Demography and movements of the endangered akepa and Hawaii creeper
1994; Wilson Ornithological Society; Volume: 106; Issue: 4 Linguagem: Inglês
ISSN
1938-5447
AutoresC. John Ralph, Steven G. Fancy,
Tópico(s)Wildlife Ecology and Conservation
Resumowe studied populations of the endangered Akepa (hxops coccineus coccineus) and Hawaii Creeper (Oreomystis mana) at four sites on the island of Hawaii. Mean monthly density (-t SE) of Akepa was 5.74 t 0.87, 1.35 + 0.41, 0.96 -+ 0.13, and 0.76 -+ 0.12 Akepa/ha at Kau Forest, Hamakua, Keauhou Ranch, and Kilauea Forest study areas, respec- tively. Hawaii Creepers were found at densities of 1.68 +- 0.53, 1.79 & 0.42, 0.48 & 0.06, and 0.54 2 0.08 birds/ha, respectively, at the four study areas. Highest capture rates and numbers of birds counted from stations occurred from August through November and February through March. Hatching-year birds were captured from May through December for Akepa and April through December for Hawaii Creeper. Annual survival for adults at Keauhou Ranch was 0.70 + 0.27 SE for 61 Akepa and 0.73 ? 0.12 SE for 49 Hawaii Creepers. Lowest rates of mortality and emigration occurred between May and August. Both species appeared to defend Type-B territories typical of cardueline finches, retained mates for more than one year, and showed strong philopatry. Home ranges for Hawaii Creepers (X = 7.48 ha) were larger than those for Akepa (X = 3.94 ha). No difference was found between home range sizes of males and females for either species. Received 21 Dec. 1993, accepted 20 April 1994. The Hawaii subspecies of the Akepa (Loxops coccineus coccineus) and the Hawaii Creeper (Oreomystis mana) are endangered Hawaiian honey- creepers (Fringillidae: Drepanidinae) found only in wet and mesic forests above 1000 m elevation on the island of Hawaii. The two species are similar in that they are insectivorous and occur at highest densities in native forests of ohia (Metrosideros polymorpha) and koa (Acacia koa) where they are mostly syntopic (Scott et al. 1986). Both species have extended breeding and molting periods that reflect the low degree of seasonality in their food supply and environment (Ralph and Fancy 1994a). Because they live in dense, remote rainforests, usually in low density, little is known about the life history of either species. The Akepa on Hawaii occurs in four disjunct populations totaling 14,000 birds, with highest densities in subalpine ohia woodland in the Kau Forest Reserve (Scott et al. 1986, Pratt et al. 1989). Akepa were once abundant and widely distributed on Hawaii (Perkins 1903). Pratt (1991) considered the Akekee on Kauai to be a separate species (L. caeruleirostris) and sug-
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