Introduction

In Chapter 2 it was argued that nest building has been a feature of the biology of birds since their origin, and has had a key role in shaping the relationship in bird reproduction between parents and offspring. The prevalence in birds of biparental care (Ligon 1993) and the universal occurrence of egg laying (Blackburn & Evans 1986) are apparently important manifestations of this. During the evolution of bird nests, designs have become diverse, particularly in the passerines, the order that contains 59% of all living species of birds compared with 41% for all the 22 non-passerine orders put together (Sibley & Monroe 1990). As there is no fossil record of bird nests, can the pattern of diversification of bird nests be mapped? Has the appearance of new nest designs altered the rate of evolution (in particular of speciation)? Do nest characteristics such as those described in Chapter 5 provide reliable evidence for the reconstruction of bird phylogeny? These are matters for consideration in this chapter.

Collias (1997) distinguishes three types of nest based on their overall architecture: hole, open and domed nests. Examining the handful of families considered to be among the most primitive of the passerines, i.e. (in the sub-order Tyranni) the Eurylaimidae (broadbills), Formicariidae (ground antbirds), and Rhinocryptidae (tapaculos), and (in the sub-order Passeri) Menuridae (Australian lyrebirds) (Sibley et al. 1988, Sibley & Monroe 1990), he finds all three basic nest types represented.