Be wary with woodcreepers

The only woodcreeper that comes to my San Antonio garden is the Streak-headed woodcreeper (Lepidocolaptes souleyetii), or is it?  Are they called Streak-headed or Streak-headed?  Anyway, it’s a medium-sized woodcreeper that, when seen in good light, can be fairly safely distinguished from all others, with the exception of the Spot-crowned woodcreeper (Lepidocolaptes affinis), or is it Spotted-crowned? Are those streaks or spots on its head? you ask yourself as you carefully peer.   The bird nips around the other side of the tree trunk, clambers jerkily upwards each time you settle the binoculars on it, and otherwise makes identification as difficult as possible.  Here are the two culprits:

The bird guides (Garrigues & Dean, Stiles & Skutch) seem quite helpful because, although they differ in the spelling of the names and also in estimating the size of the two species, they agree on the fact that the Spot-crowned is the only one likely to be found above 1500 m.  Stiles & Skutch concede that it wanders down-slope to 750 m on rare occasion, while Garrigues & Dean (with more up-to-date information) confine it to 1000 m, and then only rarely.

My location in San Antonio is problematic because, at 1200 m, both species would seem to be possible, though the Streak-headed should be much the more likely.  On the basis of this information, as well as the call-note that I occasionally heard (always the long descending trill), I have confidently marked my woodcreepers for almost two full years as souleyetii. (Note how I’m having a go at the Latin names now that I’m getting help from real ornithologists down at CATIE).

What a shock then, in my first week of bird-banding at CATIE, to have both species right in front of my nose within an hour of each other.  At the same time, however, what a fantastic opportunity to make a direct comparison, and I was even able to take photos for posterity (my grandchildren).  The Spot-crowned was the first to blunder into the net, and of course I immediately pronounced it a Streak-headed woodcreeper.  After all, the CATIE grounds are located at about 650 m, below even the wildest estimates of the bird guides for the range of the Spot-crowned.  I was wrong of course, but the appearance of the Spot-crowned was no surprise to Alejandra, who is in charge of the CATIE monitoring programme.  Careful observation and measurement of the bird in hand confirmed it as the Spot-crowned, and I’m happy to report that, even though it has streaks all over the place, the marks on the head really are spots and not streaks.

It seemed only minutes later that we had another woodcreeper in the nets, but this time, lo and behold, the Streak-headed variety.  With the bird in the hand, the size difference is quite clear, and, when we put him on the scales, this bird weighed considerably less than the first.  Not only that, but the engravings on the head are clearly streaks when you can see them closely.  I invite you to inspect the photos, which are not particularly wonderful but do show the differences.  In addition, the Streak-headed gave us a nice little trill goodbye when he finally flew off.

So now I know, firstly, that it will be difficult to be sure which species I’m looking at in the field if the bird remains mute, and, secondly, that it’s very difficult to log all information about birds, even in field guides as well researched as those mentioned above.

I’m assuming, of course, that these last two photos match the bird I see at home in San Antonio.  No matter what, all this made for another really great day in my first week of bird-banding.  We were joined for this day by Fabrice’s family and by 15-year-old nature enthusiast Delicia Ríos from Peru.  Great companionship in a marvelous environment.

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