Swallow from Africa in my patch. 1st South America record. Probably NOT!

Un-identified Swallow in Lima. Photo: Fabrice Schmitt.

by Gunnar on March 8, 2011 · 6 comments

in Birding Neotropics

Wishful thinking?

About a month ago, my friend Fabrice Schmitt posted a picture on www.BirdingPeru.com he had taken at Pantanos de Villa, Lima in November last year and sent a message on the BirdingPeru list-server.

He was thinking it maybe was an aberrant Blue-and-White Swallow, or could it simply be the erythrogaster race of  Barn Swallow, although the latter should have a rufous forehead and this bird does not.

Or maybe it was something very rare? Something not South American? Only way to find out was to check the pictures on the internet and in Swallows & Martins: An Identification Guide and Handbook by Turner&Rose (affiliate link).

Swallow in Lima. Fabrice SchmittFinally, checking the pictures one after one, I concluded it was either a Black-and-Rufous Swallow Hirundo nigrorufa from Zambia which does not have a rufous forhead or a Pacific Swallow Hirundo pacifica which just like Barn Swallow has a rufous forheaed with the nearest population around Fiji. There was only one problem. Both species were sedant – non migrating species, although for Black-and-Rufous Swallow the book talked of a particular population breeding in Mwinilunga district that completely disappears post breeding do unknown wintering grounds. Aha, maybe this one is overlooked in Peru :-)

Thus it would be quite far-fetched to think it was a first for South America. Strolling through hundreds of barn swallow pictures on google image search, there are indeed a few pictures of dark chestnut -bellied birds that approaches Fabrice’s bird (although a rufous fore-crown is present). See this – and this.

There is of course very little information we can read from the photo about its flight, tail length or other details to be 100% of its identity – especially if we would like to put a rarity tag on it.

There was a very interesting article on ABA blog a few weeks ago by Ted Floyd applying statistics into Bird-identification – and that is what you have to do, if you don’t have all the facts and the bird flown away long ago..

Check it out: it is long – but it is a good read….So good that I mention it again. Every serious, hot, lister for a regional area should read this, to get him more cool-headed in identification.

http://blog.aba.org/2011/01/indeterminacy.html

In short – account for the probability. Is the probability of a weirdo Barn Swallow – or a weird Blue-and-White Swallow occuring among the millions individuals of both species that regularly occur  in Peru higher or lower than the probability of a first for South America?

So applying Ted’s reasoning on this bird:

I bet that there would be abberrant Barn Swallows or Blue-and-White Swallows that can look like this – even if there is only 1 aberrant like this on every 100000 birds – the odds that one aberrant like this could show up in Peru is still higher than any of those out of place ones.

And that is the best comfort, I can give myself, not being able to tick off a unique out of range possible Black-and-Rufous Swallow over three months ago for my Peru list – in my neighborhood ;-)

What do you think?

Photos: Fabrice Schmitt



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  • http://www.facebook.com/profile.php?id=676543337 Chris West

    Why isn’t it a Black-and-Rufous? That seems plausible. It’s certainly not a regular Barn Swallow. Although, I haven’t the slightest idea what a BAR Swallow looks like (Apparently nobody has ever photographed one and posted the photos anywhere. Not even the IBC has photos.). Given the number of Barn Swallows I’ve seen and the insanely low probability of their being an aberrant one, I’d give probability towards it being a vagrant of some kind. In all probability, this is what you think it is, a Black-and-Rufous Swallow and unfortunately, photos and video weren’t obtained in the required detail to ID it. This is one of those birds that would be simply left unidentified. Not a Barn Swallow, but no certain guess as to its identity. Maybe another will happen by someday.

    • http://www.kolibriexpeditions.com/birdingperu/blog/ Gunnar Engblom

      Chris, the probability of it being an aberrant, although very low, is still immensly higher than a sedant – non migratory black-and-rufous – that noone ever sees or photography should turn up – and get photographed on the wrong continent.
      This is the whole point in Ted Floyd’s argument. Had the same bird been photographed in Zambia….it would naturally have been a 99.999999999% certainty that it was a black-and-rufous swallow

  • Charlie Moores

    Interesting photo. I usually hate to get involved in IDs from a singe photo, but this situation reminds me of pics of an ‘aberrant’ bluish-coloured Cattle Egret that was seen in Lagos that I blogged about – and which totally coincidentally I just moved from an old blog onto Talking Naturally (http://www.talking-naturally.co.uk/unusual-cattle-egret-nigeria/).

    In this case – though it was never proved definitively – it seemed the unusual colour was caused by oil droplet staining, and I’ve often wondered whether staining (from oil, contaminated or iron-rich soil etc) is the answer to problems like these more often than is considered. If you blow up the photo here there is a hint of rufous above the bill (to the left as you look at the image) and surely it’s statistically far more likely that this bird is a stained erythrogaster Barn Swallow than a Zambian vagrant? The colouring on the belly could add to the ‘staining theory’ too.

    Like you say, if you were going on likelihoods alone, this would be a Barn Swallow (it does look like one on shape etc) then this might be an answer – though I’d be the first to admit when hoping to retrospectively identify a country first it’s not a satisfactory one!

    Cheers

    • http://www.kolibriexpeditions.com/birdingperu/blog/ Gunnar Engblom

      There is another mark for Barn Swallow of course…and that is the division of throat and breast. Usually, there is a dark pectoral band here, but as seen on the photos I linked to it can be lacking, and just show a similar division. It could be a molt effect I guess.

  • Birdernaturalist

    Cool photo. We’re lucky to have even that to look at, even if the final ID isn’t likely – so many interesting birds get away. I think the bird is an aberrant Blue-and-white Swallow, simply based on the same size, shape, and behavior as the ones it is with. The whole jizz is Blue-and-white.

    • http://www.kolibriexpeditions.com/birdingperu/blog/ Gunnar Engblom

      Rich, that is what Fabrice also thinks.

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