Subspecies: mexicana
Adults. It can be difficult to see the complete white collared under some circumstances, picture 2 (picture 3 same but lightened), why it is necessary to notice other field marks as well. In this case, the deeply forked tail is a good clue to separate the species from the otherwise very similar White-naped Swift. However, as seen in picture 4 even this can cheat if the tail is completely spread out... A good flock of 100 present this day.
Subspecies: mexicana
Adults. Probably very regular up at the Yelapa High Point (Yelapa Tapa) during their daily foraging raids. Here typical profile and plumage, with the narrow arm, forked tail and white collar.