Food Habits and Preferences of Blue Grouse during Winter

Abstract

We determined winter food habits of blue grouse (Dendragapus obscurus) by observing radiomarked birds in the wild over 2 years. We used captive blue grouse to assess preference for, and voluntary intake and metabolizable energy (ME) of, Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), limber pine (P. flexilis, preference only), subalpine fir (Abies lasiocarpa), and Engelmann spruce (Picea engelmannii). Most (91%) feeding by wild birds was in Douglas-fir or lodgepole pine. Feeding was concentrated on younger needles in the upper canopy of older trees. Limber pine was browsed by some birds, but feeding was rarely observed in subalpine fir or Engelmann spruce. Preference rankings closely paralleled ME values: Douglas-fir (ME = 1.80 kcals/g) = lodgepole pine (1.72 kcals/g) > limber pine (ME not calculated) > subalpine fir (1.52 kcals/g) = Engelmann spruce (1.15 kcals/g). Captive birds preferred needles from mature Douglas-fir to needles from young trees, and 1-2 year-old needles of Douglas-fir to older needles. This selection was consistent with a strategy of maximizing intake of metabolizable energy while meeting nitrogen requirements. Although blue grouse preferred to eat needles of species from which they extracted the most energy, these needles were not clearly superior by conventional nutritional analyses.