Collection of Embryos from Darwin’s Finches (Thraupidae, Passeriformes)

INTRODUCTION

There are no breeding colonies of Darwin’s finches anywhere in the world. Thus, all of the embryonic material is collected in the wild. This protocol describes how, in a field setting, fertilized eggs are collected and incubated at a precise temperature and how the resulting embryos are harvested and processed for in situ hybridization, antibody staining, and microarray analyses. In addition, the protocol includes steps for preparing the heads of older embryos for histological staining of bone and cartilage with alcian blue and alizarin red. It is likely that the same or similar methods can be used to obtain embryonic tissue from other species of songbirds. The main limitation of this protocol is that, when used in the field without external constant electricity sources, it requires power generators that need to run on a more or less constant basis, as well as stockpiles of supplies (fuel, oil, and fresh water).