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The Peregrine Fund Notes From The Field
Aplomado Falcon Updates - March 2010
Brian Mutch — in Aplomado Falcon Restoration    Share

During the second week of March, Angel Montoya, Paul Juergens and I once again completed our annual survey in the Chihuahuan Desert of West Texas, looking for nesting Aplomado Falcons. Unfortunately by the end of the second day, and having collectively driven more than 1,200 miles in much of the best habitat we could look at, only one adult pair was located. This pair was observed at a yucca on the Baeza Ranch complete with a very nice Chihuahuan Raven nest.

Day after day, the same scenario played out: the three of us would leave our field house in the early morning hours and spend very long days looking for something which for some reason had seemed to vanish from this country, “our falcons.” Each evening, we would get together over dinner and speculate as to what possibly could have happened to nine pairs of breeding-age Aplomados over the course of one fall and winter? The passing days continued to reveal nothing but a discouraging lack of falcons and by the end of the survey week, our humor and spirits hit rock bottom. Another interesting observation was the absence of ALL bird-eating raptors during this survey. Normally many Coopers Hawks, Sharp-shinned Hawks, Merlins and Prairie Falcons are observed. We saw one Prairie and one Coopers Hawk!

After visiting with many of our West Texas partners — ranching families owning the land where Aplomado Falcon releases occur — we learned a few interesting facts about the previous fall and winter. In their recollection, winter 2009 began early and as cold as they could remember in many years. Several large snow events occurred and persisted. Monsoon rains started early in the summer but by mid-July dried up or became very isolated. Temperatures turned very hot from July through September and, with a lack of growing season moisture, many grasses never produced seed, food for the many species of grassland birds. These events may have caused wintering grassland birds to move on. These grassland birds represent important prey items for Aplomado Falcons.

One scenario, believable to presume, might be that difficult conditions described during fall/winter 2009-2010 created a shift in wintering birds normally using these large desert grasslands, which in turn created a shift in “our” wintering Aplomados.

We will continue to carefully watch and see what develops between now and the next breeding season. An additional visit to this area three weeks later produced one additional Aplomado pair at a nest site and observation of the Baeza falcons incubating eggs. We hope they will continue to return and occupy every site from previous years.

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