History of endemic Hawaiian birds: Part I: population histories, species accounts: freshwater birds: Hawaiian Stilt Ae´o

Abstract

Himantopus mexicanus knudseni is a slim, medium-sized black and white wading bird with long black bill and red legs. It is resident on five islands - Kaua´i, O´ahu, Moloka'i, Maui, Hawai´i, and on Ni´ihau after seasonal winter rains. Exhaustive search of literature and government reports uncovered some 5,429 observational notes, collection records, census reports and related statements on relative abundance and geographical distribution from 1870 to 1983. Data are serially numbered, arranged in geographical and chronological order, referenced and systematically reviewed. Analysis of census records in recent years indicates a total pre-breeding population of about 900 of these birds distributed as follows among the various islands: Kaua'i, 144 (16%); Ni´ihau, 135 (15%); O´ahu 324 (36%) ; Moloka´i 9 (1%); Maui, 261 (29%); and Hawai´i 18 (2%) recent post-breeding populations averaging 1,100 individuals were found to be distributed as follows: Kaua'i 286 (26%); Ni'ihau, 44 (4%); O'ahu 495 (45%); Moloka'i, 22 (2%); Maui, 242 (22%); and Hawai´i 22 (2%). It is postulated that mortality factors and annual average production of about 200 young results in a population turnover every 5 years. The total population is judged to be relatively stable long-term.