Date of Award

5-1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

I studied gray partridge (Perdix perdix) ecology in north-central North Dakota during 1985-87. The primary goals of this study were to identify habitats important to gray partridge survival and nesting, and to provide baseline data on partridge ecology in North Dakota. I captured and radio-tagged 100 gray partridge, mainly during winter. Individuals were tracked by a vehicle-mounted telemetry system until August of each year. Home ranges, movements, habitat use, and survival were calculated by using the telemetry locations. Winter home ranges averaged 117 ha, and were larger than previously reported in North America. Important habitats used by radio-tagged partridge during winter were cereal grains, sunflowers, and farmstead/wooded areas. Differences in habitat use were noted among years, dates, and snow depth. Roadside observations of partridge habitat did not accurately reflect actual use by partridge during winter. Capturing and radio-tagging gray partridge during winter negatively affected short-term survival. Body weight at time of capture was the best predictor of winter and spring survival. Survival of males was lower than that of females during both winter and spring. Overall survival from capture to the beginning of the nesting season was 50%. The major cause of mortality during these seasons was predation by raptors, mainly the great horned owl (Bubo virginianus). Roadsides were the most important nesting habitat. The best predictor of nest site availability in roadsides was presence of unmowed vegetation from the previous growing season. Available nesting cover was lower than in other areas. Home ranges and movements were smaller among partridge with young broods (0-2 weeks), than home ranges of radio-tagged partridge unaccompanied by broods. Young broods used crop fields, roadsides, shelterbelts, and idle areas whereas failed breeders used crop fields and fallow fields during summer. Gray partridge in North Dakota survive in intensively farmed areas by using annual crop fields. My study suggests that population levels are mainly influenced by limited nesting cover and adult mortality, rather than brood survival as has been found elsewhere.

Download

Included in

Psychology Commons

Share

COinS