Aberrant swift or something rarer? (1 Viewer)

[Evan Atkinson]

Hey all, photographed this swift from my garden 20 minutes ago, in Chislehurst, Kent, UK and it’s throwing me off because of the long tail, which is very thinly forked and a white patch on the back of the bird. I know back of the camera pictures are difficult to ID, I will get some uploaded in an hour or so. Is this just an aberrant swift or something rarer?
Many thanks,
Ev

 

[Butty]

I don't think the tail is particularly long or particularly forked. We're looking at the underside here, so we can't see the 'back': the pale area on the rear flank/vent is just caused by the light - see similar paleness on side of head in pic 1. (Normal) common swift.

 

[Evan Atkinson]

I might have some pictures of it on the back so I will check now.

 

[Evan Atkinson]

Found some other pictures and it's just a common swift, no white on the back at all.

 

[Bismarck Honeyeater]

Well spotted. It is an aberrantly plumaged Common Swift. It has pale markings in the wing too.

 

[Evan Atkinson]

Well I'm glad I didn't put it out as a pacific lol, as I was certain it was one but wanted to check. Good thing I did lol.

 

[KenM]

Keep up the good work Ev.👍

 

[Butty]

Could you upload the originals of these photos, and the other ones that you have?

 

[Farnboro John]

Well spotted. It is an aberrantly plumaged Common Swift. It has pale markings in the wing too.

If you compare the two photos the darker areas move, its just how the undersides of the individual feathers are presented to the light in each case.

John

 

[Butty]

When you post the photos, could you confirm which of them you know to represent the same bird(s)? This will be important in deciding on possibilities such as Farnboro describes above. As I indicated, effects of light are the first thing to eliminate.

 

[01101001]

I don't know, but, very incidentally, I read this article yesterday, and numerous features from the part where the guide deals with spring/summer pallid swift identification seem to vaguely match features seen in the photos. I guess it involves much wishful thinking, though.

 

[Evan Atkinson]

As asked, here are the original files of the aberrant swift I found. My first impressions were pacific or white-rumped at the time, but as I took more photos, it is clear that there is no white on the rump at all, and that it was either the light or an aberrant individual. I've labelled them so that you can see where I was thinking it was a mega to the actual impression of an atypical common swift.

 

[Farnboro John]

All of the white-rumped swifts have exactly that: highly contrasting bright white rumps (in any light). Yours doesn't.

That immediately reduces the choice to Common vs Pallid and there isn't anything indicative of Pallid showing on the bird, just a spot or two of directional sunlight.

For small distant images of fast moving birds high in the sky they are not bad (this doesn't mean they are good, just that in the circumstances its hard to get anything at all) and they help the identification process. I think though that you need to recognise now that "rare" means just that: maybe one rare swift in the whole of Britain at a time (or less) and you need to default to common species unless you have an obvious rarity bang to rights. You might look at the twitter images of the Sumburgh Head Pacific Swift with that in mind.

Aberrants are not all that frequent either!

Cheers

John

 

[Butty]

It is an aberrantly plumaged Common Swift. It has pale markings in the wing too.

No indication of anything but effects of light.

 

[Jeff Woad]

All part of the learning experience Ev4, well done for asking.

Always take a holistic view of ID and don't focus too much on just one feature- there are some ridiculous threads on here depicting poor images of birds in unusual lighting where one lone barely discernable feature is being used to suggest an ID- don't fall into that trap!

JW

 

[Essex Tern]

…..and you need to default to common species unless you have an obvious rarity bang to rights.

Fantastic piece of advice.