Internet Archaeol. 10, Dye

1.0 Introduction

In an influential paper Kirch (1982) pointed out the potential for archaeology and ancillary studies of palaeoenvironment to provide data on the impact Polynesians might have had on the environment of the Hawai'ian 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 Hawai'i 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 1982a; 1982b; 1984; 1991; James and Olson 1991) and non-marine molluscs (Christensen and Kirch 1986; Kirch 1989; Christensen 1995; Cowie 1992). This paper reviews and reinterprets the stratigraphic record of non-marine molluscs (land snails) at Kalaeloa (or Barber's Point), O`ahu (The Hawai'i House of Representatives, voted in April 1995 to restore the name Kalaeloa to this region of O`ahu (Honolulu Advertiser 1995)).

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 Hawai'ians were the cause of the ecological changes associated with this succession in the land snail fauna' (Christensen 1995, 254). 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).

In this paper we show that the interpretation of Polynesian influence drawn from the stratigraphic record of sub-fossil land snails at Kalaeloa is based on a unique stratigraphic sequence at a single sinkhole. The interpretation was then applied to other land snail sequences, despite their lack of evidence for Polynesian influence. We present a reanalysis of the stratigraphic record to conclude that Polynesians had little, if any, effect on land snail populations in sinkholes. We show that directional change in land snail populations was underway before Polynesians colonised the islands. Decreases in the diversity of snail populations, possibly indicative of environmental stress, do occur near the end of the stratigraphic sequence. Based on available dating evidence, however, these changes probably took place in the post-Contact period when the regional environment was radically altered by sugar cane cultivation.