Introduction to the European Science Foundation Technical Meeting: Analysis of Hormones in Droppings and Egg Yolk of Birds

Abstract

In 2002, a workshop entitled “Adaptations and Constraints in Avian Reproduction: Integrating Ecology and Endocrinology” took place in Wageningen, the Netherlands. The aim of the workshop was to build a network between scientists of different disciplines to exchange their knowledge and methods. This initiative resulted in the formation of the E-Bird network with the same name: “Adaptation and Constraints in Avian Reproduction: Integrating Ecology and Endocrinology.” Within this E-Bird framework we organized this technical meeting on the analysis of hormones from bird droppings and egg yolk, supported both by the European Science Foundation and the U.S.-based National Science Foundation (ESF and NSF). Starting in the late 1970s and early 1980s with pioneering studies in birds 1,2 and mammals, 3 noninvasive methods to measure steroid hormone levels in feces have been developed for an increasing number of species. 4 In birds, the term “fecal analysis” is a bit problematic, because feces and urine are excreted together in the form of droppings and in general, a complete separation of the fecal and urine fraction is not possible. 5 Hence, it may be more appropriate to speak of excreta or droppings. Increasing interest in noninvasive methods to monitor hormonal profiles in birds and other vertebrates, combined with common misconceptions about the ease of applying such methods, triggered the idea to organize this technical meeting. The intention was to discuss this method among a small group of experts and come up with some guidelines for its proper application. 6 During the organizational phase of the meeting it became clear that the analysis of hormones from egg yolk is accompanied by very similar methodological issues. Hence, we decided to extend the scope of the meeting and include the analysis of hormones from egg yolk. Although this meeting was held with a focus on birds, most contributions are of equal importance for studies in mammals and other vertebrates. Noninvasive methods to measure hormones from droppings have the major advantage that samples can be collected repeatedly with no handling stress. Hence, re