Light attraction in endangered procellariiform birds: Reduction by shielding upward radiation

-Autumnal attraction to man-made lighting causes heavy mortality in fledgling Hawaiian seabirds: Newell's Shearwater (PufJinus auricularis newelli), Dark-rumped Petrel (Pterodroma phaeopygia sandwichensis), and Band-rumped Storm-Petrel (Oceanodroma castro). These threatened, endangered, and rare species (respectively) approach and circle lights on their first flight from mountain nesting colonies on the island of Kauai to the sea. We shielded lights of the largest resort to prevent upward radiation on alternate nights during two fledgling seasons. Shielding decreased attraction by nearly 40%. Most attraction occurred 1-4 h after sunset. Full moon dramatically decreased attraction, a phenomenon that has both theoretical and management implications. Received 11 May 1984, accepted 16 November 1984. EACH autumn more than a thousand individuals of threatened and endangered seabirds are found on the ground in the vicinity of bright lights near the coast on the island of Kauai, Hawaii. These birds are mainly fledglings on their first flights from their mountain nesting colonies to the ocean. These disoriented birds collide with man-made structures and, if not killed on impact, may fall to the ground injured or stunned and there be run over or preyed upon. The threatened Newell's Shearwater [now treated as a subspecies of the Townsend's Shearwater (Puffinus auricularis newelli, A.O.U. 1983: 25; see Jehl 1982)], the endangered Hawaiian Dark-rumped Petrel (Pterodroma phaeopygia sandwichensis), and the very rare Band-rumped Storm-Petrel (Oceanodroma castro) all suffer mortality due to their attraction to man-made lights. The general problem of light attraction is worldwide among the Procellariiformes; at least 21 species are known to be attracted to man-made lights (Ridgway 1885, Wetmore 1926, Beebe 1935, Gross 1935, Murphy 1936, Murie 1959, Wingate 1964, Swales 1965, Jouanin and Gill 1967 in Imber 1975, Sincock and Swedberg 1969, Imber 1975, DeSante and Ainley 1980: 11). Here we report the results of a controlled experiment shielding upward radiation of lights in an attempt to understand more thoroughly the nature of light attraction and decrease its occurrence in procellariiform birds. Light attraction is a general problem in birds, not restricted to petrels or even to seabirds. Early authors noted the attraction of birds to fires (e.g. Murphy 1936), and lighthouses were the first man-made structures to attract birds (Clarke 1912). Ceilometer lights at airports caused heavy mortality until they were modified by shifting their spectra into the ultraviolet and turning them on only briefly (Howell et al. 1954, Laskey 1956, Terres 1956). An estimated one million migrants die at TV towers annually (Aldrich et al. 1966). Lights of a fishing vessel attracted 1.5 metric tons of Crested Auklets (Aethia cristatella), nearly capsizing the boat (Dick and Donaldson 1978). Birds are also attracted to gas flares on oil rigs in the ocean (Sage 1979). Such reports bear some striking parallels with light attraction in Hawaiian procellariiform birds. The commonest mountain-nesting species on Kauai is the threatened Newell's Shearwater, which was once believed to be extinct (Peters 1931) but was rediscovered in 1954 when one flew into a lighted window on the island of Oahu (Richardson 1955). By the mid-1960's Newell's Shearwaters were being found during October and November in all inhabited coastal areas of Kauai, apparently attracted to streetlights, lighting of athletic fields, security lights around hotels and resorts, and similar areas (Hadley 1961, King and Gould 1967, Sincock and Swedberg 1969). The first breeding colony was discovered in 1967 on a steep mountainside on Kauai (Sincock and Swedberg 1969). Nest predation by the introduced lesser mongoose (Herpestes auropunctatus) and domes377 The Auk 102: 377-383. April 1985 This content downloaded from 157.55.39.255 on Mon, 01 Aug 2016 06:02:41 UTC All use subject to http://about.jstor.org/terms 378 REED, SINCOCK, AND HAILMAN [Auk, Vol. 102 tic mammals probably accounts for the extirpation or near extirpation of Newell's Shearwater on Hawaiian islands other than Kauai; the mongoose is not yet known to be established on Kauai. In 1978 a systematic study of autumnal light attraction was initiated by Sincock and T. Telfer on Kauai; in the first year of the program 867 Newell's Shearwaters, now considered a threatened subspecies, were turned in at 11 "shearwater aid stations" on Kauai. More birds were picked up in following years, with 1,451 birds recovered in 1979, 1,358 in 1980, and 1,133 in 1981. An additional 100200 birds died on the highways each year. A few individuals of two rarer procellariiform species were also picked up. One of these, the endangered Hawaiian Dark-rumped Petrel, breeds in a small remnant colony on the inner slopes of Haleakala "crater" on the island of Maui and possibly rarely in a few other sites in the Hawaiian Islands, but no nest has yet been found on Kauai. Three fledglings were turned in on Kauai during the 1978 season, 5 in 1979, 3 in 1980, and 6 in 1981. The third species, the Band-rumped StormPetrel (formerly known as Harcourt's or Madeiran Storm-Petrel), is so rare in Hawaii that its nesting has not yet been confirmed. During a helicopter survey in 1980, we located the nest burrow of some species on a sheer cliff face in a valley where Sincock had heard Band-rumped Storm-Petrels calling during the breeding season. As our survey was made after nesting, no birds were at the burrow so we cannot say with certainty that the nest site belonged to this species. One individual was turned in during the 1978 fallout, 2 each in 1979 and 1980, but none in 1981.