in that region until 2 or 3 months after they were banded. Probably 

 the fastest flight over a long distance for one of these little ducks was 

 one made by a young male which traveled 3,800 miles from the delta 

 of the Athabaska River, in northern Alberta, Canada, to Maracaibo, 

 Venezuela, in exactly i month. This flight was at an average speed 

 of 125 miles per day. The greatest migration speed thus far recorded 

 for any banded bird is that of a lesser yellowlegs banded at North 

 Eastham, Cape Cod, Mass., on August 28, 1935, and killed 6 days later, 

 1,900 miles away, at Lamentin, Martinique, French West Indies. This 

 bird traveled an average daily distance of more than 316 miles. 



It seems certain that migratory journeys are performed at the normal 

 rate of flight, as this would best conserve the strength of the birds and 

 eliminate the fatigue that would result from effort required for great 

 speed. Migrating birds passing lightships and lighthouses, or cross- 

 ing the face of the moon, have been observed to fly without hurry or 

 evidence of straining to attain high speed. 



The speed of migration also is demonstrated by the dates of arrival, 

 particularly during the spring movement. The Canada goose affords 

 a typical example of regular, but slow migration. Its advance north- 

 ward at this season is at the same rate as the advance of the season 

 (fig. 4). In fact, the isotherm of 35° F. appears to be a governing 

 factor in the speed at which these geese move north, and over their 

 entire trip the vanguard follows closely the advance of this isotherm. 



Few species perform such regular migrations, many waiting in their 

 winter homes until spring is well advanced and then moving rapidly 

 to their breeding grounds. Sometimes this advance is so rapid that the 

 later migrants actually catch up with species that for a month or more 

 may have been pressing slowly but steadily northward. 



One of the best examples of rapid migration is found in the gray- 

 cheeked thrush. This bird winters in Colombia, Ecuador, Peru, Vene- 

 zuela, and British Guiana and does not start its northward journey 

 until many other species are well on their way. It does not appear in 

 the United States until the last of April — April 25 near the mouth of 

 the Mississippi, and April 30 in northern Florida (fig. 5). A month 

 later, or by the last week in May, the bird is seen in northwestern 

 Alaska, the 4,000-mile trip from Louisiana having been made at an 

 average speed of about 130 miles a day. 



Another example of rapid migration is furnished by the yellow, or 

 summer, warbler. Coming from the Tropics, the birds reach New 



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