Jenkins Stephen H
Department of Biology, University of Nevada, 89557, Reno, Nevada, USA.
Oecologia. 1979 Dec;44(1):112-116. doi: 10.1007/BF00346408.
Selection of trees for food by a colony of beavers in central Massachusetts was studied from September 1972 through April 1974. The beavers exhibited both seasonal and year-to-year differences in preference for certain genera. Pine was selected against during fall but not spring, and there was a switch in preference from birch during fall 1972 to oak and witch hazel in fall 1973. These differences may partly reflect greater seasonal stability in concentrations of stored nutrients in coniferous tree bark than in deciduous tree bark, and greater year-to-year stability in bark concentrations of stored nutrients in non-mast-seeding species than in mast-seeding species (1972 was a mast year for oaks in central Massachusetts).
1972年9月至1974年4月，对马萨诸塞州中部一群海狸选择食用树木的情况进行了研究。海狸在对某些属的偏好上表现出季节性和逐年差异。秋季不选择松树，但春季选择，并且偏好从1972年秋季的桦树转变为1973年秋季的橡树和金缕梅。这些差异可能部分反映出针叶树树皮中储存养分浓度的季节性稳定性高于落叶树树皮，以及非产籽大年树种树皮中储存养分浓度的逐年稳定性高于产籽大年树种（1972年是马萨诸塞州中部橡树的产籽大年）。
