This Chaetura swift was drinking
from the spring pool at Fort Clark Springs, Brackettville, Kinney
County, Texas on May 19, 2005: Note that the day was overcast,
producing an even but brightish light (this was at c. 3pm in the
afternoon) - thus there is little strong light to cause misleading
contrasts, and the pics below are a fairly accurate representation
of the bird in life:-
The most striking feature was the pale uppertail coverts,
rump and lower back: note that this profile shot - taken
in a duller moment - is probably less prone to reflective distortion
than the pics further down that show the bird going away from
the lens - in real life the bird looked like this image - i,e,
with a clear contrast between the rear and front halves of the
body.
Also note the short tail compared to the wings:
The forehead seems to be a bit paler, the pale gray of
the cheeks comes up behind the eye, the very pale throat appears to abruptly change to a dark tone on the upper chest, and the dark lores appear to be pinched a bit ahead of the eye:
In this profile shot note the pale crescent ahead of the eye, breaking the dark lores (A); the fairly clean transition to slightly - but obviously - paler undertail coverts (B); the underparts changing from whitish on the chin/upper throat to very dark on the chest in a narrow area of the lower throat (C1 - C2):
note this the pic below that with the bird a bit higher from the
water, the reflection shows distinctly paler undertail coverts
- this can also be seen slightly on the side of the actual bird:
in enlargement below, note the indicated pale area on the lateral undertail coverts - this aligns with the pale boundary in the image above this one:
Note in the four images below how the contrastingly pale rump and uppertail coverts extend virtually to the tip of the tail:
In the two images below the tail is spread, showing the upper side of the actual tail feathers - these are grayish, not dark, yet still darker than the contrastingly paler uppertail coverts:
There is no indication of spines at the tail-tip; these images may not be detailed enough to show such a feature, but it is interesting to note that Chaetura (andrei) meridionalis (see below) has extremely short spines - the longest barely more than 2mm, compared with the 7.5mm of Chimney Swift C. pelagicus.
The combination of short tail, extensive pale rear-end (reaching the tail-tip), less-dark tail feathers, dark underparts with short contrasting whitish throat plus slightly paler undertail coverts, and small pale crescent ahead of the eye seem to match Chaetura (andrei) meridionalis - also known as Sick's Swift. The "Swifts" monograph (Chantler and Driessens 1995) states that paler undertail coverts are diagnostic of this species (including form andrei) and Short-tailed Swift C. brachyura. The form C. (a.) meridionalis is an Austral migrant, breeding in southern Brazil and northern Paraguay and Argentina from August - January (Oct - Nov in Matto Grosso, Brazil), and known from a small number of specimens and a few sightings from Venezuela, Colombia, and central Panama (once) from August and September, with one record from the Falkland Islands/islas Malvinas in March. Migrants are known to be moving into the pan-Tepui region in May (per Sick 1993).