1. The hypothesis that late breeding entails reproductive costs to birds was tested by comparing breeding traits of control and delayed great tit Parus major cl...

Capsule Nestling provisioning rates depend on nestling age and number, and on time of season, but not on time of day. Aims To determine patterns of nestling provisioning, the effort made by the parents, and the factors which affect them. Methods Mechanical counters to determine food provisioning patterns in 229 Great Tit Parus major nests over 4 years. Results Feeding frequency per chick showed a linear increase with nestling age and total feeding frequency stabilized towards the end of the nestling period. The number of visits per nest increased linearly, while those per nestling decreased linearly with brood‐size. Feeding rates per nest declined throughout the breeding season parallel to the seasonal brood‐size decline; feeding frequencies per nestling did not vary seasonally. Adult effort was almost constant throughout the day, independently of variations in brood‐size, ambient temperature and date. Conclusion Previous studies of nestling provisioning patterns were either contradictory or poorly supported by low sample sizes. The present study involved a much larger sample and clarifies nestling provisioning patterns and the factors with which they are associated.