefit from advertising their reproductive strategies, and this possibility was explored with a cross-fostering experiment. I found that variation within the female breast stripe revealed information regarding alternative female reproductive strategies within the current reproductive attempt. Females with small, narrow breast stripes invested more pre-hatching; they laid heavier eggs and their chicks grew faster when reared by foster parents. By contrast, females with large, wide breast stripes invested more post-hatching; the chicks they reared grew faster. Additionally, females laid heavier eggs if they were paired with a male that had a wide stripe, which may reflect differential allocation for indirect benefits.
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