A STUDY OF THE BLUE GROUSE (DENDRAGAPUS OBSCURUS (SAY)) ON VANCOUVER ISLAND, BRITISH COLUMBIA

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Abstract
A study was made of the summer habitat, seasonal movements, fluctuations in populations, population density, breeding cycle, and summer feeding habits of Dendragapus obscurus fuliginosus (Ridgway). During the summer the grouse were found mainly in the early stages of the developing second-growth forests following fire or logging. The birds descended to the lowlands in late March and early April. Most of the adult males returned to the uplands by the end of July, The females and broods left the lowlands by the end of September. There is evidence of several well-marked fluctuations in the numbers of blue grouse in British Columbia since 1904. A density of about.2 adults per acre was recorded in late June and early July. Nesting took place in May and the first young appeared early in June. After the first of July it was not uncommon to see two females with their intermingled broods feeding together. The summer foods of both adults and young were almost entirely vegetable. Grit was the main item in gizzards from birds collected before the middle of July but later it was largely replaced by hard seeds. The grouse were not observed to drink free water except in captivity. There is a rough parallelism between frequency of occurrence of the main items of food in the environment and the proportion of each occurring in the diet.