Bland, J.D. 1997: Biogeography and conservation of blue grouse Dendragapus obscurus in California - Wildl. Biol. 3: 270.
Blue grouse Dendragapus obscurus habitat associations were conducted in California at two geographic scales: 3rd-order associations between hooting groups and forest composition in the Sierra Nevada Mountains, and 1st-order associations between blue grouse and major vegetation types throughout the state. Findings are discussed with respect to distribution, habitat requirements, and conservation status of insular blue grouse populations in California. A total of 104 km of potential habitat was surveyed at the perimeters of Lassen Volcanic, Yosemite, and Sequoia National Parks, and the number, density, and habitat associations of grouse were studied intensively on six selected hooting sites. A revised state range map was created by plotting 550 observation records on a 1:1,000,000 map and adjusting range limits to more closely correspond with observation records, major forest types, and elevation contours. Exploratory surveys indicated abundances of territorial male blue grouse from 0.2 to 1.5/km (0.3 - 0.4/100 ha). Spot-mapping indicated densities ranging within 7-37 ha/grouse, distances between nearest neighbours ranging from 50 to 615 metres, and a maximum group size of five individuals. Hooting sites were generally on the upper portions of west-facing slopes, usually near an open glade, and often within a few hundred metres of a ridge or plateau. Canopies were patchy and dominated by Abies and Pinus. Understory vegetation typically consisted of low (<1m) woody shrubs (Arctostaphylos, Castanopsis, Ceanothus, Ribes) interspersed with sparse grasses, herbs, and bare ground. Plotted observation records corresponded well with the distribution of CALVEG forest types. Potential insular populations were delineated in the southern North Coast Range, The Modoc Plateau, and in the White, Piute, Tehachapi, and northern Transverse ranges. Isolated Abies forests were identified at the core of most insular habitat.
Key words: blue grouse, California, conservation status, Dendragapus obscurus, distribution, habitat requirements, hooting groups
James D. Bland, 604 E. 11th Street, Davis, California 95616, USA