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The northern limit of the blue grosbeak's ( Guiraca caerulea ) breeding distribution occurs in southern North Dakota. Records of the blue grosbeak in North Dakota are uncommon. Here, I report my observation of a blue grosbeak at a site where the species was recorded 25 years earlier. A summary of the species' distribution and records in North Dakota are provided.
No abstract available.
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An active Northern Harrier, Circus cyaneus, nest containing Redhead, Aythya americana, eggs, found in an Alberta wetland, apparently represents the first record of a Redhead parasitizing a harrier.
Abstract has not been submitted
Native prairie areas on the Woodworth Station were sampled, classified, described, and mapped. Transect sites were selectively located along different soil moisture gradients. Data were collected from 292 plots using a modified Braun-Blanquet cover estimation technique. Trees and tall shrubs (over 2 m) were not sampled because they made up less than 1% of all cover. Eve vegetation classes were established based on growth forms. They were mixed grass, shrub, tall grass, broad-leaved forbs, and trees. Each class is divided into community types based on species composition. The mixed-grass class has blue grama, Kentucky bluegrass, and mixed native grasses. The shrub class is divided into low shrub, shrub grassland, and tall shrub. The tall-grass class includes little bluestem, big bluestem, bluestem Indian-grass, and prairie cordgrass. These results will provide baseline information for long-range plans on habitat management which are being developed for the Woodworth Station.
Abstract has not been submitted
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Winter distribution and abundance of raptors were monitored within the Platte and North Platte river valleys. Data were collected along 265 km of census routes along the Platte and North Platte rivers during the winters of 1978-1979 and 1979-1980. Observations recorded during the second winter involved less observation time and were at somewhat different periods. There were 1574 sightings of 15 species representing 3 raptor families. Number of raptors observed on 54 days from 15 November to 13 February 1978-1979 was 48.3 per 100 km. In 20 days of observation from 5 December to 6 March 1979-1980, 39.7 raptors were observed per 100 km. Small mammal indices were 21 and 12 captures per 1000 trap nights during November 1978 and 1979, respectively. Raptors were sighted most frequently in riverine habitat and least in pasture and tilled fields. American kestrels (Falco sparverius) (11.1 individuals/100 km), red-tailed hawks (Buteo jamaicensis) (9.9), and bald eagles (Haliaeetus leucocephalus) (9.6) were the most frequently sighted raptors. Northern harrier (Circus cyaneus), rough-legged hawk (B. lagopus), and prairie falcon (P. mexicanus) sightings were 3.4, 3.4, and 1.7, respectively. Nine species were seen at a frequency of less than 1.0 individuals/100 km. Improved foraging conditions throughout the region resulted in fewer raptors sighted in 1979-1980.
Abstract has not been submitted
Abstract has not been submitted
Franklin's Ground Squirrels (Spermophilus franklinii) preyed on eggs in 29 of 30 tests in which they were exposed to two Mallard (Anas platyrhynchos) or two Blue-winged Teal (A. discors) eggs and their discovery of eggs was confirmed. No Richardson's (S. richardsonii) or Thirteen-lined (S. tridecemlineatus) ground squirrels preyed on eggs in 104 and 54 similar tests, respectively. Franklin's Ground Squirrels exposed to clutches of six duck eggs placed in simulated nests preyed on all such clutches. Predation on simulated nests began soon after eggs were discovered, but predation of all eggs often took more than one day to complete.
Detailed study of radio-equipped individuals of the Striped Skunk (Mephitis mephitis) in a North Dakota population provided insight into possible mechanisms for spread of rabies during spring and summer. Annual recurrence rates of 138 skunks marked on a study area averaged 11% for adult males, 43% for adult females and 9% for kits. Population changes were from mortality (including rabies) and dispersal. Five instances of adult dispersal (four by males) were recorded; maximum straight-line distance was 119 km. Some males initiated dispersal in spring. Communal denning by adults occurred rarely after whelping began but resulted in intraspecific conflict. Evidence of intraspecific and interspecific strife leading to kit mortality and some adult mortality was found at dens of 9 of 40 litters studied.
Stomach contents of 70 red foxes (Vulpes vulpes) shot in east-central North Dakota during January 1982 and January 1983 were examined. Commercial sunflower seeds were the most frequently found food item, occurring each year in three-fourths of the stomachs and composing about half of the contents. The remainder of the diet was primarily mammals, but included birds, insects, amphibians, and refuse.
Grazed native prairie, unmanipulated native prairie, and planted alfalfa-wheatgrass habitats each supported prairie bird species unique to that habitat type. Comparisons of the three habitats, using community coefficients and overlap indices, showed that grazed and alfalfa-wheatgrass habitats supported the most dissimilar or unique bird communities. All three habitat types, or habitats with similar vegetation structure, must be incorporated in grassland management plans to support all members of the mixed-grass prairie bird community.