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At least 343 records · Page 19Linked to original sources
USGS1978

Distribution and abundance patterns of the palila on Mauna Kea, Hawaii

Censuses of the known geographical range of the rare and endangered Palila were conducted in January (nonbreeding season) and September (breeding season) 1975. The habitat (mamane and naio forest of Mauna Kea, Hawaii) was divided into five major areas, with each analyzed for vegetational composition, phenology of the predominant tree species, and Palila density. Using a line transect census technique, we determined that: 1) the Palila occupied 5,560 ha, approximately 10% of its former range; 2) Palila populations were more restricted in the nonbreeding season, possibly reflecting their flocking tendency; 3) Palila densities were 38 birds per km2 in the breeding season and 36 birds per km2 in the nonbreeding season; 4) Palila population movements were small, and apparently were correlated with patterns of food availability; and 5) all methods of analysis yielded a projected population of approximately 1,600 birds. These low numbers, coupled with its restricted range, make the Palila one of the most vulnerable endangered species.

The Auk↗
USGS1978

Status and nesting of the yellow-billed cuckoo in Puerto Rico

Knowledge of the status of the Yellow-billed Cuckoo ( Coccyzus americanus ) in the Greater Antilles has been clouded by the bird's elusive behavior and spotty distribution on the islands, and by a major movement of North American migrants through the area to and from their wintering grounds in South America. Although Bond (1956) states that they breed in the Greater Antilles, nests are known only from Cuba, St. Croix (Bond 1956), and Jamaica (Lack 1976), and Bond considered the bird rare in Puerto Rico. Other students of Puerto Rican ornithology have suggested that the species is "uncommon" (Leopold 1963), "rare" (McCandless 1958), or a regular migrant or resident species (Wetmore 1916). Although no nests have been reported, most authors suspect that it breeds, and agree that it frequents coastal areas in western or southwestern Puerto Rico, primarily from May to September (Wetmore 1916, Danforth 1936, McCandless 1958, Leopold 1963, Biaggi 1970). From 1968 to 1971 we conducted linear strip censuses along pre-selected routes throughout the island, counting all birds heard or seen (Kepler and Kepler 1970); data we obtained on the Yellow-billed Cuckoo helped clarify and amplify existing information on its distribution and status.

The Auk↗
USGS1973

Propagation of barn owls in captivity

Some aspects of the biology and life history of native birds often are more readily obtained in captivity than in the field. This is particularly true in evaluating the effects of pesticides or other pollutants on birds, because establishing cause-and-effect relationships requires experimental studies. Few wild species have been bred in captivity with sufficient success to permit the large-scale studies that are needed. This paper reports successful efforts to breed Barn Owls ( Tyto alba prolinicol a) in captivity and presents biological data concerning reproduction.

The Auk↗
USGS1980

[Book review] Endangered Birds: Management techniques for preserving threatened species

This volume contains the proceedings of a symposium held at the University of Wisconsin-Madison, during 17-20 August 1977. In the words of the book's editor, Stanley Temple, the symposium "offered a unique opportunity for leading scientists from around the world to meet and share their experiences with endangered birds." That this objective was achieved is indicated by a list of contributors standing as a "Who's Who" in endangered species research and management. This symposium was jointly sponsored by the International Council for Bird Preservation, World Wildlife Fund, National Audubon Society, New York Zoological Society, and U.S. Fish and Wildlife Service. Fifty-one papers by 53 contributors are listed under 10 topics: endangered bird problems and the concept of managing threatened species; increasing reproductive effort and success by reducing nest-site limitations; alleviating problems of competition, predation, parasitism, and disease; supplemental feeding and manipulation of feeding ecology; manipulating aspects of nesting biology; captive breeding of endangered birds; genetic aspects of managing dwindling populations; reintroducing endangered birds to the wild; integrated approaches to management of endangered birds; and summary. A 14-page index provides convenient reference to subjects in the text.

The Auk↗
USGS1981

The structure of western warbler assemblages: Analysis of foraging behavior and habitat selection in Oregon

This study examines the foraging behavior and habitat selection of a MacGillivray's ( Oporornis tolmiei )-Orange-crowned ( Vermivora celata )-Wilson's ( Wilsonia pusilla ) warbler assemblage that occurred on early-growth clearcuts in western Oregon during breeding. Sites were divided into two groups based on the presence or absence of deciduous trees. Density estimates for each species were nearly identical between site classes except for Wilson's, whose density declined on nondeciduous tree sites. Analysis of vegetation parameters within the territories of the species identified deciduous tree cover as the variable of primary importance in the separation of warblers on each site, so that the assemblage could be arranged on a continuum of increasing deciduous tree cover. MacGillivray's and Wilson's extensively used shrub cover and deciduous tree cover, respectively; Orange-crowns were associated with both vegetation types. When the deciduous tree cover was reduced, Orange-crowns concentrated foraging activities in shrub cover and maintained nondisturbance densities. Indices of foraging-height diversity showed a marked decrease after the removal of deciduous trees. All species except MacGillivray's foraged lower in the vegatative substrate on the nondeciduous tree sites; MacGillivray's concentrated foraging activities in the low shrub cover on both sites. Indices of foraging overlap revealed a general pattern of decreased segregation by habitat after removal of deciduous trees. I suggest that the basic patterns of foraging behavior and habitat selection evidenced today in western North America were initially developed by ancestral warblers before their invasion of the west. Species successfully colonizing western habitats were probably preadapted to the conditions they encountered, with new habitats occupied without obvious evolutionary modifications.

The Auk↗
USGS1981

Importance of structural stability to success of mourning dove nests

Studies of nest-site selection and nesting habitats often involve a "characterization" of nests and of habitats in which nests are found. Our objective in the present work is to identify nest-site characteristics that are associated with variation in components of Mourning Dove ( Zenaida macroura ) fitness (e.g. the probability of a nest succeeding), as opposed to simply "characterizing" dove nest sites. If certain nest- site characteristics affect the probability that a nest will succeed, then we suspect that these characteristics will be associated with either concealment (the probability of detection by certain predators) or structural stability (the probability of eggs or entire nests falling to the ground as a result of wind, rain storms, parental activity, etc.). Although other workers agree that structural stability is an important determinant of Mourning Dove nesting success (e.g. McClure 1944: 384; Woolfenden and Rohwer 1969: 59), we are aware of no actual tests of this hypothesis.

The Auk↗
USGS1982

Nesting ecology of roseate spoonbills at Nueces Bay, Texas

We conducted a study in 1978-1980 of the nesting ecology of Roseate Spoonbills (Ajaia ajaja) in a relatively polluted environment at Nueces Bay, Texas. For 154 marked nests, the average clutch size was 3.0 eggs; 73% of the eggs hatched, and 87% of the nests were successful (hatched at least 1 young). The average nest success rate (total fledglings:total eggs) was 50% or 1.5 fledglings per total nests. Incubation began the day after the first egg was laid, and the incubation period for each egg was 22 days. Eggs hatched in the order that they were laid; the first and second eggs hatched on consecutive days, and the second, third, and fourth eggs hatched every other day. Nest composition and size were highly consistent, but nest placement varied considerably and was dependent on the vegetative configuration of the dredge-material islands. Growth rate of nestlings conformed to a 'standard' growth curve, where body weight of nestlings at fledging equaled that of adults. There was no difference in weight gain among siblings based on actual age. Nestlings fledged at about 6 weeks of age, when feather development was complete. At fledging, the bills of juveniles had almost reached adult width, but bill length was only 67% that of adults. In general, environmental pollutants were low (<2 ppm) in spoonbill eggs, though a few eggs contained elevated concentrations of DDE (up to 15 ppm, wet weight). Some eggshells were 5% thinner than those in museum collections, but the degree of thinning was not within the range known to cause population declines. We conclude that organochlorine pollutants are not adversely affecting spoonbill reproduction at Nueces Bay, Texas, though the area is surrounded by industries and agricultural lands. Apparently, spoonbills are less sensitive to these contaminants than are other aquatic species.

The Auk↗
USGS1986

Estimating nest detection probabilities for white-winged dove nest transects in Tamaulipas, Mexico

Nest transects in nesting colonies provide one source of information on White-winged Dove ( Zenaida asiatica asiatica ) population status and reproduction. Nests are counted along transects using standardized field methods each year in Texas and northeastern Mexico by personnel associated with Mexico's Office of Flora and Fauna, the Texas Parks and Wildlife Department, and the U.S. Fish and Wildlife Service. Nest counts on transects are combined with information on the size of nesting colonies to estimate total numbers of nests in sampled colonies. Historically, these estimates have been based on the actual nest counts on transects and thus have required the assumption that all nests lying within transect boundaries are detected (seen) with a probability of one. Our objectives were to test the hypothesis that nest detection probability is one and, if rejected, to estimate this probability.

The Auk↗
USGS1979

Annual weight cycle in wild screech owls

The annual weight cycle of wild birds of prey has received little attention in the past, primarily because of the difficulty in capturing and recapturing them. Screech Owls ( Otus asio ) are resident in our northern Ohio study area and readily occupy nest boxes established for Wood Ducks ( Aix sponsa ) (see VanCamp and Henny 1975). In addition to nesting in the boxes, the owls use them as roosting and feeding stations during the winter and are easily captured in the boxes during the day. Therefore, the owls presented an unusual opportunity to obtain information on their annual weight cycle. Between January 1975 and December 1978, Screech Owls were captured, weighed, and banded. Several were subsequently recaptured and weighed again to form the basis of this report. It is difficult to sex live Screech Owls in the field because they are not sexually dimorphic; however, Sherman (1911) noted that females did all of the incubating. We sexed adult owls with young at nest sites by the presence (female) or absence (male) of a brood patch. Owls captured away from nests during the nesting season without brood patches, or at other times of the year, were classified as sex unknown, unless they were previously captured at a nest with young. Screech Owls in northern Ohio have young in the nests from mid-April through early June.

The Auk↗
USGS1981

Colony site dynamics and habitat use in Atlantic coast seabirds

Seabird colony sizes and movements were documented in the DelMarVa coastal region in 1976-1977 and in New Jersey in 1978-1979. Most colonies were found on marsh and dredge deposition islands and on barrier island beaches. For the "traditionally" beach-nesting Herring Gull, Common Tern, and Black Skimmer, larger, more stable colonies were found on barrier beaches than on marsh islands. In marsh habitats, rates of colony-site change of marsh-nesting Forster's Tern and Laughing Gulls were similar to those of the former beach nesters. Several adaptations have evolved in marsh specialists to cope with a high risk of reproductive failure due to flooding, but both Herring Gulls and Common Terns also appear to be very adaptable in nesting under various habitat conditions. New colonies and those abandoned between years may be pioneering attempts by younger or inexperienced birds, because they are often smaller than persistent colonies, although patterns differ among areas and habitats. Colony-site dynamics are complex and result from many selective factors including competition, predation, physical changes in site structure, and flooding. The invasion of Herring Gulls into marshes along the mid-Atlantic coast has had an impact on new colony-site choice by associated seabirds. Calculating colony-site turnover rates allows for comparisons among species, habitats, and regions and may give useful insights into habitat quality and change and alternative nesting strategies.

The Auk↗
USGS1977

Woodcock nesting habitat in northern Wisconsin

Of 32 woodcock nests studied in northern Wisconsin, 29 were in forest stands dominated by aspen, and 3 were in northern hardwoods. Well-drained, upland nest sites near the brushy edges of poorly stocked poletimber stands were apparently preferred. More than 30 woody plant species were found at the 32 nest sites. Hazel was the most important shrub species noted.

The Auk↗
USGS1976

Reproductive rate and temporal spacing of nesting of red-winged blackbirds in upland habitat

The literature contains numerous studies on Red-winged Blackbird ( Agelaius phoeniceus ) reproduction. Francis (1971) summarized eight studies dealing with nesting success. These and other studies have also provided information on breeding chronology, clutch sizes, sex ratios, survival rates for eggs and nestlings, reproductive physiology, and other life history aspects of reproduction. With few exceptions, these studies have provided no data on the number of young fledged per female, per territorial male, or per unit area. This is especially true for upland nesting habitats where, at least in the midwestern United States, most Red-wings now nest (Graber and Graber 1963, Dyer et al. 1973). Also insufficient quantitative information is available on the extent and nature of renesting (i.e. nesting more than once in a nesting season) and on movements of adult females during the nesting season. A better understanding of these aspects of reproduction is critical for the development of an accurate population-dynamics model for the species. Such a model is sorely needed to evaluate the impact and effectiveness of proposed population management strategies in places where blackbirds are deemed a health or safety hazard, or cause damage to agricultural crops (Tosh et al. 1970, Solman 1971, Stone et al. 1972). This study had three objectives: (1) to determine the distribution, size, and number of Red-winged Blackbird territories for an old-field habitat; (2) to determine the number of nesting females, nesting success, extent of renesting, and number of young fledged for these territories; and (3) to examine movements of female Red-wings during the nesting season.

The Auk↗
USGS1989

Annual survival rates of breeding adult roseate terns

Analyses of the capture-recapture data on 910 individual Roseate Terns ( Sterna dougallii ) trapped from 1978-1987 as breeding adults on nests on Falkner Island, Connecticut, estimate the average annual minimum adult survival rate to be 0.74-0.75. There was weak evidence of year-to-year variation in annual survival rates during the study period. The Jolly-Seber models used to estimate survival rates also generated estimates of population size and capture probabilities. To determine the relative importance of adult mortality and permanent emigration in contributing to the estimated annual loss of one-fourth of the breeding population will require further study of intercolony movement between all the major colony sites. Assuming that the loss of birds from the Falkner Island colony site is due mostly to mortality rather than permanent emigration, and that the survival rate of this breeding population is typical of the entire North Atlantic breeding population, then the survival rate of this endangered species is low in comparison to the survival rates of several other marine bird species in the orders Procellariiformes, Pelecaniformes, and Charadriiformes.

The Auk↗
USGS1990

Comparisons of patch-use models for wintering American tree sparrows

Optimal foraging theory has stimulated numerous theoretical and empirical studies of foraging behavior for >20 years. These models provide a valuable tool for studying the foraging behavior of an organism. As with any other tool, the models are most effective when properly used. For example, to obtain a robust test of a foraging model, Stephens and Krebs (1986) recommend experimental designs in which four questions are answered in the affirmative. First, do the foragers play the same "game" as the model? Sec- ond, are the assumptions of the model met? Third, does the test rule out alternative possibilities? Finally, are the appropriate variables measured? Negative an- swers to any of these questions could invalidate the model and lead to confusion over the usefulness of foraging theory in conducting ecological studies. Gaines (1989) attempted to determine whether American Tree Sparrows ( Spizella arborea ) foraged by a time (Krebs 1973) or number expectation rule (Gibb 1962), or in a manner consistent with the predictions of Charnov's (1976) marginal value theorem (MVT). Gaines (1989: 118) noted appropriately that field tests of foraging models frequently involve uncontrollable circumstances; thus, it is often difficult to meet the assumptions of the models. Gaines also states (1989: 118) that "violations of the assumptions are also in- formative but do not constitute robust tests of predicted hypotheses," and that "the problem can be avoided by experimental analyses which concurrently test mutually exclusive hypotheses so that alter- native predictions will be eliminated if falsified." There is a problem with this approach because, when major assumptions of models are not satisfied, it is not justifiable to compare a predator's foraging behavior with the model's predictions. I submit that failing to follow the advice offered by Stephens and Krebs (1986) can invalidate tests of foraging models.

The Auk↗
USGS1990

Annual variation in foraging ecology of prothonotary warblers during the breeding season

We studied foraging ecology of Prothonotary Warblers ( Protonotaria citrea ) along the Tennessee River in west-central Tennessee during the breeding seasons of 1984-1987. We analyzed seven foraging variables to determine if this population exhibited annual variation in foraging behavior. Based on nearly 3,000 foraging maneuvers, most variables showed significant interyear variation during the four prenestling and three nestling periods we studied. This interyear variation probably was due -to proximate, environmental cues--such as distribution and abundance of arthropods - which, in turn, were influenced by local weather conditions. Researchers should consider the consequences of combining foraging behavior data collected in different years, because resolution of ecological trends may be sacrificed by considering only general patterns of foraging ecology and not the dynamics of those activities. In addition, because of annual variability, foraging data collected in only one year, regardless of the number of observations gathered, may not provide an accurate concept of the foraging ecology in insectivorous birds.

The Auk↗
USGS1990

Intersexual and temporal variation in foraging ecology of prothonotary warblers during the breeding season

We studied foraging ecology of Prothonotary Warblers ( Protonotaria citrea ) over four breeding seasons to determine if this species exhibited sex-specific or temporal variation in foraging behavior. Significant differences between sexes during the prenestling period were found for foraging height and substrate height (foraging method, plant species/substrate, perch diameter, horizontal location from trunk, and prey location were not significantly different). During the nestling period, this divergence between sexes was evident for foraging height, substrate height, substrate / tree species, and prey location. Additionally, male warblers significantly altered their behavior for all seven foraging variables between the two periods, whereas females exhibited changes similar to those of males for five of the foraging variables. This parallel shift suggests a strong behavioral response by both sexes to proximate factors (such as vegetation structure, and prey abundance and distribution) that varied throughout the breeding season. Sex-specific foraging behavior during the prenestling period was best explained by differences in reproductive responsibilities rather than by the theory of intersexual competition for limited resources. During the nestling period, neither hypothesis by itself explained foraging divergences adequately. However, when integrated with the temporal responses of the warblers to changes in prey availability, reproductive responsibilities seemed to be of primary importance in explaining intersexual niche partitioning during the nestling period. We emphasize the importance of considering both intersexual and intraseasonal variation when quantifying a species' foraging ecology.

The Auk↗
USGS1993

In memoriam: Arthur Bernard Singer, 1917-1990

Arthur Bernard Singer was born 4 December 1917, and died 6 April 1990. Although brought up in New York City, Arthur developed an early fascination with birds. His favorite haunts were the Bronx Zoo and the American Museum of Natural History, where Robert Cushman Murphy encouraged his efforts and where Arthur acquired a worldwide perspective. After graduating from Cooper Union Art School in New York City in 1939, he began his career as an art teacher, art director, and designer, His real interest, however, was in depicting the postures and plumages of birds and mammals. As early as 1941 his wildlife art was exhibited at the Bronx Zoo. While he was in the army, his wife Edith (“Judy”) helped mount this first exhibit; Arthur never saw the show.

The Auk↗