Publications

A 5-year investigation of factors influencing the selection of foods consumed by blue-winged teals (Anas discors) during the breeding season in the glaciated prairie region of south-central North Dakota showed that birds first arriving on the breeding grounds consumed a diet consisting of 45 percent invertebrates. The proportion of animal foods in the diet increased to 95 percent at the...

Food habits of breeding pintails (Anas acuta) were studied relative to sex, land use, and reproductive condition during the spring and summer of 1969, 1970, and 1971 in eastern North Dakota. Hens and drakes, respectively, consumed 79.2 percent and 30.0 percent animal matter on nontilled wetlands and consumed 16.6 percent and 1.1 percent animal matter on tilled wetlands. Aquatic dipterans

Duck nesting was studied during 1971 in north-central South Dakota under four conditions: in idle, five or six year old fields of domestic grass-legume mixtures in an area where predators including the red fox (Vulpes fulva), raccoon (Procyon lotor), striped skunk (Mephitis mephitis), and badger (Taxidea taxus) were (1) reduced and (2) not reduced. Nesting was also studied in tracts of...

The restrictive assumptions required by most available methods for estimating survival probabilities render them unsuitable for analyzing real banding data. A model is proposed which allows survival rates and recovery rates to vary with the calendar year, and also allows juveniles to have rates different from adults. In addition to survival rates and recovery rates, the differential...

A total of 211 wild, free-flying mallards (Anas platyrhynchos) and wood ducks (Aix sponsa) were equipped with breast-mounted radio packages during the breeding seasons of 1968-72. Known predation loss was 7.6 and 12.0 percent for mallards and wood ducks respectively, 60 percent occurred within 3 weeks of instrumentation. The highest predation rate for mallards was 0.0048 kills per...

Multispectral photography and ground truth were obtained on an area 12 miles (19.3 km) east of Bemidji, Minnesota, to identify and map wetlands less than 2 acres (0.8 hectare) in size, to map emergent vegetation in lakes, and to explore the feasibility of classifying vegetation from aerial photographs. Wetlands less than 2 acres in size were identified on photography taken in May 1971...

Abstract has not been submitted

Abstract has not been submitted

Food supply has been acknowledged as one of eight major external factors regulating the sexual cycles of birds (Marshall 1961). Several hypotheses have been advanced to explain the role of food supply as an ultimate factor regulating breeding (Marshall 1951; Lack 1954, 1968; Wynne-Edwards 1962; and others). Another potential influence of food is its being a proximate stimulus to breeding...

A high rate of homing to nest baskets by adult female mallards (Anas platyrhynchos) was observed in prairie potholes of North Dakota. One hundred and thirteen female mallards were caught on nest baskets, banded, and marked with nasal saddles. Forty-six percent homed at least once to nest baskets in the marshes where they were previously captured. Two-thirds of the returnees were observed...

Abstract has not been submitted

Abstract has not been submitted