Publications

A wetland in central Arkansas was contaminated with polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and because the area was a major waterfowl habitat, we studied the effects of the contamination on nesting wood ducks (Aix sponsa) during 1988-90. Residues in wood duck eggs, based on toxicity equivalency factors (TEFs) for combined compounds, ranged from 0.2 to 611...

A new plasticine-filled leg band was developed for use in banding dayold ducklings. These bands permit inference about early survival that is not possible from banding of older young in standard operations. Two double-marking experiments with web tags and the new leg bands indicated a high retention rate for the leg bands. In contrast, several web tags were lost, permitting an analysis...

No abstract available.

Low annual survival of hatching-year (HY) females is a critical management concern for canvasbacks (Aythya valisineria), and may contribute substantially to reduced reproductive potential and the male-biased sex ratio of the species. To evaluate the contribution of mortality on a traditional wintering area to low annual survival, we estimated survival rates of HY female canvasbacks...

Phenacosaurus neblininus, new species, was discovered during the 1984-1985 expedition to Cerro de la Neblina on the Venezuelan-Brazilian border. It was found at several highland camps (> 1600 m) but seems unaccountably rare, with only six specimens collected. The closest relative of this lizard may be another new species (Williams et al., MS) known from a single specimen from Chimanta...

Transmission risk of Lyme disease at a site can be estimated using the probability of exposure (P1 = probability of being bitten by at least one infected tick); P1 =1 - (1 - kt)n, where n = number of tick bites per person and kt = spirochete prevalence in questing ticks. This probability is more directly related to the likelihood of acquiring Lyme disease than the standard measure of...

Northern pintails (Anas acuta) exist as a single circumpolar breeding population but display weak fidelity to given breeding sites. If fidelity to wintering areas is strong, management on wintering grounds may allow local winter populations to increase. Thus, I delineated reference areas for wintering areas based on recovery data for pintails banded during the winter (Dec-Feb) in the...

From 1950 through 1988, the continental breeding population of northern pintails (Anas acuta) varied from 2.0 million to 9.9 million. Because pintails have high fidelity to certain wintering grounds along coasts and large bodies of water, management on these wintering areas may increase population size if changes in winter survival rate are related to changes in population size. I used...

No abstract available.

No abstract available.

A study of wood ducks (Aix sponsa) was conducted along the Coeur d'Alene River system in northern Idaho in 1986 and 1987. Most of this area has been subjected to severe contamination from lead and other metals from mining and smelting since the 1880s. In 1986, a preliminary study of wood duck nesting was conducted in the contaminated area; incubating hens captured in nest boxes were bled...

We measured nipple sizes of 29 captive wolves (Canis lupus), of known breeding histories, throughout the year and tested distinctions among various known breeding statuses of 20 wild wolves examined in northeastern Minnesota from May through September. For ca. 8 mo of the year only breeders and nonbreeders can be classified. Distinctions between current and former breeders were not...