Population Of Blue Grouse Research Articles

Nesting parameters in a high density, declining population of blue grouse

Of four nesting parameters (clutch size, egg fertility, egg hatchability, and nesting success) in a population of blue grouse, Dendragapus obscurus fuliginosus, at Hardwicke Island, British Columbia, only clutch size differed between yearling and adult females. There was no difference among years for any of the parameters considered. This population declined from very high to moderate density during the studies reported here, and clutch size, egg fertility, and hatchability were significantly lower than reported for a more stable population (Comox Burn) in the same general region. Nesting success at Hardwicke Island, however, was higher than at Comox Burn. Collectively, the parameters examined do not, by themselves, explain the observed decline. Nevertheless, they suggest that the population at Hardwicke Island differed from that at Comox Burn in some fundamental aspects of reproduction that may be symptomatic of other factors possibly involved in its decline, e.g., the survival of chicks.

Pyramiding Behavior in the Inca Dove: Adaptive Aspects of Day-Night Differences

ENG, R. L. 1963. Observations on the breeding biology of male Sage Grouse. J. Wildl. Manage. 27: 841-846. HANNON, S. J., B. R. SIMARD, F. C. ZWICKEL, AND J. F. BENDELL. 1979. Differences in the gonadal cycles of adult and yearling Blue Grouse. Can. J. Zool. 57:1283-1289. JAMIESON, I. G. 1985. Behavior of yearling male Blue Grouse and its relation to delayed breeding. Wilson Bull. 97:71-77. JAMIESON, I. G., AND F. C. ZWICKEL. 1983. Spatial patterns of yearling male Blue Grouse and their relation to recruitment into the breeding population. Auk 100:653-657. LEWIS, R. A. 1981. Characteristics of persistent and transient territorial sites of male Blue Grouse. J. Wildl. Manage. 45:1048-1051. LEWIS, R.A. 1984a. Non-territorial adult males and breeding densities of Blue Grouse. Wilson Bull. 96:723-725. LEWIS, R. A. 1984b. Survival, behavior, use of territories, and breeding densities of male Blue Grouse in coastal British Columbia. Ph.D.diss., Univ. Alberta, Edmonton. LEWIS, R. A. 1985. Use of space by territorial male Blue Grouse. Wilson Bull. 97:97-101. LEWIS, R. A., AND F. C. ZWICKEL. 1980. Removal and replacement of male Blue Grouse on persistent and transient territorial sites. Can. J. Zool. 58:1417-1423. LEWIS, R. A., AND F. C. ZWICKEL. 1981. Differential use of territorial sites by male Blue Grouse. Condor 83:171-176. LEWIS, R. A., AND F. C. ZWICKEL. 1982. Survival and delayed breeding in male Blue Grouse. Can. J. Zool. 60:1881-1884. McNICHOLL, M. K. 1978. Behaviour and social orga ization in a population of Blue Grouse on Vancouver Island. Ph.D.diss., Univ. Alberta, Edmonton.

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

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.

Foods selected by blue grouse (Dendragapus obscurus fuliginosus)

The spring and summer diet was determined from 811 blue grouse crops collected from 1957 through 1966 near the town of Campbell River on Vancouver Island. Main foods eaten were conifer needles, broad-leaved vegetation, flowers, fruits, and invertebrates. More than 80% of the plant diet was from nine species. Most foods were selected and selection varied with season, sex, and age. In the spring, females apparently ate more broad-leaved plants than did males, and chicks up to approximately 3 weeks of age fed largely on invertebrates, mainly ants (Formicidae). We attempt to explain selection by relating known nutrients in plants and animals to their use as food. Selection may be partly explained by availability, nutrients, and the nutritional requirements of grouse. Nutrients apparently selected most frequently were ash and nitrogen. The diet of females in May and June seemed richer than that of males in ash, nitrogen, and magnesium. In June, chicks had a diet likely higher in nitrogen, phosphorus, and potassium but lower in carbohydrate, fat, and calcium when compared with adults. The diet of blue grouse compared with that recommended for some other grouse was possibly deficient in ash, phosphorus, and calcium. We postulate food on the summer range might limit populations of blue grouse by the amount of nitrogen and minerals, especially calcium, available to hens in spring and by a range of nutrients available to very young chicks.

Demography, behavior, and genetics of a colonizing population of blue grouse

The demography, behavior, and genetics of a population of blue grouse (Dendragapus obscurus) that colonized an area from which most grouse were removed were compared with those of grouse on a nearby control area. Population density increased on the removal area from 1971 to 1974 but remained essentially stable on the control area. Although there were some differences in survival and reproductive rates among years and between areas, none appeared related to the experimental removal and subsequent replacement by new founders.No consistent differences in potentially aggressive behavior were observed between birds in the two populations. Behavioral differences that occurred were likely related to differences in age structures of the two populations or to the synchronous settling of a cohort of mostly young birds on the experimental area.There was no excess of Ng (Birdsall, α., J. A. Redfield, and D. G. Cameron. White bands on starch gels stained for esterase activity; a new polymorphism. Biochem. Genet. 4: 655–658 (1970)) homozygotes among recruits to the experimental area, in contrast with Redfield's (Demography and genetics in colonizing populations of blue grouse (Dendragapus obscurus). Evolution, 27(4): 576–592 (1974)) report of such an excess among birds colonizing new habitat.The increase in the population on the experimental area compared with the control area must have resulted from an increased recruitment of yearlings. No clear evidence was found that this increase was related to qualitative differences between stocks on the two areas.

An experimental study of the behavior of blue grouse (Dendragapus obscurus). I. Differences between the founders from three populations

In 1970 the authors compared the behavior of two low-density populations of blue grouse (Dendragapus obscurus) with the behavior of a high-density population on Vancouver Island. They then introduced individuals from these populations onto four islands and compared the behavior of these founders in 1971 and 1972.One island received founders from all three populations, while the other three islands each received founders from a single population. Birds from two low-density populations were quite observable, and displayed frequently when approached by field workers, both at their capture sites on Vancouver Island and in different habitats on the release sites on islands. The high-density population was much less observable, and displayed less frequently than did the two low-density populations, both at the capture sites and on the release islands. Male founders from the low-density populations were more aggressive in interacting with their mirror image than were males from the high-density population. Male founders from the high-density population dispersed less from the release sites, had smaller territories, and settled closer together than did males from the two low-density populations. These findings are consistent with the view that animals have a form of behavior that spaces them out as numbers rise, and so prevents unlimited increase in numbers.

Comparative demography of increasing and stable populations of blue grouse (Dendragapus obscurus)

The demographic characteristics of an increasing population of blue grouse were studied from 1968 to 1971. Increasing populations of grouse had high reproductive rates and slightly higher than average mortality rates among females as compared to stable populations.

Population attributes of blue grouse in southwestern Alberta.

A population of blue grouse (Dendragapus obscurus) was studied over a 10-year period in southwestern Alberta. During this time a number of population attributes were documented. Density declined from a maximum of 47 adult males in 1955 to a minimum of 6 in 1964 on the 620-acre study area. Dispersion of adult male blue grouse on the breeding grounds was accomplished by establishing territories which averaged 1.5 ac. Adult females inhabited overlapping home ranges which averaged 43 ac in size. The age distribution among marked birds on the breeding grounds in May and June indicated 75% adult (2 years and older) and 25% subadult (1 year of age). Of the adults, approximately one-half were 2-year-olds with decreasing proportions in older age classes until none remained after they were 9 years old. Juveniles formed 40% of the fall population each year. The average hatch was 5.1 chicks per breeding female. Recruitment to the population has been inadequate to maintain numbers. Excessive mortality or dispersal rates must account for this. Minimum recorded loss of chicks during their first summer averaged 27%. Mortality rate of birds more than 1 year old averaged 56% per annum. Dispersal to other breeding ranges was recorded only in juvenile grouse.

Further Observations on the Breeding Behavior of a Blue Grouse Population in Montana

This paper presents observations made in 1958 and 1959 on the behavior of a forestdwelling population of Blue Grouse (Dendragapus obscurus richardsonii) in northwestern Montana. (See Blackford, 1958, for earlier observations.) New information was gathered on the following aspects of courtship and breeding biology: conduct of the sexes during the vernal altitudinal migration, arboreal hooting and display, wing notes and flight signals, pair formation, association of mated birds, and communal display.

DISEASE AS A CONTROL OF A POPULATION OF BLUE GROUSE, DENDRAGAPUS OBSCURUS FULIGINOSUS (RIDGWAY)

A population of blue grouse was studied on its summer range at Quinsam Lake, Vancouver Island, to determine the factors of importance in population control. The population is stable with a density of 0.40 adult males and 0.78 yearling and adult females to the acre. A life table is constructed on the basis of a stable population, the death of 80% of the chicks in the first three months after hatch, and the death of 31% of the adults each year, as calculated from banding returns. The survivorship curve is negatively "J"-shaped. Mortality rates appear constant and independent of age after the first year of life. Space, weather, food, predators, and disease are considered as factors capable of population control. Six parasites are new records in this host. Two of the six, Plagiorhynchus formosus and Dispharynx nasuta occur commonly and almost exclusively in the chicks, where they cause extreme damage to the tissues of the gut. It is concluded that parasitism by these helminths is an important mortality factor in the chicks and a major cause of population stability—an equilibrium between death in the older age classes and replacement by surviving young.