Watching the ecology of genus Apus is not easy. However, if you study the ecology of swift, maybe you can enjoy watching. Today's theme is Pacific swift. In Japan, Pacific swift and House swift in genus apus and White-throated needletail in genusHirundapus are the breeding birds. And few record of Common swift, White-rumped swift and Silver-backed Needletail are existed. But I don't know how to distinguish Common shift with Pacific swift. In the morning, swifts made a flock. They called "li-li-li-" each other. This flock was named "Screaming Party" by David Lack. He reported that screaming parties are seen in all season, however the most considerable in migtrate season. however interestingly, this behavior is not related to mate choice. I couldn't find any report of this behavior, but I believe that this behavior contributes to the peace of the breeding population.
ヒメアマツバメ (Apus. nipalensis) House Swift 160303 C Taiwan
This photos are House swifts I took at Taiwan. Recently the number of the breeding House swifts in Japan increases but about 20 years ago this birds was rare in Japan. In Taiwan, this species is common breeding species. Moreover, recently some wintering population of House swifts are seen in Japan. Many birder know that if they fly near us, the sound of wings is expressed like "bum" or "whiz". But the sounds many people listened were made by swift that during foraging near ground. Then, what sounds they make when they fly at high sky? The only way to hear the sounds is to go to the high mountain. I listened the sounds many time on the high mountain when they fly around 3500m. The sounds are like "crunch sounds". It is so amazing. Recently reports indicated how they deal with heat problems, it also interesting. I think it is good way to enjoy watching swifts is studying their ecology. Anyway two days ago I finished the admission exam of master course. I hope I could pass it.