Blue Grouse—Effects on, and Influences of, a Changing Forest

Abstract

Blue grouse (Dendragapus obscurus) may increase spectacularly in lowland Pacific coast forest that has been logged by clear-cutting. Locally, they may be used heavily by hunters, and more subtly, by nonconsumptive recreationsists. They can be sufficiently abundant to affect the survival of young conifers, the distribution of seeds and, perhaps, nutrient cycling. Blue grouse can represent a major component of the faunal biomass on a given area.Local populations of blue grouse change mainly as a result of forest management practices on lowland breeding ranges. Logging at higher elevations probably will not produce grouse in equivalent densities, and the implications of increased logging on winter range (at even higher elevations) are unknown.Current logging and silvicultural practices have both positive and negative effects on blue grouse. Newly logged lowlands are colonized rapidly by "surplus" grouse from nearby, established populations. They may persist in variable, but unpredictable, densities until forest canopy approaches 75% coverage. Populations decline due to non replacement of adults that die. Although clear-cutting often results in short-term, and occasionally large, increases in numbers, these persist for only about 25% or less of a planned rotation period. The productive period for occupancy by grouse may be shortened by early planting, planting everywhere, fertilization with urea, and by large, even-aged plantations. The productive period may be extended by delayed planting, a wider spacing within plantations, not planting sites of low timber productivity and, perhaps, by intensive thinning throughout the forest rotation, or cutting in small patches.An important key to continuous maintenance of breeding populations of blue grouse appears to be the presence of a well-developed and diverse understory. Alternatives to present clear-cutting practices that would leave a more open tree canopy would probably provide continuous production of grouse and many other species, albeit at a lower density than sometimes results from present programs. Experimental forests that can be manipulated in conjunction with long-term studies of the effects of these manipulations on wildlife are needed if we are to integrate forest - wildlife management practices fully. Keywords: blue grouse, Dendragapus obscurus, populations, clear-cut logging, silviculture, forest succession.