Bio: Sheila Conant is an academic researcher from University of Hawaii. The author has contributed to research in topics: Population & Endangered species. The author has an hindex of 8, co-authored 15 publications receiving 289 citations.
TL;DR: The Hawaiian islands contain the most spectacular variety of landbirds ever discovered on remote oceanic islands and studies of geographic variation among subspecies on different islands and among populations within islands have revealed extensive divergence in characters such as sexual chromatism, nest sites and nest morphology.
Abstract: The Hawaiian islands contain the most spectacular variety of landbirds ever discovered on remote oceanic islands. The Hawaiian honeycreepers, having evolved from a presumably single founding species of cardueline finch, comprise most of this avifauna. Birds from at least three other families of passerines and five families of non-passerines also radiated in Hawaii. Recent discoveries of a fossil avifauna indicate that most radiations were more extensive than previously thought. Classical analysis of the radiation of Hawaiian birds, especially the honeycreepers, focused on characters related to acquisition of food. Recent studies of bill size and shape in relation to food resources, and of foraging mode in relation to interspecific competitors, provide models of how divergence in diet and/or bill morphology might have evolved. Studies of geographic variation among subspecies on different islands and among populations within islands have revealed extensive divergence in characters such as sexual chromatism, nest sites and nest morphology.
TL;DR: Experimental control of ant numbers on two pairs of small offshore islets dominated by either the big-headed ant, Pheidole megacephala or the tropical fire ant, Solenopsis geminata to investigate the influence of these species on seabird hatching success, fledging success and weight.
Abstract: Invasive ants are a significant conservation concern and can have far-reaching effects in ecosystems they invade. We used the experimental control of ant numbers on two pairs of small ( 20% of tissue on their feet) weighed significantly less than uninjured chicks and did not fledge. It is unclear if the chicks were being preyed upon or stung in defense of nearby ant colonies. Radical changes in invasive ant populations have been noted, and booming ant populations could cause short-term, but widespread damage to seabird colonies. The negative effects of invasive ants on seabirds may be difficult to detect, and therefore unknown or underestimated throughout the world where the two groups overlap.
TL;DR: This paper presents a meta-analysis of birds of Altai Region, Northern Xinjiang during June-July of 1991 and shows clear patterns of decline in monogamous and sexually reproducing birds of prey found in this region over the course of the year.
Abstract: CHRISTOPHER A. LEPCZYK,∗ NICO DAUPHINE,† DAVID M. BIRD,‡ SHEILA CONANT,§ ROBERT J. COOPER,∗∗ DAVID C. DUFFY,†† PAMELA JO HATLEY,§§ PETER P. MARRA,∗∗∗ ELIZABETH STONE,††† AND STANLEY A. TEMPLE‡‡§§§ ∗Department of Natural Resources and Environmental Management, University of Hawai‘i at Mānoa, Honolulu, HI 96822, U.S.A., email email@example.com †Zoological Society of London, Regent’s Park, London NW1 4RY, United Kingdom ‡Avian Science and Conservation Centre, McGill University, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada §Department of Zoology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, U.S.A. ∗∗Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, U.S.A. ††Pacific Cooperative Studies Unit, Department of Botany, University of Hawai‘i at Mānoa, Honolulu, HI 96822, U.S.A. §§Pamela Jo Hatley, P.A., P. O. Box 47477, Tampa, FL 33646-0113, U.S.A. ∗∗∗Smithsonian Migratory Bird Center, National Zoological Park, Washington D.C. 20008, U.S.A. †††Center for Wildlife Health Research, 24 Goss Road, Pownal, ME 04069, U.S.A. ‡‡Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, Madison, WI 53706, U.S.A. §§§Gaylord Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI 53706, U.S.A.
TL;DR: Because the Alaka'i studies were seminal in the development of the current AOU classification of Hawaiian native passerines, they defend that classification against recent challenges and further refine it.
Abstract: We observed, tape recorded, and photographed birds of the Alaka'i Plateau on Kaua'i, Hawai'i for one week during the summer of 1975. We observed all but one of the island's historically known species and compared the Alaka'i Plateau with the more accessible Koke'e area. Ours were the last studies before catastrophic changes in the Kaua'i avifauna and included many observations that cannot now be repeated. This retrospective report presents our findings in the light of subsequent events. Because our Alaka'i studies were seminal in the development of the current AOU classification of Hawaiian native passerines, we defend that classification against recent challenges and further refine it. The controversial genus Hemignathus is shown to be supported by a suite of synapomorphies of plumage, bill morphology, and vocalizations. We advocate removal of the 'Anianiau from Hemignathus and classify it as Magumma parva. Our studies of foraging behavior and vocalizations support the recent recognition of the Kaua'i 'Amakihi (H. kauaiensis) as a separate species and suggest that the 'Elepaio (Chasiempis) is best split into three species (sckzteri, ibidis, and sandwichensis). Major hurricanes in 1983 and 1992 appear to have severely impacted Alaka'i bird populations with the subsequent extinction of the Kaua'i '0'0 (Moho braccatus) and possibly the Kama'o (Myadestes myadestinus), and the island population of 'O'u (Psittirostra psittacea). We report some of the last natural history observations on these species. Formerly adaptive strategies for storm survival, including taking refuge in valleys, are no longer effective because the lowlands are now infested with mosquito-borne avian diseases. The Puaiohi (M. palmen'), a ravine specialist, suffered less from the storms although its population remains perilously low. Other forest birds, especially the 'Akikiki (Oreomystis bairdi), show noticeable declines since 1975. We speculate that intro- duced organisms such as alien plants can have a deleterious effect on ecosystems by altering feeding methods of birds even in areas where the weeds do not occur. We caution against the overly conservative use of species- level taxa for setting conservation priorities on remote islands. Received 24 October 19%, accepted 27 June 1997.
TL;DR: The status of Laysan Albatross populations at Kaena Point and Kuaokala on the island of Oahu, Hawaii is reported and new demographic data for this species is provided, indicating these colonies may serve as refugia in the event of sea level rise and, thus, should continue to be conservation priorities.
Abstract: Laysan Albatross (Phoebastria immutabilis) began re-colonizing sites across the Pacific in the 1970s after severe population declines, and fledged the first chick on the island of Oahu in 1992. We report the status of Laysan Albatross populations at Kaena Point and Kuaokala on the island of Oahu, Hawaii and provide new demographic data for this species. Colonies on Oahu were monitored weekly from 2004 to 2008; all individuals were censused, banded, and genetically identified to gender. There was a population of 365 adults on Oahu in 2008 of which 47% were active breeders. The breeding population increased 27% annually since 1991. The high rate of increase was due primarily to immigration with some local recruitment. Recaptures indicate that seven birds were from French Frigate Shoals, one was from Midway Atoll, and 52 were from Oahu and returning to breed; all other adults were of unknown origin. Hatching rate (62%), fledging rate (78%), and overall reproductive success (48%) were comparable to o...
01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.
TL;DR: It is suggested that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals.
Abstract: Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientific data. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact.
TL;DR: The ability to adapt to marginal habitats, in which survival and reproduction are initially poor, plays a crucial role in the evolution of ecological niches and species ranges as mentioned in this paper, but adaptation to marginal habitat may be limited by genetic, developmental, and functional constraints, but also by consequences of demographic characteristics of marginal populations, which makes them demographically and genetically dependent on core habitats and prone to gene flow counteracting local selection.
Abstract: The ability to adapt to marginal habitats, in which survival and reproduction are initially poor, plays a crucial role in the evolution of ecological niches and species ranges. Adaptation to marginal habitats may be limited by genetic, developmental, and functional constraints, but also by consequences of demographic characteristics of marginal populations. Marginal populations are often sparse, fragmented, prone to local extinctions, or are demographic sinks subject to high immigration from high-quality core habitats. This makes them demographically and genetically dependent on core habitats and prone to gene flow counteracting local selection. Theoretical and empirical research in the past decade has advanced our understanding of conditions that favor adaptation to marginal habitats despite those limitations. This review is an attempt at synthesis of those developments and of the emerging conceptual framework.
TL;DR: Handbook of North American Birds Edited by Ralph S. Palmer as mentioned in this paper, vol. 1: Loons through Flamingos. Pp. vii + 567 + 6 plates.
Abstract: Handbook of North American Birds Edited by Ralph S. Palmer. Vol. 1: Loons through Flamingos. Pp. vii + 567 + 6 plates. (New Haven, Conn., and London: Yale University Press, 1962.) 105s.
TL;DR: These findings support previous studies documenting high susceptibility of native Hawaiian forest birds to avian malaria and suggest this disease continues to threaten remaining high elevation populations of endangered native birds.
Abstract: Native Hawaiian forest birds are facing a major extinction crisis with more than 75% of species recorded in historical times either extinct or endangered. Reasons for this catastrophe include habitat destruction, competition with non-native species, and introduction of predators and avian diseases. We tested susceptibility of Iiwi (Vestiaria coccinea), a declining native species, and Nutmeg Mannikins (Lonchura punctulata), a common non-native species, to an isolate of Plasmodium relictum from the island of Hawaii. Food consumption, weight, and parasitaemia were monitored in juvenile Iiwi that were infected by either single (low-dose) or multiple (high-dose) mosquito bites. Mortality in both groups was significantly higher than in uninfected controls, reaching 100% of high-dose birds and 90% of low-dose birds. Significant declines in food consumption and a corresponding loss of body weight occurred in malaria-infected birds. Both sex and body weight had significant effects on survival time, with males more susceptible than females and birds with low initial weights more susceptible than those with higher initial weights. Gross and microscopic lesions in malaria fatalities included massive enlargement of the spleen and liver, hyperplasia of the reticuloendothelial system with extensive deposition of malarial pigment, and overwhelming anaemia in which over 30% of the circulating erythrocytes were parasitized. Nutmeg Mannikins, by contrast, were completely refractory to infection. Our findings support previous studies documenting high susceptibility of native Hawaiian forest birds to avian malaria. This disease continues to threaten remaining high elevation populations of endangered native birds.