云南紫溪山巨春季觅食树种选择

2010年3～5月在云南省楚雄市紫溪山省级自然保护区采用所有事件取样法(all-occurrencerecording),对巨(Sitta magna)觅食树种、觅食树干大小和觅食部位选择进行了观察。采用中心象限法(point-quarter technique)对研究区域的植物重要值进行了测定,用以计算觅食树种的选择系数。结果表明:巨对觅食树种具有明显的选择性,主要选择在云南松(Pinus yunnanensis)觅食,觅食时间占97.46%,觅食次数占96.54%,两者均极显著多于其他树种(P0.01),选择系数为43.89;巨对云南松的树干大小也有选择性,主要在胸径大于15 cm的大树(云南松中、成林)觅食,觅食次数占95.60%;在云南松的树干、枯树枝、活树枝和针叶丛4个部位中,巨偏爱在树干觅食,觅食时间占61.32%,觅食次数占57.02%,两者同样极显著多于其他部位(P0.01)。食物种类及丰富度、种间竞争和巨自身的形态特征等可能是影响巨对觅食树种、觅食树干大小和觅食部位选择的原因。

Tree Species Preferences of Giant Nuthatch during Spring in Zixi Mountain, Yunnan Province

Tree-species preferences of Giant Nuthatch during Spring were examined by observing foraging behavior of Giant Nuthatch (Sitta magna) in Zixi Mountain nature reserve, Chuxiong, Yunnan Province from March to May, 2010. Foraging tree-species, foraging tree trunk size and foraging positions were studied by all-occurrence recording. The results showed that Giant Nuthatch mainly foraged on Yunnan Pine (Pinus yunnanensis), the preference index is 43.89 which was much higher than other species' preference index. 97.46% of foraging time and 96.54% of feeding times were recorded on Yunnan Pine. Both of foraging time and feeding times were significantly different between Yunnan Pine and other species (P<0.01). Bigger Yunnan Pine were preferred, 95.60% of feeding times occurred on trunks that bigger than 15 cm in diameter. Among Yunnan Pines' main trunks, branches, sticks and needle-leaves, 61.32% of foraging time and 57.02% of feeding times were recorded on trunks. There was an extremely significant difference between trunk and the other 3 parts (P<0.01). Interspecific competition, insect species and abundance and morphological characteristics may be the reason of those selections for Giant Nuthatch.