Wednesday, January 7, 2009

A humbling experience

Readers of this blog will remember my earlier grumblings about the Moxviquil and Huitepec sites, where we barely encountered Golden-cheeked Warblers. I even went so far as to say these sites may have been chosen by Pronatura more because they are Pronatura sites than because they are good Golden-cheeked Warbler sites.

Clearly, I was wrong. I have to take that back.

But first, a little prehistory.

The previous two winters, I worked on this Golden-cheeked Warbler project in Honduras, as part of an effort to describe the wintering ecology of this species, and at the same time monitor the species across the wintering range. That range comprises the mesoamerican pine-oak ecoregion, from the highlands of Chiapas, Mexico all the way down to northwestern Nicaragua. Countries in-between where the species is found in winter are Guatemala, El Salvador and Honduras.

The Honduran results, in particular the distribution of various age/sex classes, were similar to those found in surrounding countries. The results from Chiapas, however, in previous years contrasted markedly with those found in other places. In Chiapas, the percentage of adult males encountered was much larger than that found elsewhere in the ecoregion, a difference which is known from the literature but for which more data is needed.

In order to firmly establish this tendency by minimizing observer bias, the idea came up to switch observer teams between Honduras and Chiapas this year.

That’s the reason why I am in Chiapas now, and why Alberto Martinez did some Honduran sites this season. Incidentally, this is the same Alberto who accompanied me on the trip to Costa Rica late November / early December, to look for Golden-cheeked Warblers there. He’s an excellent observer.

So when he told me a couple of days ago that Moxviquil is in fact the best Golden-cheeked Warbler site in the area, I was just dumbfounded. I know Alberto well enough to tell that he wasn’t bullsh***ing me. But how is it possible then that we found only one goldencheek there, when apparently last year they found 10 individuals here?

So this morning, a Pronatura delegation consisting of Alberto, Efrain, Javier and Jorge joined Hector and myself in the field at Moxviquil, to show us where to find Golden-cheeked Warblers. At times it felt a little as if we were being audited, and to me it seemed there was perhaps some machismo involved as well, although exactly how much of that was real or perceived I couldn’t tell.

And sure enough, within maybe half an hour, Alberto had found two goldencheeks. There I was, having these birds spoonfed to me; a humbling, almost humiliating experience.

I saw both birds well; one was an adult male, the other was an adult female / immature male type, with some white on the throat. This last bird I got a crappy picture of (above).

These birds were in a flock close to the field station, presumably the same flock we did on one of our first days here, when I was still sick and went right back to bed afterwards. I do remember thinking it was a rather minimal effort that day. Birds moved fast up the steep slope and I was barely able to follow then, constantly panting, coughing and spitting, and with a pounding headache.

An hour and a half later Alberto found a third bird. This bird he lost almost immediately after he found it, and for a while nobody else saw it, until about 20 minutes later Javier called it out. Yup, it was a goldencheek alright. This bird also had white fringes on the central throat feathers, but a black chin, and dark olive upperparts. It was called an immature male but I think it may just as well have been an adult female.

This bird was found exactly 200 m on each side away from other flocks we had described a couple of weeks ago! We saw a Crescent-chested Warbler and a Wilson’s Warbler nearby, and we heard a Greater Pewee in that area, but otherwise this hardly appeared to be a flock.

So clearly these birds are here. Why then did we see only one, during 5 mornings of field work here?

I think there may be a couple of explanations. First, Alberto and the others know these sites much better than we do. Instead of walking around looking for warblers, they went right to the spots where in previous years they had found goldencheeks. Second, this was a very strong team. For some reason, my teams have always been ‘weak’ teams, with only one skilled observer who doubles observing and note-taking duties, while also teaching the other observer how to identify birds in these mixed species flocks. And even today’s strong team failed to find goldencheeks in some flocks at spots where in previous years they were found.

The flock with the two goldencheeks we will do again, when we return next week.

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