Numerous criteria morphological allowing discrimination between two species were deferred ('Y' alar, ratio of phalanges, hump between the nostrils, etc.) but it seems that none of them does either reliable to 100% in the whole of the range of both species (obs. pers.).
Wengi vigezo kubadilika kwa maumbile kwa ajili ya kubagua aina mbili na kuripotiwa ('Y' alaire, uwiano de phalanges, hump kati ya puani, nk) lakini inaonekana hakuna hata mmoja wao ni wa kuaminika 100% katika aina mbalimbali mbili (obs. Pers.).