ML647175505

观察细节

Cautiously assigned to Bank Swallow initially but call was drier, more trilling and maybe higher pitched and they were generally greyer than that species, which I have subsequently looked at closely here in HK - certain structural/jizz differences seem to be present too. A lot of these birds were rather 'bat-like' in jizz, whereas Bank (being longer winged, presumably, and slightly longer tailed) is somewhat more Barn Swallow like, I have noticed, in a similar way to Asian vs Siberian House Martin. This was a large flock and Bank Swallows and Asian House Martins may both have also been present in it, but the vast majority were this species.