蓝喉蜂虎的捕食行为与食性

Diets and Predatory Behavior of Blue-throated Bee-eater Merops viridis

在我国有分布的7种蜂虎科鸟类中,蓝喉蜂虎(Merops viridis)分布范围最广,但相关野外研究还比较少。2011~2016年,我们以江西省吉安市郊区的一个蓝喉蜂虎种群为研究对象,在观察野外捕食行为的基础上,记录了其食物种类,研究了该鸟的食性。蓝喉蜂虎的食物主要是蜂类、蝶类和蜻蜓类昆虫,其被捕食频次的百分比分别为26.0%、26.3%和38.3%。其中,繁殖前期以蜂类居多,繁殖后期以蜻蜓类居多,数量比例存在显著的季节性差异。这种差异可能是昆虫生活史差异造成的。网络图片资料佐证了其食物种类主要为以上3类昆虫。在吞食食物前,蓝喉蜂虎会对不同类群的昆虫进行不同时长和不同方式的处理。此外,野外研究发现,产卵期蓝喉蜂虎巢室中散布着可能被吞食过带有食物残渣的小型贝类碎片。通过实验筛选营巢河滩地的沙土,发现这些贝壳碎片是外来。这表明,蓝喉蜂虎可能通过取食小型贝类贝壳,在产卵期获取短期额外的钙质补偿。蓝喉蜂虎在其分布区内属不常见鸟类,但其捕食的主要昆虫类群在我国南方比较常见,这说明食物不是限制该鸟分布的原因。蓝喉蜂虎是一个极具观赏价值的美丽小鸟,当前亟需深入研究,为该鸟的保护提供决策依据。

The Blue-throated Bee-eaters （Merops viridis） is widely distributed in south China, however, received little concern for basic biological studies. During 2011﹣2016, we observed the predatory behaviour and recorded the prey items of Blue-throated Bee-eaters in the suburb of Ji′An, Jiangxi Province. Our results showed that 90.6% of prey items were insects from taxa of Hymenoptera （26.0%）, Lepidoptera （26.3%） and Odonata （38.3%）. The percentages of different insect types varied significantly between early- and late-breeding seasons, possibly caused by the differences in life history of different insect taxa. The birds dealt with different kinds of insects with different ways before swallowing those foods. In addition, we also found there were mussel shells scattered in the bottom of the nest chambers of the Bee-eaters （Fig. 1）. The birds may forage on small mussel shells to meet the additional calcium needs during egg-laying stage, because the mussel shells were stained with debris of insect corpses, as the marks of being swallowed and digested. Although the insect preys were relatively abundant in south China, Blue-throated Bee-eater is not common in its distribution range, suggesting that food supply might not the limiting factor. Limited distribution and habitat loses are threatening the survival of the Blue-throated Bee-eater, more studies are needed in the future to provide suggestions and measures for its conservation.