Search USGS⌕ Search

Geology topics

C.W. Dane

Publications and source records attributed to C.W. Dane.

7 recordsLinked to original sources
USGS1979

Age determination of mallards

A technique for distinguishing adult from yearling wild mallards ( Anas platyrhynchos ), from late winter through the nesting season, was developed by applying discriminant analysis procedures to selected wing feather characters of 126 yearlings and 76 adults (2-year-olds) hand-reared from wild eggs during 1974, 1975, and 1977. Average values for feather characters generally increased as the birds advanced from yearlings to adults. Black-white surface area of greater secondary covert 2 was the single most reliable aging character identified during the study. The error rate was lowest in females (3%) when discriminant functions were used with measurements of primary 1 weight and black-white area of greater secondary covert 2 and in males (9%) when the functions were used with black-white area of greater secondary coverts 1, 2, and 3. Methodology precludes aging of birds in the field during capture operations.

North Dakota↗
USGS1976

Plasma luteinizing hormone and the development of ovarian follicles after loss of clutch in female mallards (Anas platyrhynchos)

The plasma level of LH and the extent of development of ovarian follicles were analyzed in incubating female Mallards. In both wild and game-farm stock, incubation was associated with a significant decline in plasma levels of LH from those of laying females. Within 1 day after removal of eggs, LH levels had increased to levels indistinguishable from those of laying females. The mean diameter of the largest follicle in wild females on the tenth day of incubation was 5.3 mm; it was 5.2 mm in game-farm stock at the same stage. Three days following removal of eggs, the mean of the largest follicles of wild-stock hens had increased to 14.0 mm and those of game-farm stock to 12.7 mm.

General and Comparative Endocrinology↗
USGS1975

Age determination of female redhead ducks

Eighty-seven fall-collected wings from female redhead ducks ( Aythya americana ) were assigned to the adult or juvenile group based on 'tertial' and 'tertial covert' shape and wear. To obtain spring age-related characters from these fall-collected groupings, we considered parameters of flight feathers retained until after the first breeding season. Parameters measured included: markings on and width of greater secondary coverts, and length, weight, and diameter of primary feathers. The best age categorization was obtained with discriminant analysis based on a combination of the most accurately measured parameters. This analysis, applied to 81 wings with complete measurements, resulted in only 1 being incorrectly aged and 3 placed in a questionable category. Discriminant functions used with covert markings and the three 5th primary parameters were applied to 30 known-age juvenile, hand-reared redhead females, 28 were correctly aged, none was incorrectly aged, and only 2 were placed in the questionable category.

Journal of Wildlife Management↗
USGS1968

Age determination of blue-winged teal

Primary feather length, markings on the greater secondary coverts, and the degree of bill spotting were evaluated as characters for use in the spring to distinguish first-year, blue-winged teal ( Anas discors ) females from older ones. The length of the 10th primary feather did not prove suitable to separate different aged females. Extreme primary lengths might be used to determine the age of some males. In females that have been through a postnuptial molt the greater secondary coverts have a more symmetrical, and more acutely angled, white, inverted 'V'-marking. Any female with a 'V' subjectively classified as good has gone through at least one postnuptial molt, and a female with no sign of a 'V' on the coverts is a juvenile or yearling before her first postnuptial molt. By measuring the longest bill spot on the upper mandible of each known-age female, it was possible to determine the age of some female teal. Because the spots fade during the breeding season, no lower size limit could be set to delineate first-year females at that time of year, but any nest-trapped hen with a spot longer than 10 mm was considered to be older than 1 year. Upper and lower limits were also established to distinguish some yearlings and 2-year-olds in the fall.

Journal of Wildlife Management↗
USGS1966

Some aspects of breeding biology of the blue-winged teal

The Blue-winged Teal ( Anas discors ) was the subject of one of the first publications dealing with the breeding biology of a species of North American waterfowl (Bennett, 1938). Recent studies of the nesting chronology, clutch size, and incubation period of this species include the works of Hochbaum (1944), Sowls (1955), and Glover (1956). The present paper supplements information on these aspects of breeding biology. Field work was done during the summers of 1961, 1962, and 1963 at the Delta Waterfowl Research Station (15 miles north of Portage la Prairie, Manitoba) which is adjacent to the Delta marsh at the south edge of Lake Manitoba. The climate in the area is subhumid. The mean annual temperature is 45.3°F and the annual precipitation is 20.1 inches at Winnipeg (60 miles ESE of Delta). The spring warming trend is variable and influences the time of spring arrival and the start of nesting of waterfowl (Sowls, 1955) and, as will be shown, the temperature may also influence the nesting chronology once a species has begun to nest. The daily mean temperatures and the daily lows at Winnipeg for the springs of 192 and 1963 are graphed in Figures 1 and 2. Daily records kept by nan Multer at Delta show that the temperatures there are similar to those at Winnipeg.

The Auk↗
USGS1964

Numbered nasal discs for waterfowl

Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal ( Anas discors ) with 5/8-inch discs, and canvasback ( Aythya valisineria ) and redhead ( A. americana ) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.

Journal of Wildlife Management↗