Hulbert Ian A, Iason Glenn R, Mayes Robert W
Department of Zoology, University of Aberdeen, Tillydrone Avenue, AB24 2TZ, Aberdeen, Scotland.
The Macaulay Land Use Research Institute, AB15 8QH, Craigiebuckler, Aberdeen, Scotland.
Oecologia. 2001 Oct;129(2):197-205. doi: 10.1007/s004420100725. Epub 2001 Oct 1.
Herbivores with an intermediate feeding strategy either vary their diet between a grazing (bulk roughage feeders) or browsing (concentrate selectors) strategy on a seasonal basis or select a mixed diet at any one time. The underlying ecological causes of the seasonal dietary shift in a small non-ruminant intermediate feeder - the mountain or arctic hare (Lepus timidus L.) were determined. Diet composition and selection relative to availability were investigated for 41 individual free-ranging mountain hares (of which 18 female hares were radio-collared) occupying an upland mosaic landscape in north-east Scotland. Diet composition was determined using faecal n-alkane analysis. Radio-collared hares were designated as pasture, woodland or moorland hares according to the habitat that predominated their home-range. In common with previous studies, mountain hares switched from a browse-dominated diet during winter to a Gramineae-dominated diet in summer, although it was only significant for reproductively active females during the peak breeding season. Diet composition remained consistent regardless of habitat occupied. However, the diet of radio-tracked hares differed significantly from the biomass available in the individual home-ranges; Gramineae were preferentially selected over browse species throughout the year. During winter and in particular during the early breeding season, intermediate feeders, such as mountain hares, ate browse material when the availability of higher quality was restricted. The ability to browse or graze represents a flexible foraging strategy permitting survival and production through periods of changing or unpredictable forage quality and availability.
具有中间觅食策略的食草动物要么在季节性基础上在放牧（大量粗饲料觅食者）或啃食（精饲料选择者）策略之间改变其饮食，要么在任何时候选择混合饮食。确定了一种小型非反刍中间觅食者——山地或北极野兔（Lepus timidus L.）季节性饮食转变的潜在生态原因。对占据苏格兰东北部高地镶嵌景观的41只自由放养的山地野兔（其中18只雌性野兔佩戴了无线电项圈）的饮食组成和相对于可获得性的选择进行了调查。饮食组成通过粪便正构烷烃分析来确定。根据其活动范围中占主导地位的栖息地，佩戴无线电项圈的野兔被指定为牧场、林地或荒原野兔。与先前的研究一致，山地野兔在冬季从以啃食为主的饮食转变为夏季以禾本科为主的饮食，尽管这仅在繁殖高峰期对具有繁殖活性的雌性野兔有显著意义。无论占据何种栖息地，饮食组成都保持一致。然而，无线电追踪野兔的饮食与各个活动范围内可获得的生物量有显著差异；全年都优先选择禾本科而不是啃食物种。在冬季，特别是在繁殖早期，像山地野兔这样的中间觅食者在高质量食物供应受限的时候会啃食植物材料。啃食或放牧的能力代表了一种灵活的觅食策略，使动物能够在饲料质量和可获得性不断变化或不可预测的时期生存并进行繁殖。
