Egg and skin collections as a resource for long-term ecological studies

Well labelled and reliable series of bird skins and eggs collected over long time-spans offer opportunities to determine environmentally induced changes in parameters of ecological interest, such as geographical range, the age structure of populations, clutch-size, and the timing of breeding and migration. They also reveal environmentally induced changes in morphology related to pollution and a changing food base. Finally, they can be used for various chemical analyses to determine the presence and effects of certain environmental pollutants and even, through stable isotopes, the geographic origins of particular birds and changes in their diets over time. The value of museum collections for these purposes is sufficiently high for us to recommend the resumption of the systematic accumulation of avian specimens for long-term ecological research, but this should only be done if adverse effects on conservation status can be avoided. One example is the long-term scheme to collect specimens of birds of prey found dead by the public in the U.K., which has resulted in several valuable conservation-oriented applications.