Publications

Intensity and chronology of molt in 10 feather groups (head, neck, breast, belly, back, rump, side, scapular, tertial, and tail) were measured using percentages of developing feathers (pinfeathers) converted to molt scores (0-100) in samples plucked monthly from northern pintails (Anas acuta) collected by shooting from August through March 1980-82 in the Sacramento Valley, California...

Abstract has not been submitted

A stochastic model of mallard (Anas platyrhynchos) productivity has been developed over a 10-year period and successfully applied to several management questions. Here we review the model and describe some recent uses and improvements that increase its realism and applicability, including naturally occurring changes in wetland habitat, catastrophic weather events, and the migrational...

No abstract available.

Post-fledging activities of 18 Ferruginous Hawks (Buteo regalis) were studied in southcentral North Dakota during July and August 1979. The post-fledging period ranged from 10 to 40 d (mean = 23.1 d; N = 16). Haylands and native prairie grasslands were the principal land use types utilized by fledglings and adults. Mortality of young during post-fledging was 11% (N = 2).

Abstract has not been submitted

We determined drainage rates for wetlands in North and South Dakota with U.S. Fish and Wildlife Service 20-year easements, during (1961-1980) and after (1981-1984) contract protection. Average annual drainage rates were 10 times higher during the four postcontract years than during the 20 contract years on the same tracts of land. Twenty-year easements only delayed wetland drainage, and...

Seasonal survival of 109 adult female mallards (Anas platyrhynchos) fitted with radio transmitters was evaluated in northcentral Minnesota during 1968-74. Survival rates for the 169-day breeding and postbreeding period were: 1.0 during nest initiation (36 days), 0.798 during incubation (28 days), 0.943 during brood rearing (51 days), 0.947 during molt (26 days), and 1.0 during...

Literature on the effects of fire and grazing on the wetlands used by breeding prairie waterfowl is reviewed. Both dabbling and diving ducks and their broods prefer wetlands with openings in the marsh canopy. Decreased use is commonly associated with decreased habitat heterogeneity caused by tall, robust hydrophytes such as Typha spp. and other species adapted to form monotypes in the...

A Lipid Index, the ratio of fat to fat-free dry weight, is proposed as a measure of fat stores in birds. The estimation of the index from field measurements of live birds is illustrated with data on the sandhill crane (Grus canadensis) and greater white-fronted goose (Anser albifrons). Of the various methods of assessing fat stores, lipid extraction is the most accurate but also the most...

The mark-recapture method for estimating striped skunk (Mephitis mephitis) abundance was evaluated by systematically livetrapping a radio-equipped population on a 31.4-km2 study area in North Dakota during late April of 1977 and 1978. The study population was 10 females and 13 males in 1977 and 20 females and 8 males in 1978. Skunks were almost exclusively nocturnal. Males traveled...

The need for accurate information in modelling depends on the objectives of the effort, but trustworthy data are essential for a model intended for use in the management of natural resources. This point is illustrated by referring to a recently published model of canvasback ducks. We demonstrate that several key assumptions are not supported by biological evidence, and that inferences...