The amount of cover, height, density and spatial arrangement of forbs, grasses and shrub species provides important cover for grassland nesting birds, to avoid predation on the land and from the air and to improve nesting success. Grazing of B.C. grasslands affects cover quality and availability for ground nesting birds. Threshold levels of cover resulting from grazing practices for grassland nesting birds has not been well defined in literature and is lacking for species found in B.C. and on B.C.?s grasslands. Data presented in this report is part of a larger long term study of the visual screening cover of B.C.?s grasslands available for both small mammals and grassland nesting birds in grazed and ungrazed ecosystems. Partners in this project include Environment Canada, Simon Fraser University, the Ministry of Environment, The Ministry of Forest and Range (FREP), the Grassland Conservation Council of B.C., the National Science and Engineering Council (NSERC), the Habitat Conservation trust Fund (HCTF), Thompson Rivers University and the OK Ranch. Bird species included in the evaluation are species that rely on grassland structure for nesting cover. Species studied include the Sharp-tailed Grouse (a blue-listed species), Meadowlark, and Savannah and Vesper sparrows. Almost all the nest sites found within the study areas had cover greater than the cover generally available in the area. All three bird species, Sharp-tailed Grouse, Meadowlark, and Vesper Sparrow, chose nest sites with lots of cover. Further research is necessary to determine the relationship between cover and nest cover in different grassland ecosystems under different grazing regimes across years. This will provide more information on the role of climate change, grazing and long term nest success as well as further test the use of digital photography for measuring cover.
Haddow, C.M., B. Bings. 2009. Monitoring Grassland Bird Nest Cover Using Digital Photography at Two Locations in the Cariboo Grasslands of British Columbia. Ministry of Environment