A specimen of Jouanin's petrel from Lisianski Island, northwestern Hawaiian Islands
No abstract available.
Condor↗
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Function of eye coloration in North American accipiters
Young nestling Cooper?s Hawks peck vigorously at red objects but do not peck at yellow objects. The significance of this response is discussed in relation to developmental changes in iris coloration in adult hawks.
Condor↗
A necropsy procedure for sampling disease in wild birds
This paper presents a necropsy procedure for examining small wild birds, designed to be used by investigators without experience in avian pathology. It gives instructions on how to conduct a postmortem examination, lists the needed equipment, tells what parts of a bird to save when a disorder in encountered, and lists possible diseases which each may signify. This procedure would enable ornithologists to include parasites and diseases in their investigations of avian populations.
Condor↗
Lead concentrations and reproduction in highway-nesting barn swallows
Swallows (Hirundo rustica) collected within the right-of-way of a major Maryland highway were greater than those found in Barn Swallows nesting within a rural area. Lead concentrations in the feathers of adults from the highway colony were also greater than Lead concentrations in the carcasses and stomach contents of adult and nestling Barn those of rural adults, but concentrations in the feathers of nestlings from the two locations were similar. Activity of u-aminolevulinic acid dehydratase in red blood cells was lower in highway-nesting adults and their young than in their rural counterparts, although hemoglobin concentrations and hematocrits did not differ. The number of eggs, nestlings, and body weights of the latter at 16-18 days of age were similar in the two colonies, as were body weights of adults from the two areas. These results suggest that contamination of roadside habitats by lead from automotive emissions does not pose a serious hazard to birds that are aerial feeders.
Condor↗
Shiny cowbird parasitism in two avian communities in Puerto Rico
The shiny cowbird (M. bonariensis), a brood parasite, has recently expanded its range from South America to Puerto Rico via the Lesser Antilles. This species is a host generalist and, on reaching Puerto Rico, encounteed avian species with no history of social parasitism. In mangrove habitat study areas, 42% of the resident non-raptorial land bird species were parasitized. Some species were heavily parasitized; e.g., yellow warbler (Dendroica petechia), 76% of nests parasitized black-whiskered vireo (Vireo altiloquus), 82%, Puerto Rican flycatcher (Myiarchus antillarum), 85%, yellow-shouldered blackbird (Agelaius xanthomus), 95%, troupial (Icterus icterus), 100%, black-cowled oriole (I. dominicensis), 100%. Others suffered low rates of parasitism (2-17% of nests examined); e.g., gray kingbird (Tyrannus dominicensis), red-legged thrush (Turdus plumbeus), bronze mannikin (Lonchura cucullata), northern mockingbird (Mimus polyglottos), greater antillean grackle (Quiscalus niger). Cowbird parasitism affected hosts by depressing nest success an average of 41% below non-parasitized nests and reducing host productivity. Parasitized host nests hatched 12% fewer eggs an fledged 67% fewer of their own chicks than non-parasitized pairs.
Condor↗
Phenotypic variation of the Mexican duck (Anas platyrhynchos diazi) in Mexico
A collection of 98 breeding Mexican Ducks (Anas platyrhynchos diazi) was made in Mexico from six areas between the United States border with Chihuahua and Lake Chapala, Jalisco, in order to study geographic variation. Plumage indices showed a relatively smooth clinal change from north to south; northern populations were most influenced by the Northern Mallard (A. platyrhynchos) phenotype. Measurements of total, wing, and culmen lengths and bill width were usually significantly larger in males at any one site, but showed no regular geographic trends. Hybridization between platyrhynchos and diazi phenotypes may or may not be increasing in the middle Rio Grande and Rio Conchos valleys; available data are insufficient to decide. A spring 1978 aerial census yielded an estimate of 55,500 diazi -like birds in Mexico. Populations of diazi appear to be as large as the available habitat allows; management should be directed towards increasing and stabilizing the nesting habitat; and the stability of the zone of intergradation should be investigated.
Condor↗
Larval dermestid beetles feeding on nestling snail kites, wood storks, and great blue herons
In recent years abdominal lesions attributable to larval dermestid beetles ( Dermestes nidum ) have appeared in nestling Snail (Everglade) Kites ( Rostrhamus sociabilis ), Wood Storks ( Mycteria americana ), and Great Blue Herons ( Ardea herodias ). Although it appears that most nestlings affected have survived, the degree of threat posed by dermestid larvae to various avian species is as yet unclear.
Condor↗
Nest sites and eggs of Kittlitz's and Marbled murrelets
Fourteen known and three probable nests of Kittlitz's Murrelet (Brachyramphus brevirostris) and eight known and one probable nest of Marbled Murrelet (B. marmoratus) have been reported. Nests of Kittlitz's Murrelet tend to be at higher elevations and farther inland than those of Marbled Murrelet. Kittlitz's nests have much less vegetative cover than Marbled nests. Nests of both species are generally a short distance below a peak or ridge, Kittlitz's on the ground and Marbled either in a tree or on the ground. The eggs of the two species are similar in color and their mean dimensions are not separable statistically. Our findings support the idea that Kittlitz's fledglings commonly get to the sea by way of streams.
Condor↗
Seabirds between Alaska and Hawaii
Seabirds were observed between Alaska and Hawaii along 158°W longitude from 24 October to 6 November 1976. Their distributions and abundances corresponded remarkably well to oceanographic regions. Indices of seabird density dropped in a series of plateaus from 44 birds/km 2 in the Alaska Current System to less than 1 bird/km 2 in subtropic waters. Northern distribution records were found for six species. The Subarctic Boundary marked the center of the separation between subarctic and subtropic pelagic avifaunas.
Alaska, Hawaii↗
Observations of emperor geese feeding at Nelson Lagoon, Alaska
Estuaries along the north side of the Alaska Peninsula provide essential habitat for most of the American population of Emperor Goose ( Chen canagica ) during migration (Petersen and Gill 1982). Most of the population passes through Nelson Lagoon in spring and fall, with over 40,000 birds recorded there (Gill et al 1981). Little is known about the feeding activity of Emperor Geese while they are in estuaries, and the importance of estuaries as staging areas during spring and fall migration is poorly understood. Here I report observations on the feeding activity of emperor Geese at one estuary (Nelson Lagoon).
Alaska↗
Ferruginous hawk nesting ecology and raptor populations in northern South Dakota
No abstract available.
Condor↗
Serum proteins of Canada goose (Branta canadensis) subspecies
Serum proteins from nine subspecies of Canada Geese (Brunta canadensis) were analyzed through the use of column and slab acrylamide electrophoresis. Variation was minimal within a subspecies, although all the subspecies were closely related. B. c. leucopareia appeared to be the most distinct subspecies, while maxima and moffitti were the most similar. Our preliminary findings suggest that the electrophoresis techniques are sensitive enough to identify some of the subspecies; however, baseline data from breeding ranges of all subspecies are required.
Condor↗
Pesticide concentrations in snail kite eggs and nestlings in Florida
From 1970-1977, unhatched snail kite eggs and young that were found dead at nests in Florida were analyzed by gas chromatography for residues of organochlorine pollutants. The 1970 and 1974 material showed measurable amounts of p,p'-DDE, p,p'-DDD, p,p'-DDT, and dieldrin. Dieldrin and polychlorinated biphenyl (PCB) residues were less than 0.1 ppm in the eggs and were detected in only one sample of muscle tissue at 0.11 ppm. Concentrations in ppm wet weight of p,p'-DDE, p,p' DDD, p,p'-DDT, dieldrin, and PCB for two samples of muscle and three of brain tissue (all 1977 material) were not detected at the limit of quantification (0.05 ppm).
Florida↗