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At least 901 records · Page 50Linked to original sources
USGS1990

Western grebe, Aechmophorus occidentalis, wintering biology and contaminant accumulation in Commencement Bay, Puget Sound, Washington

Western Grebes wintering at the head of Commencement Bay (bordering the waterways) accumulated significant amounts of mercury, arsenic, DDE, PCBs, chlordanes, and perhaps cadmium and HCB between 17 October 1985 and 6 February 1986. No change in selenium or lead was detected, but copper declined significantly. Western Grebes were likely to accumulate even higher levels of certain contaminants because they remained in Commencement Bay for an additional 3 months after the final collection. Remige moult and bursa length were used to separate five individuals believed to represent one age class, from the remainder of the October collection. These birds, perhaps nonbreeders spending one continuous year in Puget Sound, contained the 5 highest PCB, 5 of the 8 highest DDE, and 2 of the 3 highest mercury concentrations. No evidence was found in the literature to suggest the contaminant concentrations we reported would adversely impact the Western Grebe population. As expected, lipid content of carcasses increased significantly from October (15.5%) to February (28.8%).

Canadian Field-Naturalist↗
USGS1989

Breeding biology and habitat use of black ducks

Forested wetlands are Important habitats for black ducks nesting in the Northeast. Invertebrates, with their high protein content, are primary foods of females during egg laying and for rapidly growing ducklings. Beaver-created and modified wetlands provide excellent habitat for feeding as well as protective cover. As these wetlands age, their quality declines after 7-10 years, and waterfowl use diminishes. Wetland availability and quality should be considered when managing beaver.

Maine Agricultural Experiment Station Miscellaneou↗
USGS1997

Reproductive biology of the green turtle (Chelonia mydas) at Tern Island, French Frigate Shoals, Hawai`i

We monitored nesting of the green turtle (Chelonia mydas Linnaeus) on Tern Island, French Frigate Shoals, in the Northwestern Hawaiian Islands from 1986 through 1991. Egg oviposition occurred between 26 April and 20 October. Nesting peaked between mid-June and early August. Hatchlings emerged between mid-August and early October. Mean incubation period was 66.0 (range 53-97) days. Mean clutch size was 92.4 (range 33-150) eggs. Mean hatching success was 78.6% when averaged over success of individual nests and 81.1% when calculated as percentage of total number of eggs. Natural hatchling emergence was 71.1%, based on percentage of total number of eggs. Live and dead hatchlings were found when nests were excavated and accounted for 10.0% of the eggs. Incubation periods tended to be longer in early and later portions of the season than in midseason, and incubation periods tended to decrease the farther inland the nest was situated from the high tide line. Maximum hatching success occurred at an incubation length of 66.7 days. Other trends indicated that nesting peaked near 5 July when conditions produced a near optimal incubation period for yielding maximum hatching success.

Pacific Science↗
USGS1984

Breeding biology of the blue-gray noddy

Blue-gray Noddies, the smallest marine terns, are similar in many respects to all tropical terns in Hawaii: single-egg clutches are laid, growth and development take about 7 weeks, breeding is colonial. Its small size results in eggs that comprise over 27% of adult body weight, compared to 15-20% for most marine terns (Langham 1983). Blue-gray Noddies are widespread in the tropical Pacific, but populations are generally small. This may be the result of its inshore feeding habits and the fact that it is a resident species (Diamond 1978). However, populations in the Hawaiian Archipelago are probably limited by the availability of suitable nest sites in cliffs or rocky outcrops, not food supplies..... Food habits in Hawaii confirm the unique dependence of this species on sea-striders but consumption may be seasonal Blue-gray Noddies take the smallest prey of any seabird in Hawaii and may feed on a lower trophic level..... The Hawaiian population is apparently heavier and produces larger eggs than Blue-gray Noddies elsewhere in the Pacific. This conforms with the general proposition that Hawaiian seabirds are larger than those in the central Pacific (Harrison et al. 1983). The Hawaiian population also has a more predictable breeding season than those farther south.This may be due to a greater seasonality of food supply, but the factors that control the timing of breeding are not clear. There does not appear to be any competition for nest sites with other seabirds.....Our information on growth and development will enable future investigators to estimate the ages of chicks during brief visits to Blue-gray Noddy colonies. This will facilitate programs that are designed to monitor the basic health of seabird populations and to detect changes from baseline that may result from human activities or oceanographic conditions.

Journal of Field Ornithology↗
USGS1998

Breeding biology of Acadian flycatchers in a bottomland hardwood forest

From 1993-1995, we located and monitored 601 Acadian Flycatcher (Empidonax virescens) nests in a large contiguous tract of bottomland hardwood forest on the White River National Wildlife Refuge, Arkansas. Annual reproductive success was significantly different among years; ranging from 10-25% (Mayfield estimate) over the three years of the study. There was no significant difference in nest success among study plots, with nesting success showing a trend of increasing late in the breeding season. Clutch size for non-parasitized nests averaged 2.9 ? 0.02 (SE) eggs with a mode of 3. Rates of Brown-headed Cowbird (Molothrus ater) parasitism were low (21%), accounting for 7% of all nest failures. However, parasitism by cowbirds resulted in a reduction of clutch size for nests initiated early (i.e., first nests and replacements) in the breeding season. Predation was the leading cause of nest failures, accounting for 75% of all failures. Snakes and avian predators were thought to be the leading cause of nest failures. Although additional factors must be investigated, preliminary results indicate that nest predation is a major influence on this population, despite the size of the forest tract.

The Wilson Bulletin↗