By Jan TenBruggencate
Advertiser Columnist

Scientists digging in a limestone sinkhole at Maha'ulepu discovered remains that show Kaua'i's lowlands once had an amazingly rich array of bird life.

The sinkhole and cave lie just a few feet from the shore, and yet the bones include birds seen today in only the highest forests and birds that are now extinct.

More than 40 different bird species were identified from fossil bones in the sand and soil.

Fordham University biologist David Burney led the archaeological dig at the site, along with a range of experts from several disciplines. Bird bones were identified by Helen James and Storrs Olson of the Smithsonian Institution.

The initial results of the dig were printed in Ecological Monographs, a publication of the Ecological Society of America, under the title: "Fossil Evidence for a Diverse Biota from Kaua'i and Its Transformation since Human Arrival."

The bones included a range of seabirds, including petrels, shearwaters, boobies and frigatebirds.

Waterbirds include the Hawaiian goose, or nene; the Hawaiian duck, or koloa; the Laysan duck and four species of related birds that were extinct before Western contact, at least two of which were large and flightless. There also was an extinct flightless rail, the black-crowned night heron, and the now-endangered Hawaiian coot and Hawaiian stilt.

The fossil evidence shows that the small, yellowish Big Island high forest bird, the palila, was once a coastal bird on Kaua'i. The Hawaiian hawk, or 'io, was also on Kaua'i.

There were two species of owl, the pueo and an extinct long-legged owl, believed to be a bird-catcher. Avian experts believe the pueo, or short-eared owl, may not have appeared on the island until early Hawaiians introduced the rat.

Perhaps the most fascinating of the bird finds are bones that prove that almost all of what are now called Hawaiian upland forest birds were once common all the way to the shore.

Burney and his associates found 'o'o, 'elepaio, kama'o, puaiohi, 'o'u, nukupu'u, 'akialoa, 'anianiau, 'amakihi and 'apapane bones in the sinkhole, along with five extinct finches and an extinct relative of the 'akialoa.

Based on the dates of the layers in which bones were found, the scientists suggest extinctions occurred in three tiers, with "some species lost very early in Polynesian times, others declining as the human population increased, and the last disappearances occurring after European contact."

Two species of bat were found, one extinct and the other the surviving 'ope'ape'a.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Contact him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.