Fossil Evidence for a Diverse Biota From Kaua‘i and Its Transformation Since Human Arrival

Abstract

Coring and excavations in a large sinkhole and cave system formed in an eolianite deposit on the south coast of Kaua'i in the Hawaiian Islands reveal a fossil site with remarkable preservation and diversity of plant and animal remains. Radiocarbon dating and investigations of the sediments and their fossil contents, including diatoms, invertebrate shells, vertebrate bones, pollen, and plant macrofossils, provide a more complete picture of prehuman ecological conditions in the Hawaiian lowlands than has been previously available. The evidence confirms that a highly diverse prehuman landscape has been completely transformed, with the decline or extirpation of most native species and their replacement with introduced species.The stratigraphy documents many late Holocene extinctions, including previously undescribed species, and suggests that the pattern of extirpation for snails occurred in three temporal stages, corresponding to initial settlement, late prehistoric, and historic impacts. The site also records land-use changes of recent centuries, including evidence for deforestation, overgrazing, and soil erosion during the historic period, and biological invasion during both the Polynesian and historic periods. Human artifacts and midden materials demonstrate a high-density human presence near the site for the last four centuries. Earlier evidence for humans includes a bone of the prehistorically introduced Pacific rat (Rattus exulans) dating to 822 yr BP (calendar year [cal yr] AD 1039-1241).Vegetation at the site before human arrival consisted of a herbaceous component with strand plants and graminoids, and a woody component that included trees and shrubs now mostly restricted to a few higher, wetter, and less disturbed parts of the island. Efforts to restore lowland areas in the Hawaiian Islands must take into account the evidence from this study that the prehuman lowlands of dry leeward Kaua'i included plants and animals previously known only in wetter and cooler habitats. Many species may be restricted to high elevations today primarily because these remote locations have, by virtue of their difficult topography and climate, resisted most human-induced changes more effectively than the coastal lowlands.

Hawaiian Birds: Lessons from a Rediscovered Avifauna

“…James 1982b, Carson andClague 1995 [Auk,Vol. 120 islands of Hawaii, Molokai, Maui, Lanai, Oahu, and Kauai James 1982b, 1991;Olson 1991, 2003;Burney et al 2001).…”

“…The excavation covered a period of ~10,000 years. Bones of 40-43 species of indigenous birds were recovered from that site, including waterfowl, pelagic seabirds, waders and shorebirds, rails, raptors, and passerines (Burney et al 2001). New fossil taxa include an odd duck with a fl attened cranium and small eyes and an endemic gull; there are no resident gulls in the modern Hawaiian avifauna, and no gulls have been collected at other fossil sites.…”

“…Bones of a koa-fi nch (Rhodacanthis) and Palila (Loxioides bailleui) were collected here, extending the known distribution of both taxa. DNA sequences have been obtained from several bones from that site (Burney et al 2001). Bones from more recent levels in the excavation have proven more likely to yield DNA sequence.…”

“…Radiocarbon dating of bones of extinct birds and presence of extinct birds in some archaeological sites have shown that extinctions on Hawaii occurred aft er humans colonized the archipelago, ~1,600 years ago (Olson and James 1982a, b;James et al 1987, Burney et al 2001. That patt ern of massive, rapid extinction of endemic birds following human colonization has been found on oceanic islands throughout the world (Steadman 1995).…”

Bayesian age-depth modelling of Late Quaternary deposits from Wet and Blanche Caves, Naracoorte, South Australia: A framework for comparative faunal analyses

“…Caves also provide stable conditions for the long term preservation of skeletal remains of a diverse range of vertebrates, which may have been collected through pitfall entrapment, cave inhabitant death and/or carnivore accumulation (Nielsen-Marsh, 2000). In some cases, vertebrate deposits in caves are associated with a range of other palaeoecological materials such as charcoal, calcium carbonate cave formations (speleothems) and pollen, which may be correlated with fossil faunal assemblages to provide a more accurate interpretation of past environmental conditions (e.g., Burney et al, 2001;Carrión et al, 2003;Auler et al, 2006). The application of Bayesian age-depth models to cave sequences has been valuable where the complex and sometimes random nature of accumulation processes in caves can limit the resolution and accuracy of chronologies for these sites (e.g., Jacobi and Higham, 2009;Blockey and Pinhasi, 2011;Pinhasi et al, 2011).…”