1 Introduction

In an influential paper Kirch (1982) pointed out the potential for archaeology and ancillary studies of paleoenvironment to provide data on the impact Polynesians might have had on the environment of the Hawaiian Islands. He reviewed preliminary results from several studies of vegetation, fauna, and physical environment that he interpreted as indicating

"the endemic biota was drastically affected by . . . habitat destruction, with perhaps one-third to one-half of the known non-marine molluskan and bird faunas becoming extinct within the span of prehistoric human tenure" (Kirch 1982:11).

He predicted that future studies would confirm that "the prehistoric Polynesian inhabitants of Hawaii seriously transformed and, in many instances, degraded their island ecosystem" (Kirch 1982:11). Since then, evidence for change interpreted as this Polynesian transformation of the environment has appeared in studies of sub-fossil pollen (Athens and Ward 1991; Athens et al. 1992; Athens and Ward 1993; Ward 1981, 1990), avifauna (Olson and James 1982b,a, 1984, 1991; James and Olson 1991) and non-marine mollusks (Christensen and Kirch 1986; Kirch 1989; Christensen 1995; Cowie 1992). This paper reviews and reinterprets the stratigraphic record of non-marine mollusks (land snails) at Kalaeloa (or Barbers Point)¹, O`ahu.

Studies of sub-fossil land snails at Kalaeloa show a decline over time in the relative proportion of taxa believed to be locally or globally extinct today, and an increase in taxa that were "preadapted" (Kirch 1982:9) to disturbed conditions, and thus tolerant of the environmental changes inferred to have been wrought by Polynesians. A chronology based on ¹⁴C dates has been interpreted as placing these changes

"well within the period of Polynesian habitation of the islands . . . , providing strong circumstantial evidence that the Hawaiians were the cause of the ecological changes associated with this succession in the land snail fauna" (Christensen 1995:254).²

The Kalaeloa land snail data have been used to support the hypothesis that human activities on islands led to the extinction of many small creatures, in contrast to continental areas where extinctions were primarily among the megafauna, and that "(d)estruction of oceanic island biotas seems to have been more severe in the Holocene than it was historically" (Martin 1986:111). At Kalaeloa, forest clearance and habitat modification by Polynesians are commonly cited as causes of faunal extinctions (Kirch 1982; Christensen and Kirch 1986; Olson and James 1984).