Edible-nest Swiftlet

Swiftlets are all so similar with overlapping plumage variations and mixed flocks that most can only be reliably separated at the nests which are very different for each species. Dull grey/brown belly indicates either Edible nest (C. fuciphaga) with a white nest or Black-nest (C. maxima) with a dark grey nest for these birds. The latter normally has a much paler throat when compared to the belly.