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Results for “Transactions of the Northeast Section, The Wildlife Society”

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7 recordsLinked to original sources
USGS1987

Black duck-mallard interactions on breeding areas in Maine

Mallard (Anas platyrhynchos) pairs (2-4) and broods (1-2) have occurred sporadically each year during recent (1977-86) waterfowl investigations in Maine. State-wide brood counts (1956-1986) for 36 wetlands in Maine depict an average increase of 1-3 mallard broods. Broods occurred mostly on man-made impoundments. Numbers of mallards captured during banding (as a percentage of combined mallards, American black ducks [Anas rubripes] and hybrids) have increased from 4.3 to 28.7% in southern Maine, 3.6 to 9.1% in central Maine, and 0.5 to 2.6% in eastern Maine during the last 3 or 4 decades. The percentage of mallards captured in northern Maine in the last decade averaged 11.8%. The occurrence of mallard x black duck hybrids handled during pre-season banding has been variable among decades, but < 2.0% for all the banding sites. Mixed-species pairs, usually a male mallard and a female black duck have been recorded. . Survival of mallard ducklings to fledging (4/brood) approximates that of black ducks, but our sample of broods (N=7) was small. Paired, male, black ducks aggressively drove away intruding mallards and conspecifics. The role of mallard releases and small marsh construction is implicated in the establishment of the 657 mallard pairs estimated as breeding in Maine.

Transactions of the Northeast Section, The Wildlif↗
USGS1978

Biochemical identification of mallard-black duck hybrids through a breeding program and in nature

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, mallard or black duck crosses with hybrids were detectable as hybrids in only 11.5 - 22.6% of the progeny using serum proteins, and 22.6 - 38.8% using serum esterases. Concurrent with the breeding program, a field survey indicated hybrid frequencies ranging from 4% to 28%.

Transactions of the Northeast Section of the Wildl↗
USGS1980

Computer simulation models as tools for identifying research needs: A black duck population model

Existing data on the mortality and production rates of the black duck (Anas rubripes) were used to construct a WATFIV computer simulation model. The yearly cycle was divided into 8 phases: hunting, wintering, reproductive, molt, post-molt, and juvenile dispersal mortality, and production from original and renesting attempts. The program computes population changes for sex and age classes during each phase. After completion of a standard simulation run with all variable default values in effect, a sensitivity analysis was conducted by changing each of 50 input variables, 1 at a time, to assess the responsiveness of the model to changes in each variable. Thirteen variables resulted in a substantial change in population level. Adult mortality factors were important during hunting and wintering phases. All production and mortality associated with original nesting attempts were sensitive, as was juvenile dispersal mortality. By identifying those factors which invoke the greatest population change, and providing an indication of the accuracy required in estimating these factors, the model helps to identify those variables which would be most profitable topics for future research.

Transactions of the Northeast Section of the Wildl↗
USGS1980

Factors affecting waterfowl breeding density and productivity estimates in the Northeast

During 1977-79, information useful for making breeding pair and brood surveys was obtained while studying black duck (Anas rubripes) habitat selection and productivity in south-central Maine. Surveys should be initiated in relation to sunrise and sunset time. Morning versus evening counts, familiarity with the survey area, wetland dynamics of the study area, wetland surface water area, and allotment of relative survey effort are discussed as they affect the conduct and results of brood surveys.

Transactions of the Northeast Section of the Wildl↗