Geology topics

William J. Bleier

Publications and source records attributed to William J. Bleier.

4 recordsLinked to original sources

USGS2011

Land use and climate influences on waterbirds in the Prairie Potholes

Aim We examined the influences of regional climate and land‐use variables on mallard ( Anas platyrhynchos ), blue‐winged teal ( Anas discors ), ruddy duck ( Oxyura jamaicensis ) and pied‐billed grebe ( Podilymbus podiceps ) abundances to inform conservation planning in the Prairie Pothole Region of the United States. Location The US portion of Bird Conservation Region 11 (US‐BCR11, the Prairie Potholes), which encompasses six states within the United States: Montana, North Dakota, South Dakota, Nebraska, Minnesota and Iowa. Methods We used data from the North American Breeding Bird Survey (NABBS), the National Land Cover Data Set, and the National Climatic Data Center to model the effects of environmental variables on waterbird abundance. We evaluated land‐use covariates at three logarithmically related spatial scales (1000, 10,000 and 100,000 ha), and constructed hierarchical spatial count models a priori using information from published habitat associations. Model fitting was performed using a hierarchical modelling approach within a Bayesian framework. Results Models with the same variables expressed at different scales were often in the best model subset, indicating that the influence of spatial scale was small. Both land‐use and climate variables contributed strongly to predicting waterbird abundance in US‐BCR11. The strongest positive influences on waterbird abundance were the percentage of wetland area across all three spatial scales, herbaceous vegetation and precipitation variables. Other variables that we included in our models did not appear to influence waterbirds in this study. Main conclusions Understanding the relationships of waterbird abundance to climate and land use may allow us to make predictions of future distribution and abundance as environmental factors change. Additionally, results from this study can suggest locations where conservation and management efforts should be focused.

Iowa, Minnesota, Montana, Nebraska, North Dakota, ↗

USGS1994

Geographic variation in Yellow-headed Blackbirds from the northern Great Plains

We assessed geographic variability in morphology among Yellow-headed Blackbirds ( Xanthocephalus xanthocephalus ) collected from breeding populations in Minnesota, North Dakota, and South Dakota in the United States and Alberta, Manitoba, and Saskatchewan in Canada during spring. Both male and female Yellow-headed Blackbirds tended to be larger in the more northern breeding populations. Males collected in Manitoba and southeast Saskatchewan tended to be more like populations from the United States, whereas other populations in Saskatchewan and Alberta populations were morphologically similar to each other. For females, however, only the Manitoba population was similar to the U. S. populations, and the females from the southeastern Saskatchewan were similar to other Saskatchewan birds. Southeastern Saskatchewan appears to represent a transitional region between northwestern and southeastern breeding populations of Yellow-headed Blackbirds.

The Condor↗

USGS1992

Genetic variation in male Yellow-headed Blackbirds from the northern Great Plains

Electrophoretic differences at 15 presumptive loci were used to assess allelic frequencies, heterozygosities, and polymorphism for male Yellow-headed Blackbirds ( Xanthocephalus xanthocephalus ) collected in east-central Alberta, north-central North Dakota, and east-central South Dakota. Five loci were polymorphic and mean heterozygosities ranged from 0.119 to 0.133. Significant differences were detected among these geographic populations of Yellow-headed Blackbirds, primarily due to differences in the allelic frequencies of isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase. Differences detected were not sufficient to uniquely identify the geographic origin of Yellow-headed Blackbrids.

Canadian Journal of Zoology↗

USGS1991

Geographic and temporal variation in the diet of Yellow-headed Blackbirds

Yellow-headed Blackbirds ( Xanthocephalus xanthocephalus ) are presumed predators of sunflower ( Helianthus annuus ) in the northern Great Plains. Their esophageal contents varied temporally and among three provinces and three states in relation to regional agricultural bases but males contained more sunflower and small grains than females whereas females contained more weed seeds and insects than males. The diets of both sexes frequently included insects but insects comprised only a small proportion of the total dry weight of esophageal contents. In north-central North Dakota, sunflower represented about 50% of the esophageal contents of males in spring and fall but comprised less than 20% of the female diet. Small grains comprised about 25% of the female diet in all seasons and about 40% of summer diet of males. Insects represented about 50% of the diet of females until mid-summer when insects were largely replaced by weed seeds.

The Condor↗