Production in spruce grouse and its relationship to environmental factors and population parameters

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Abstract
The extent to which a relationship existed between selected environmental and population parameters and annual production in a population of spruce grouse (Dendragapus canadensis franklinii) was investigated through correlation analysis of data spanning 16 years. Production of young grouse varied between 0.0 and 1.4 young, aged 4 or more weeks, per resident female over the period of this study. There was no evidence that differences in annual productivity were related to variation (maximum of 17 days) in the onset of reproduction, a function of spring temperatures. Nevertheless, weather conditions during incubation and the immediate posthatch period did exhibit a significant correlation with productivity: cold, wet conditions during incubation were associated with years of poor productivity, whereas the same conditions during the immediate posthatch period were associated with years of good survival of young (at least to 19 days of age). Clutch and brood sizes of yearlings were smaller than those of adults; hence, production could be influenced by the proportion of the population in each age category. An inverse relationship between the density of resident females in spring and their annual production, believed to be important in this population, was reexamined with data from an additional 6 years. The relationship, although still inverse, was no longer significant.