Chapman's swift, Trinidad? (1 Viewer)

[bugmat]

Hi All

I'm thinking this just might be a chapman's swift. This species is rare but is known to be resident in the area I saw this bird (central mountain range of Trinidad).

This swift was significantly larger than the approximately 12-15 short-tailed swifts that were also in the air.

By elimination it's not a Short-tailed swift (which is black, bar the white undertail coverts though similar shape, just larger), fork-tailed palm swift (tail isn't long & forked, swift too stocky) and was imo too large to be band-rumped or grayrumped swifts either (which are swifts with very belly to dark undertail covert/vent areas).

It's too brown/grey to be a white-collared swift (no white colalr against black) and also too light to be a juvenile chestnut-collared swift (or adult of course w/o the chestnut collar) but it was of a similar size.

Reading this article here: http://www.planetofbirds.com/chapmans-swift-article-1, It says

It is dark blackish brown on the wings, back, nape, and crown, whereas the rump and upper tail coverts are lighter brown or grayish brown. The under parts are also brown to grayish brown, although somewhat lighter on the throat. Specimens of birds in fresh plumage exhibit a distinct greenish iridescence to the feathers of the darker areas. This is purely a structural gloss. With the natural wear of the feathers, it changes from the greenish to a bluish purple gloss and eventually to a dull, completely lusterless black-brown shortly before the annual molt.
In the field, C. chapmani appears to be a dark bird, although noticeably browner on the rump and under parts and larger than its Trinidadian congeners. In other parts of its range it would appear very similar to C. pelagica and in color, but not in size, to some races of C.vauxi.
The superficial resemblance of the three closely related and largely allopatric species, C. chapmani C. vauxi (including C. richmondi), and C. pelagica, has led to the suggestion that they be considered races of a single species (Lack, 1956). I think that there are sufficient morpho- logical differences, however, as pointed out by Wetmore (1957), for maintaining both C. chapmani and C. vauxi as distinct species.

Having read that I looked at images of C. pelagica (chimney swift) & C. vauxi (Vaux's swift) and I also think those birds are similar to this specimen, no?

C. pelagica: https://www.google.com/search?q=chaetura+pelagica&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjjlpe3sLrYAhXsSd8KHbu7CHMQ_AUICigB&biw=1408&bih=779

C. vauxi: https://www.google.com/search?biw=1408&bih=779&tbm=isch&sa=1&ei=bw5MWvbTGIWe_QbI7LR4&q=chaetura+vauxi&oq=chaetura+vauxi&gs_l=psy-ab.3...32264.33010.0.33248.5.5.0.0.0.0.0.0..0.0....0...1c.1.64.psy-ab..5.0.0....0.uFcxgcEP4y0

I tried to compare it to chapman's swift pics online, but there are only a handful which are clear shots, mostly from here:

https://www.hbw.com/ibc/species/chapmans-swift-chaetura-chapmani


Any comments/shooting down of my logic?

 

[Andy Adcock]

The contrasting, pale throat suggests Band-rumped which would be far more likely.

I honestly think that without a pic of the back and rump, you'll struggle to get this accepted as Chapman's?


A

 

[bugmat]

Edit to clarify sadly I was only able to get dorsal views, which is why I need ID help. I know theoretically it could be Vaux's swift (seen in Venezuela/ northern S. America) or a Chimney swift (eastern north America but which are strongly migratory) but neither of these have ever been confirmed or reported here.

 

[bugmat]

The contrasting, pale throat suggests Band-rumped which would be far more likely.

I honestly think that without a pic of the back and rump, you'll struggle to get this accepted as Chapman's?


A

Hi Andy thanks for commenting. It's not band-rumped - I've seen those several times as they are very common here in certain areas (locally common) excluding the area this bird was seen (BRS have never been reported there).

BRS are also not as large as this was and are the size of short-tail swifts. The colour dorsally is not that of a BRS which is very dark, almost black from throat downwards, bar the rump which is white (see attached photos of BRS here - sort of the opposite to short-tail swifts).

For the same reason it isn't grey-rumped - the colour dorsally is too light and it is significantly larger.

As I said before I saw your post (my page didnt refresh sorry) it could conceivably be C. vauxi or C.pelagrica also, but I went with C. chapmani as a start because it had been reported in that general location before (though decades ago) and a similar behaviour (single bird associating with STS) has also been documented.

Both BRS & GRS are usually in flocks and not seen singly (here at least).

 

[njlarsen]

Two comments:
Dorsal really is the upperside, you mean ventral.

Humans are generally really poor at judging distance and therefore also at judging size. Did you have another bird at the same distance that allowed direct comparison for you to say this is a larger species?

Niels

 

[Andy Adcock]

With this tail, there are only a few things it could be, I don't think it's uniformly dark enough underneath for Chapman's? For me, there is an obvious contrast between throat and underparts.


A

 

[bugmat]

Two comments:
Dorsal really is the upperside, you mean ventral.

Humans are generally really poor at judging distance and therefore also at judging size. Did you have another bird at the same distance that allowed direct comparison for you to say this is a larger species?

Niels

SMH Not sure why i keep saying dorsal - correct. I think it's because I'm so upset at not getting a dorsal view, thanks.

As to the size, yes - several of the dozen or so short-tail swifts (which were the other species present) and this bird were flying directly overhead (partly why i couldn't get dorsal views). It was the 2nd or 3rd pass when I realised this bird was not one of the STS. Other observers were there who also noticed the size difference.

Humans are far from perfect, but also pretty good at judging when they see something unusual or different from what they are accustomed to seeing on a regular basis (which is how I'd classify the smaller swifts seen here)

 

[bugmat]

With this tail, there are only a few things it could be, I don't think it's uniformly dark enough underneath for Chapman's? For me, there is an obvious contrast between throat and underparts.


A

The chapman's swift is the most uniform and lightest (relatively) underneath of the Trinidad swifts being grey-brown.

Now as I said it could easily be Chimney or Vaux's swift also - these 3 are noted for being hard to differentiate w/o seeing the top of them. This excerpt is from wikipedia on C. pelagica (referenced rom various S. American bird field guides)

The chimney swift looks very much like the closely related Vaux's swift, but is slightly larger, with relatively longer wings and tail, slower wingbeats and a greater tendency to soar. It tends to be darker on the breast and rump than the Vaux's swift, though there is some overlap in plumage coloring. It can be as much as 30 percent heavier than the Vaux's swift, and its wings, which are proportionately narrower, show a pronounced bulge in the inner secondaries.The chimney swift is smaller, paler and shorter tailed than the black swift. In Central America, it is most similar to the Chapman's swift, but it is paler (matte olive rather than glossy black) and has a stronger contrast between its pale throat and the rest of its underparts than does the more uniformly colored Chapman's swift.

THis swift seems to have that contrast between pale throat and rest of its underparts, and as I said before it looks equally like those 2 species. I started with Chapman as neither Chimney or Vaux have been reported here...

but having spoken to a local expert he says because of the migratory tendency of Chimneys (migrating from eastern N. America to S. America around this time) it could be this, and...

Likewise Vaux's swift is found in souther N. America, C. America and northern S. America (including Venezuela) but has never been recorded here either.

Kaufman's FG of birds of NA says the vau is slightly smaller and paler on the throat and rump vs the rest of its underparts compared to the chimney swift which it says is just grey overall.

So it could be any of the three. :-C

edit: attached a shot from my field guide (if that isn't allowed I'll delete it) of the page with Chapman's swift showing how light anduniform it is underneath vs other swifts.

Also I noted tail length is a field demarcation in several guides between Chapman's (relatively short) and Grey-rumped/Band-rumped (relatively long)

 

[njlarsen]

I have never seen Chapman. I think the images are compatible with Chimney, but possibly also with other possibilities. I have seen Chimney in the US and have a 95% sure observation from Dominica.

Niels

 

[bugmat]

I have never seen Chapman. I think the images are compatible with Chimney, but possibly also with other possibilities. I have seen Chimney in the US and have a 95% sure observation from Dominica.

Niels

I am hoping the local expert I spoke to can get something definitive from the ventral view when they consult several S. American experts. Thanks for the comments.