Winter Food Selection by Alaskan Spruce Grouse

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Abstract
In winter spruce grouse (Canachites canadensis) in Alaska [USA] feed on only the needles of black spruce (Picea mariana) and white spruce (P. glauca) trees. The birds prefer to feed in P. glauca trees rather than P. mariana, partly because the densely growing needles of P. mariana make feeding more difficult. P. mariana contains more crude fat than P. glauca, less ash and less protein in some habitats, any of which also may result in discrimination against P. mariana. Within P. glauca, the needles of trees that are selectively browsed are less dense and contain less crude fiber than the needles of unbrowsed trees. The foliage of browsed and unbrowsed P. glauca trees does not differ in crude protein (N .times. 6.25), soluble carbohydrates, P, K, Ca, Na, Fe, Mg, Mn, Cu, Zn, Sr, Ba, Al and B.