ML75078961
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観察結果の詳細
A flock of Red Crossbills continued in the stand of loblolly pines near Cowboy Court across TX-144 from Midway RV Park and Storage in Hood County, Texas on the afternoon of 11-12-2017. Many thanks to Ed Wetzel and Greg Cook for alerting us in regard to the presence of these birds that are usually very uncommon in Texas. Male and female Red Crossbills were observed, identified and documented by photograph based on their unique crossed bills, their color (red for male and greenish-brown for female) and overall appearance and behavior. None of the crossbills observed had white wingbars. The crossbills spent most of their time high in the canopies of the loblolly pines, feeding on the nuts in the pine cones. I was able to obtain better photographs when some of the crossbills flew down to a hackberry tree adjacent to a small pond by Cowboy Court, alighting in the tree briefly prior to flying down to the pond to drink. A Red Crossbill's bill is specialized for removing pine nuts from underneath the scales of pine cones. Like the crocodilians, the muscles that close the bill of the Red Crossbill are stronger than those that open the bill. When the Red Crossbill inserts its slightly opened crossed bill underneath the scale of a pine cone and closes its bill, it is able to raise the scale and remove the pine nut under the scale. According to the TOS Handbook of Texas Birds (Lockwood & Freeman, 2nd Ed., 2014),the Red Crossbill is a "rare resident in the Davis and Guadalupe Mountains and an irregular winter visitor in the northern two-thirds of the state. There have been several small invasions that have pushed into the northern two-thirds of the state. A major invasion in the winter of 1996-97 produced many first local records. including in the Pineywoods (Schaefer 1998), where Red Crossbills were found in 10 counties. Following that winter incursion, Red Crossbills remained through the summer in many locations and were strongly suspected of breeding in the Pineywoods and Taylor County. Another major invasion occurred in the winter of 2011-12 with birds found in various areas of the High Plains and Trans-Pecos and flocks located as far east as Hood, Kaufman and Wilbarger Counties.." The opinion from Cornell, after analyzing recordings of the calls of the flock of Red Crossbills present on Nov. 11 (Sat.) before we were there on Nov. 12 (I did not make the recordings), was that, based on the calls, the flock was about 85% Type 2 Red Crossbills and 15% Type 4 Red Crossbills.
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