Publications

Submerged aquatic plant populations in the Susquehanna Flats of the Chesapeake Bay were followed for 18 years. An exotic species, eurasian water milfoil, Myriophyllum spicatum, increased dramatically from 1958 to 1962; at the same time the dominant native species declined. After 1962, milfoil populations declined and the native rooted aquatics gradually began to return to their former levels. In t

Spatial and temporal relationships among members of a raccoon (Procyon lotor) population were studied during spring and summer in east-central North Dakota during 1973–1975. Radio telemetry was used to locate 48 raccoons 6443 times. Livetrapping results and other observations suggested that most raccoons in the area were radio equipped; densities were estimated to be 0.5–1.0 resident/km2. Adult ma

Mobility and habitat use of raccoons (Procyon lotor) in an intensively farmed area of the prairie pothole region were studied during the waterfowl breeding seasons (April-July) of 1973-75. Over 5700 locations of 30 raccoons were analyzed. Movement patterns varied with sex, age, and reproductive status. Adult males moved regularly throughout slightly overlapping ranges that averaged 2560 ha. Yearli

Necropsies and observations of captive and radio-equipped individuals provided reproductive data from a raccoon population in the northern prairies. The mean parturition date of adult females was 8 May and the mean litter size was 4.8. Only two of the 14 yearling females examined prior to 1 July were pregnant; they had estimated parturition dates of 20 May and 22 June. Penes of most yearling males

Radio telemetry was used to locate 31 wood duck (Aix sponsa) nest cavity sites in 16 forest stands. Stands were of 2 types: (1) mature (mean = 107 years) northern hardwoods (10 nest sites), and (2) mature (mean = 68 years) quaking aspen (Populus tremuloides) (21 nest sites). Aspen was the most important cavity-producing tree used by wood ducks and accounted for 57 percent of 28 cavities inspected.

Abstract has not been submitted

Abstract has not been submitted

Wild and game-farm mallards (Anas platyrhynchos) raised in pure strain and mixed groups were tested for initial mate preference in a choice test. Female mallards showed no significant preference but males of either strain raised with females of their own strain significantly preferred female models of their own strain during the test. Males raised with females of the other strain merely showed att

Small islands constructed in prairie wetlands were attractive nesting sites for mallards (Anas platyrhynchos) and Canada geese (Branta canadensis). Nest densities of mallards on islands averaged 135 per ha compared to 0.03 per ha on adjacent upland habitats. Construction time averaged 2 hours per island and cost $50. No maintenance was required during the first 10 years.

Abstract has not been submitted

From 1974 to 1976, a breeding program was used to produce black duck-mallard hybrids for the evaluation of inheritance patterns of serum proteins and esterases. In addition to the initial crosses, a series of matings in 1975 and 1976 were designed to evaluate inheritance patterns in hybrid matings with either black duck or mallards. At the F1 level, hybrids were easily distinguished. However, mall

Nesting studies are used to assess the production of birds and to evaluate nesting habitats. Most such studies involve finding nests in a given area and subsequently determining the proportion that hatched. Unfortunately, the results are often biased by unrecognized differences in the probabilities of finding successful and unsuccessful nests. The observed hatch rates of 1,900 nests of blue-winged