neotropical Swift ID (1 Viewer)

I've been seeing a small group of swifts flying around my house but I am having trouble identifying them. I am thinking that they might be Short-tailed Swifts (Chaetura brachyura).

I have only managed to note a few features as they zip around in the sky above my house.
(1) It is a Chaetura sp. (I've ruled out the larger swifts becuase of their size and a few others because of obvious differences). (2) It has grey on its rump which appears to extend onto its tail as well. (3) It has no striking white areas on its body. As far as I can tell, it is all black with a grey rump and tail. (4)Its tail is about equal in length to its head.

With the combination of these few features and the habitat (a village mostly surrounded by sugar cane fields and bushy areas, situated next to the river), is it possible to ID it?
Thanks.

Note: There are 4 possible Chaetura species in Guyana.

Chapman's Swift (C. chapmani)
Short-tailed Swift (C. brachyura)
Band-rumped Swift (C. spinicauda)
Grey-rumped Swift (C. cinereiventris)

Taken from Braun, M. J., D. W. Finch, M. B. Robbins, and B. K. Schmidt. 2000. A field checklist of the birds of Guyana.

Neotropical swifts can be very difficult and some species probably can't be ID'ed for certain in the field. A few hints on Chaetura Swifts in Guyana:

Grey-rumped: Grey (not white or brownish) patch on rump extents onto tail. Shift from black back to grey rump is clean-cut and the contrats is obvious. Underparts usually dark greyish, slightly paler on throat.

Band-rumped: In Guyana the whitish patch on the rump is quite narrow and it certainly doesn't extent onto the tail. It contrasts strongly with the rest of the dark upperparts. Underparts dark grey and throat usually appear whitish.

Short-tailed: Has a very short tail and the pale patch on the rump extents onto the tail - only the very tip is dark (usually, the complete upperside of the tail appear pale in the field). Appear broader-winged than the previous two species. Appear all dark below. The wing-beats of this species are noticably slower than the wing-beats of the other members of this genus.

Chapman's Swift: Rump brownish-grey (incl. most of the tail), but contrast with black back relatively small (the change from the greyish-brown rump to the black back isn't as clean-cut as in the previous species). Underparts appear dark brownish-grey, the throat often being marginally paler. Larger than the three species mentioned previously. Only recorded infrequently.

Ashy-tailed: Not mentioned by you, but probably occur in Guyana even if it hasn't been recorded there yet. Very similar to Chapman's (incl. size) and it is doubtful the two can be separated for certain in the field. Ashy-tailed is marginally browner above (the back of Chapman's is a bit blacker). Furthermore, the undertail coverts are marginally paler than the rest of the dark brownish-grey underparts (undertail coverts concolour with the rest of the underparts in Chapman's). Would be an austral migrant in Guyana and can be expected in the South Hemisphere winter.

Regularly, several species can be seen in a single flock, so look out for "strange individuals" that appear different in size or shape compared to the remaining individuals in the flock.

Thanks for the info, Rasmus. One problem for me is that I have never seen any other swifts than these, so I can't tell if it is "bigger than Short-tailed" or "broader-winged than Grey-rumped", although I am sure these hints will be helpful. I do not see these birds often, and, as you know, it's not easy to keep your bins on them.

BTW, do you think I could eliminate any of these species by habitat?
Thanks

Jacamar said:

BTW, do you think I could eliminate any of these species by habitat?

Click to expand...

Not for certain. The commonest species in Guyana is likely to be the Band-rumped.