Costs, benefits and constraints in the evolution of avian reproductive tactics: a study on the blue tit

In this study I have investigated the various factors influencing reproductive tactics among breeding blue tits (Parus caeruleus). The study was carried out in a nestbox-breeding population of marked individuals at the Revinge Area, outside Lund, southern Sweden. I have especially investigated the energetic, physiological and temporal factors influencing the reproductive decisions. This included use of various physiological methods such as metabolic measurements of energy expenditure, measurements of immunocompetence using ELISA:s and sexing of nestlings using quantification of DNA-contents using flow cytometry. Three themes were explored: 1/Reproductive effort and costs of reproduction, 2/sex allocation and 3/reproductive timing in a seasonal environment.