Chiang Ming-liang of the Wild Bird Society of the ROC explains that, living as they do high in the air, where there are no materials for nests, the swiftlets must build their nests on cliffsides, and thus use their own sticky saliva to bind together plant matter that has been blown up into the air by the wind, or some of their own feathers, to make a nest.
中華民國野鳥學會江明亮解釋，在資源不如陸地的天空，雨燕欲將巢黏附於絕壁高處，就以本身含有膠質的唾液，混合地面吹至空中的植物，或自身的羽毛黏結成巢。