Horsehair fungus, Marasmius androsaceus, used as nest lining by birds of the subalpine spruce-fir community in the northeastern United States

Abstract

We examined 54 nests of 40 species on Mt. Mansfield and Mt. Equinox, Vermont and Plateau Mountain, New York in the subalpine Red Spruce (Picea rubens) - Balsam Fir (Abies balsamea) forest bird community in the northeastern United States in 1994 and 1995. Forty-six nexts (85%) were found to contain fine, black, hair-like strands as lining material. This material was defined as the rhizomorphs of Horsehair Fungis (Marasmius androsaceus) and represents the first documented use of this material by North American breeding bird species. We believe that many earlier descriptions of nest lining materials used by boreal and subalpine bird species may refer to mis- identified Horsehair Fungus. Our finding that 85% of nests in montane spruce- fir forests of the northeastern United States contained copius amounts of rhizomorphs suggests that material is an integral component of nest construction in this habitat.