2007 to 8 May 2008) of beavers (n = 53) from beaver claw samples, Voyageurs National Park, Minnesota Summer Winter Mean SD Mean SD Isotopic signature ([per thousand]) [delta][sup.13]C -23.96 0.96 -23.75 1.04 [delta][sup.15]N 3.23 * 1.39 2.99 * 1.48 % diet Floating leaf 32.7 * 30.1 39.1 * 32.4 Emergent 23.4 * 34.6 16.1 * 36.0 Terrestrial 43.9 21.7 44.8 24.2 * Different between seasons (P < 0.05) TABLE 2.--Mean
beaver body mass, tail area (length X width) and tail thickness by age class, Voyageurs National Park, Minnesota, Apr.-May 2008 and Sept.-Oct.