James F. Bendell

Removal and Repopulation of Blue Grouse in a Declining Population

One hundred seven adult and yearling blue grouse (DendragaptAs obscurus) of both sexes were shot from an area of 900 acres near Middle Quinsam Lake, Vancouver Island, in the spring of 1970. The area was virtually emptied. In 1971, about 90 percent of the population on the removal area was replaced, mostly by yearling males and females, in an equal sex ratio. The control population was essentially unchanged in density, sex ratio, and age structure. The ingress of yearlings did not reduce the number of yearlings in the breeding populations on the control and surrounding areas. The main conclusion is that established or resident adult and yearling grouse interacted with yearlings to regulate yearling recruitment, and, in turn, to regulate the level of the breeding population. This interaction apparently happened in the early spring and on the summer range. Yearlings not recruited to the breeding population were surplus and disappeared. This process of population regulation occurred in the sparse and declining population at Middle Quinsam Lake and in a nearby dense and expanding population. It also operated in the sparse and declining population when this population was dense and stable. Hence, the process seems general in blue grouse, and perhaps also in other animal populations. Within broad limits, ^ve cannot correlate the ordinary variables of the environment, including the quality of food, with the regulatory process and the density of breeding grouse. The behavior of grouse in relation to each other and the causes of this behavior may be most relevant to population regulation and density. Future work should concentrate on when, how, and why some yearlings become established in the breeding population while others are excluded. parently occurs in early spring. Residents are adult and yearling breeding males and females and recruited yearling males (Bendell and Elliott 1987). Adults are approximately 2 years of age and older; yearlings are approximately 1 year old. They can be separated by features of plumage and weight (Bendell 1955a, Boag 1965).

Nest cooling and recess length of incubating spruce grouse

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Observations on Food Habits of Incubating Female Blue Grouse

Few data are available concerning foods eaten by incubating birds. We know of only two such references to tetraonids in North America, each of which deals with observations on use of feeding sites by two birds only (Schladweiler, J. Wildl. Mgmt. 32:426428, 1968; Pendergast and Boag, J. Wildl. Mgmt. 34: 605-611, 1970). Our data too are limited, consisting of crop samples from 19 incubating female Blue Grouse (Dendragapus obscurus) collected on Vancouver Island, British Columbia, in the summer of 1962. Nevertheless, these birds were taken from two structurally different habitats and give some insight into the range of foods acceptable to incubating Blue Grouse over a relatively short distance, the study areas being only 30 airline miles apart. The areas from which our birds were collected are Comox Burn (10 birds), near Courtenay, and Middle Quinsam (9 birds), near Campbell River. Comox Burn was swept by wildfire in September 1961; thus, birds here were collected from an area in the first growing season following burning. New plant growth was mainly from seeds or rootstocks that survived the fire. In contrast, about one-third of Middle Quinsam was burned by wildfire in 1938 and the other two-thirds in 1951. Succession was well advanced by 1962 and structure of the habitat and availability of plants were very different than at Comox Burn (Zwickel and Bendell, Proc. XV Int. Ornithol. Congr., In Press, 1972).