Long-term fitness effects of fledging date in great tits

Reproductive decisions, such as timing of reproduction and the number of offspring to product, affect the conditions for the offspring at the time of independence These conditions can refer to the state of an individual, such as mass, or of the environment, such as time of the season, and will affect the reproductive value of the offspring. Knowledge of these fitness consequences is important when assessing the adaptive value of reproductive decisions. However it is often unclear how long- term the effect of these conditions is on an individual's reproductive success. Previous work has shown that the probability thar great tit fledglings recruit into the breeding population is strongly affected by their fledging date and mass. Using a long-term field study of a great tit population, we studied whether fledging conditions (fledging date, fledging mass and tarsus length) also affected reproductive success after an individual had recruited into the breeding population. For female recruits. this was not the case. For males, however, there was an effect of fledging date on lifetime reproductive success (LRS), calculated for individuals that had recruited. Males that fledged late produced fer er recruiting offspring in their first year of breeding partly because they had a twice as high probability that their breeding attempt failed to produce fledglings. Due to this decrease in LRS of recruited sons with increase in their hedging date, the fitness cost of breeding late is underestimated when counting the number of recruits produced from a breeding attempt. [KEYWORDS: Parus-major; clutch size; establishment; reproduction; dispersal; dominance; palustris]