The use of spatial memory by grazing animals to locate food patches in spatially heterogeneous environments: An example with sheep
The use of spatial memory by grazing animals to locate food patches in spatially heterogeneous environments: An example with sheep
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DOI：
10.1016/0168-1591(96)01077-5
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发表时间：
1996-11-01
影响因子：
2.3
通讯作者：
Krebs, JR
中科院分区：
文献类型：
--
作者：
Edwards, GR;Newman, JA;Krebs, JR
通过两个实验考察了绵羊记忆食物斑块的空间位置的能力。在第一个实验中，将斑块(塑料碗)放置在草地上，并随机分配一些斑块来容纳食物(绵羊丸)，将单只绵羊放入田野多次，每次访问的斑块数量都被记录下来，直到所有包含食物的斑块都被定位为止，绵羊被测试了三个复杂程度：水平排列的8个总斑块中的一个食物斑块；8×2网格中16个总斑块中的2个食物斑块；8×4网格中32个总斑块中的4个食物斑块。所有的补丁都相隔5米。20只绵羊在8个水平中被测试，10只绵羊在两个更复杂的水平中被测试，在所有复杂性水平下，绵羊在第一次暴露后12h回到含有食物的斑块，水平好于它们随机搜索的水平，在暴露于斑块分布的6次之后，绵羊几乎每隔12h访问食物斑块。在第二个实验中，每只羊在草地上水平排列的8块斑块中寻找一块含有食物的斑块，10只动物被测试位于食物块后面的一根线索(白三叶草皮)，另10只动物没有。在球杆顶部放置了一个铁丝网笼子，这样它就可以被看到和闻到，但不能被吃掉。绵羊在有线索和没有线索的情况下学习食物块的位置，但当线索存在时学习速度更快，当线索和食物块的位置在试验之间随机切换时，绵羊首先使用空间记忆并转到之前食物块所在的位置，但在发现没有食物使用的关联时，线索和食物块之间的关联将EO到新的食物块位置。利用空间记忆以及线索和奖励之间的联系的能力将有助于绵羊提高它们遇到首选食物块的速度，并更好地利用食物资源中的空间异质性。
The ability of sheep to remember the spatial location of food patches was examined in two experiments. In the first experiment, patches (plastic bowls) were laid out on a grass field and some of the patches were randomly assigned to contain food (sheep pellets), Individual sheep were released into the field on a number of occasions and on each occasion the number of patches visited until all the patches that contained food had been located was recorded, Sheep were tested at three levels of complexity: one food patch among eight total patches laid out in a horizontal array; two food patches among 16 total patches laid out in a 8 x 2 grid; four food patches among 32 total patches laid out in a 8 x 4 grid. All patches were 5 m apart. Twenty sheep were tested in the one in eight level and ten sheep in the two more complex levels, At all levels of complexity, sheep returned to the patches that contained food, 12 h after first exposure, at a level better than that expected if they had searched at random, After six exposures to the distribution of patches, at 12 h intervals, sheep visited the food patches almost exclusively. The performance of the sheep did not decline when the time between successive visits was increased to 72 h.In the second experiment, individual sheep searched for one patch that contained food among eight total patches laid in a horizontal array on a grass field, Ten animals were tested with a cue (turf of white clover) located behind the food patch, and ten animals without. A wire mesh cage was placed over the top of the cue so that it could be seen and smelled, but not eaten. Sheep learned the location of the food patch with and without cues, but learned faster when a cue was present, When the location of the cue and food patch was switched randomly between trials, the sheep used spatial memory first and went to where the food patch had previously been located, but on finding no food used associations between the cue and food patch to eo to the new food patch location. The ability to use spatial memory and associations between cues and rewards would help sheep to increase the rate at which they encounter preferred food patches, and to exploit spatial heterogeneity in the food resource better.