Geology topics

D.G. McAuley

Publications and source records attributed to D.G. McAuley.

39 records · Page 3Linked to original sources

USGS1985

An aerial photographic census of Chesapeake Bay and North Carolina canvasbacks

We used conventional 35-mm photography to conduct an aerial photographic census of canvasbacks ( Aythya valisineria ) throughout Chesapeake Bay (tidal Maryland and Virginia) and coastal North Carolina, 26-30 January 1981. Flock size and sex ratio characteristics were determined from examination of color transparencies of 165 canvasback flocks totaling over 95,000 birds. A sex ratio of 2.91 males/female was determined from 68,769 birds, 80% of the birds in 150 flocks. Sex ratio for the Atlantic Flyway was projected as 2.90 males/female. We recorded the greatest number of canvasbacks and the widest range of flock size in Maryland waters; the fewest canvasbacks and the smallest average flock size in Virginia; and the fewest but on average the largest flocks of canvasbacks in North Carolina. Sex ratio varied latitudinally in the flyway with a tendency for males to occupy more northern and females more southern latitudes in winter. Sex ratio (males/female) was highest in Maryland (3.98), slightly lower in Virginia (3.71), and lowest in North Carolina (1.70). Locally, sex ratio varied with flock size. In Chesapeake Bay, small flocks (<100 birds) had lower sex ratio (P < 0.05) than medium (100-1,000) or large (>1,000) flocks. By providing large- sample sex ratio information, as well as exact counts of birds, we conclude that low-level 35-mm aerial photography is the most efficient and accurate means of determining canvasback population status in eastern coastal habitats.

Maryland, North Carolina, Virginia↗

USGS1982

Woodcock brood ecology in Maine

Captures of 102 American woodcock (Philohela minor) broods, including 338 chicks, from 1977 to 1980 provided data on age-related production by breeding females and on growth and survival of chicks. Although broods of second-year females are smaller and hatch at slightly later dates and the growth of the chicks is slower than that of broods of after-second-year hens, we could detect no difference in survival of the chicks. Yearly variation in the sex ratio of fledged young was probably the result of selection for or against larger female chicks during different environmental conditions. Broodmates associate with each other throughout the summer, and there are differences in habitat preferences between young (1-5 days old) and older (> 5 days old) broods. Older broods prefer more open, mature forest stands with fewer trees per hectare.

Book chapter↗

USGS1982

Techniques for trapping, aging, and banding wintering canvasbacks

Techniques used to trap, band, and determine age of Canvasbacks during winter on Chesapeake Bay are presented. Canvasbacks were captured with welded-wire traps baited with corn. Two trap designs were used and traps and trapping techniques are described. Ducks were dipnetted from traps and held in modified poultry crates that provided seclusion and ventilation and allowed birds to dry unsoiled. Carney's (1964) wing plumage methodology was found most efficient in determining age of Canvasbacks during large-scale bandings. This technique was rapid and was easily taught to inexperienced personnel. In contrast, the cloacal technique could be performed efficiently only by experienced and skillful banders. Band wear was observed to vary widely on individual birds and rounding of bands was recognized as an important technique in extending band life. Bands were placed upside down on the tarsus so that wear along the upper edge would be less likely to destroy band numbers. In 5 winter seasons, over 17,000 Canvasbacks were captured. Mortality rate for the program was .3%.

Journal of Field Ornithology↗