. Bulletin. Natural history; Natuurlijke historie. ue , i;»». ll«RH Ai;«3,IJ» Figure 31. August 21-23, 1950, when the first movements of thrushes were recorded (cf. p. 71). it was light west on the 23d (115 thrushes) and light east the next morning (only 8 thrushes). It thus appears that, if winds were a factor, they were those at the surface, not at high elevations. Further evidence that wind has little effect is provided by the conditions ob- taining on August 25 (Fig. 27). Fresh west wind at the surface, north-north- west-18 at 2000-5000, and north-24 at 10,000 feet. Air currents
. Bulletin. Natural history; Natuurlijke historie. ue , i;»». ll«RH Ai;«3,IJ» Figure 31. August 21-23, 1950, when the first movements of thrushes were recorded (cf. p. 71). it was light west on the 23d (115 thrushes) and light east the next morning (only 8 thrushes). It thus appears that, if winds were a factor, they were those at the surface, not at high elevations. Further evidence that wind has little effect is provided by the conditions ob- taining on August 25 (Fig. 27). Fresh west wind at the surface, north-north- west-18 at 2000-5000, and north-24 at 10,000 feet. Air currents thus were stronger near the ground and at high altitude, yet no migrants whatever appeared. What of the great flight—650 thrushes—on the following morning? The weather map of 1:30 , August 26, shows a limited occlusion approaching. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peabody Museum of Natural History. New Haven : The Museum
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