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Northern Prairie Wildlife Research Center

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Waterfowl Production on the Woodworth Station
in South-central North Dakota, 1965-1981


Age when found - Number of eggs plus incubation stage in days. (Assume that one egg is laid each day)

Brood A brood was indicated and tabulated when an adult hen was accompanied by one or more flightless ducklings of age-class I-III or by the presence of a hen actively engaged in distraction displays (i.e., a broody hen)

Canopy cover The more or less continuous cover of branches and foliage formed by the collective crowns of shrubs, forbs, and grasses. Also the top concealment over a nest

Cool-season grasses Grasses that initiate and do most of their growing during the cool seasons of the year when temperatures vary from 15° to 30°C (60° to 85°F), includes smooth brome, Kentucky bluegrass and needle-and-thread grass

Cover edge The zone where plant communities meet or where successional stages or vegetative conditions within plant communities come together

Cover height Generally, the average maximum height of leafy cover of grasses, forbs and shorter shrubs

Cropland Areas that are planted to grain or row crops, or that are plowed and left fallow. Usually these areas receive some tillage each year

Dabblers or dabbling ducks Mallard, gadwall, American wigeon, blue-winged teal, green-winged teal, northern shoveler, northern pintail and wood duck. These birds have surface dabbling feeding habits as opposed to divers

Depredation The art or instance of robbing, plundering, or laying waste to a nest or clutch

Divers or diving ducks Canvasback, redhead, lesser scaup, ring-necked duck, and ruddy duck. These birds dive below the water surface to feed as opposed to dabblers

Duck pair A group of one or more adult ducks that were recognized as indicating a nesting pair. Indicated pairs were partitioned for final tabulation: segregated pairs and lone drakes were tabulated for both dabblers and divers, lone hens were tabulated only for divers and only when males were not nearby, and male groups and mixed groups of males and females were tabulated for groups up to five with the exception of northern shovelers and American wigeon for which only lone males and pairs are counted (Hammond 1969)

Emergent vegetation Plants rooted in soil with their lower portions submersed, but with most of their photosynthetic tissues above water, such as cattail or bulrush

Exposure days The number of days a clutch of eggs is under observation and vulnerable to loss to predators or other decimating factors

Full clutch Clutch size of incubated nests that have no history of destroyed or missing eggs

Grassland Areas vegetated with various mixtures of grasses, forbs, and short woody species

Grazed habitat An area that was purposely grazed with domestic livestock at some time during a calendar year

Hayland Areas that have been plowed and seeded to mixtures of grasses or legumes for forage production and that are hayed annually

Herbaceous plants Plants having little or no woody tissue. Portions of perennial herbaceous plants above ground die back each year and are replaced by new growth

Idled habitat An area that was not been burned, grazed, or cultivated during a calendar year and that has a continuous stand of the current year's plant growth or residual vegetation present

Lodged vegetation Vegetation, alive or dead, that has been knocked down by some force

Mayfield method for computing nest success A method that uses the interval during which a nest is under observation and exposed to decimating factors

Native prairie Natural grassland that has never been tilled and most of which is classified as mixed-grass prairie consisting of a mixture of short, medium and tall grasses and forbs

Nest A scrape or bowl containing one or more eggs. The terms "nest" and "clutch" are often used interchangeably in this and other duck nesting study reports. Only nests tended by hens (not destroyed or abandoned) when found are used to compute nest success by the methods described

Nest fate The success or failure of a nesting attempt

Nest site Refers to the vegetation, soils, and other materials within a one meter circle centering on the nest scrape (bowl) and clutch

Nest site concealment Vegetation cover offering top (canopy) or side (surrounding) concealment of a nest

Nest success The probability that a nesting attempt will result in the production of one or more ducklings, as opposed to hen success-the probability that a hen will succeed in hatching at least one duckling in one or more nesting attempts

Nesting period The interval per year from the day the first egg was laid until the day the last egg was hatched for the population as a whole

Perennial A plant having a life span of more than two years

Predation Occurs when any organism kills an other organism for food (e.g., a red fox kills a hen or eats some duck eggs)

Prescribed burning Deliberately burning a stand of grass or other vegetation to achieve management objectives

Residual cover The standing or lodged, dead portion of vegetation from the previous growing season

Seasonal wetland An area where surface water is present for extended periods, especially early in the growing season. In most years, surface water is absent by the end of the season. When surface water is absent, however, the water table is often near the land surface

Seeded cover Areas that are planted to mixtures of grasses and legumes for producing wild life cover or for stabilizing soil under land retirement programs

Semi-permanent wetland An area where surface water persists throughout the growing season in most years. When surface water is absent, the water table is usually at or very near the land surface

Temporary wetland An area where surface water is present for brief periods during the growing season. The water table usually lies well below the soil surface for most of the year

Terminated nests Nests, successful or unsuccessful, no longer tended by a hen

Traditional method of computing nest success The number of nests in which one or more eggs hatched divided by the total number of nests of known fate that were found; reported as apparent nest success. Estimates by this method are almost always extremely biased

Upland nesting ducks Mallard, gadwall, American wigeon, blue-winged teal, green winged teal, northern shoveler, northern pintail and lesser scaup. As opposed to those species which normally nest over water

Vegetation physiognomy A combination of the external appearance of vegetation, its vertical structure, and the life forms of its dominant taxa

Visual obstruction The 100% horizontal obstruction of the vegetation as read on a 5 cm square cover pole from a distance of 4 m and a sighting height of 1 m

Warm-season grasses Grasses that do most of their growing during late spring and summer when temperatures reach or exceed 29°C, includes big bluestem, little bluestem, and switch grass

Wet basin A wetland was considered to be wet when a basin was at least 5% inundated and the water was 2.5 cm or more deep

Wetland complex A collection of wetlands of varying sizes, water depths, and plant communities, all in close proximity

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