Extinction & Biogeography of Tropical Pacific Birds (review)

I first had the opportunity to work on a tropical island as an undergraduate student in the early 1990s and quickly became fascinated with the diverse array of flora and fauna that surrounded me. Archaeologically I was just as enthralled, for it seemed to me, at least on the surface, that these islands must have been harsh places to live, yet at the same time richly abundant in resources to prehistoric settlers. I must admit that this superficial perception of island life quickly evaporated as I began researching some of the common themes in island archaeology. In the process, I encountered the growing body of evidence in the Caribbean and Pacific suggesting that humans had over-exploited, or had impacted in some fashion, island environments long before the arrival of Europeans. During this initial launch into my archaeological career, more often than not I found myself reading David Steadman's research on fossil bird life in the islands which began to pique my interest even further in human-insular biota relationships.

Extinction & Biogeography of Tropical Pacific Birds is a recent synthesis of Steadman's work in Oceania. The book is divided into 22 chapters spread across four main parts that lead off with a background on Pacific Island environments and culture history (Part I). The book then moves on to a summary and inventory of birds that have been found or recovered archaeologically from the major regions of the Pacific (Part II). The third section provides an overview of the main avifauna known from the islands (megapodes, rails, pigeons and doves, parrots, other nonpasserine landbirds, passerines, and seabirds). The final section (Part IV) is comprised of seven chapters that discuss major issues in the study of birds (e.g., equilibrium and turnover, conservation biology). Although specific to the tropical Pacific, many of these chapters will be of great interest to ornithologists, island biogeographers, and archaeologists whose expertise lies outside the region.

As Steadman acknowledges, there have been many attempts by biologists to inventory the species richness and diversity of organisms in the Pacific. However, these early surveys were often inadequate in their coverage and lacked methodological rigor. Yet, they still managed to form the basis for developing intricate models and theories on the dispersal and colonization of island taxa, extinction rates, and reasons for explaining the decrease in species richness known as "faunal attenuation" (in this case, "the overall west-to-east decline in taxonomic diversity of landbirds in Oceania"; 430). It is now known that the baselines set by these previous studies were inaccurate for modeling the distribution of Pacific Island fauna, helped in large part by an array of increasingly sophisticated techniques used by archaeologists and their close disciplinary cousins in the biological, environmental, and geological sciences. "[O]ur descriptive knowledge of the distributions of Polynesian landbirds has been so incomplete as to be deceptive" (xi) and "[e]ven values for species richness that incorporate the species lost to human impact are underestimates of the true number of species that an island would sustain today under natural conditions" (xi).

The fact remains that peoples who first encountered the pristine island environments of the Pacific were really no different than humans elsewhere—they exploited their environments, brought with them non-native plants, animals, and insects, successfully adapted to changing conditions, and grew steadily in population. All of these behaviors and more had the cumulative effect of impacting local biota and birds are certainly no exception. But what makes them different from other animals, as Steadman notes, was their relative abundance compared to other terrestrial animals, initial naïvety toward humans (making many of them easy to prey upon), and their extreme susceptibility to animals introduced during human colonization such as the rat. Habitat destruction due to land clearance did nothing to help the situation.

What makes...