The Viability of Small Populations of Birds: an Empirical Investigation of Vulnerability

The likelihood of the extinction of a significant portion of the world’s biota during the next several decades is cause for concern. This has given rise to the discipline of conservation biology, with the concomitant attempt to predict minimum viable population sizes (MVP) as one of its central themes. A substantial literature on MVP has arisen in the decade since the concept was introduced (Shaffer 1981; Schonewald-Cox et al. 1983; Soule 1986, 1987a; Simberloff 1988), but guidelines for estimating MVP have been based primarily on theoretical considerations (Simberloff 1988; Thomas 1990). There are good reasons for this bias.