Seasonal changes in habitat use by Maine spruce grouse

Abstract

Seasonal change in habitats used by spruce grouse (Dendragapus canadensis) in eastern Maine was studied from spring 1981 until autumn 1983. Forest composition averaged 88 and 90% conifer tree species for males and females, respectively. Red spruce (Picea rubens) and balsam fir (Abies balsamea) were the dominant trees present in all habitats at all seasons. Forest density of habitats used by grouse differed significantly by season and sex. During winter males and females used conifer stands that were denser than random plots. During spring and summer females used sites that were less dense than those used by males and had a more open canopy and more ground vegetation. Both sexes showed seasonal changes in the proportion of time observed in trees. By midsummer, males and nonbrood females exhibited a strong selection for larch (Larix laricina) trees. During autumn both sexes moved to habitats with an increased proportion of larch and were found in these trees greater than 75% of the time Larch needles were considered an important transition food to the winter diet of conifer needles.