Wich S A, Fredriksson G, Sterck E H M
Utrecht University Social Ethology Group, P. O. Box 80086, 3508 TB, The Netherlands.
Primates. 2002 Jan;43(1):19-27. doi: 10.1007/BF02629573.
Food availability is one of the basic factors affecting primate density and socioecology, but food availability is difficult to assess. Two different ways to obtain accurate estimates of food availability have been proposed: using phenology data or using the behaviour of animals. Phenology data can be refined by only including trees that are large enough to be used; including (potential) tree species in which by the concerned primate species forage; or including (fruiting) trees of these species that actually produce fruit. Alternatively, the sizes of the actually visited trees (foraging trees) give an estimate of fruit availability. These measures are compared for three sympatric primate species at the Ketambe Research Station, Sumatra, Indonesia: the Thomas langur, the long-tailed macaque and the orangutan. The sizes of fruiting trees and the foraging trees are larger than the potential trees. The sizes of the potential trees and of the fruiting trees are similar for the three primate species. This, however, is not reflected in the use of trees: the langurs forage on average in trees of similar size to those producing fruit, whereas the macaques and orangutans forage in trees larger than those producing fruit. The use of trees does not necessitate a different cut off point of included dbhs for the three compared primate species. The use of trees of different sizes, however, may be regulated by food competition. This indicates that sympatric primates make different foraging decisions and that behavioural measures of food availability will be less reliable.
食物可利用性是影响灵长类动物密度和社会生态学的基本因素之一，但食物可利用性难以评估。已提出两种获取食物可利用性准确估计值的不同方法：使用物候数据或使用动物行为。物候数据可以通过仅纳入足够大以供利用的树木来细化；纳入相关灵长类物种觅食的（潜在）树种；或纳入这些物种中实际结果的（结果）树木。或者，实际被访问树木（觅食树）的大小可给出果实可利用性的估计值。对印度尼西亚苏门答腊岛凯坦贝研究站的三种同域灵长类物种进行了这些测量的比较：托马斯叶猴、长尾猕猴和猩猩。结果树和觅食树的大小大于潜在树。三种灵长类物种的潜在树和结果树的大小相似。然而，这并未反映在树木的利用上：叶猴平均在与结果树大小相似的树上觅食，而猕猴和猩猩在比结果树更大的树上觅食。对于所比较的三种灵长类物种，树木的利用并不需要不同的纳入胸径截断点。然而，不同大小树木的利用可能受食物竞争调节。这表明同域灵长类动物做出不同的觅食决策，并且食物可利用性的行为测量将不太可靠。
