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BULLETIN 185, U. S. DEPARTMENT OF AGRICULTURE. 



Incidentally it may be remarked that the black-and-white warbler 

 is one of the very few migrants which arrive in Texas and Florida 

 before they appear at the mouth of the Mississippi. The van of 

 most species reaches southern Louisiana earlier than southern Texas. 



Fig. 11. — Distribution and migration of the Ross snow goose ( Chen rossi). This is apparently the only 

 species that breeds on the Arctic islands, migrates south in fall through the Mackenzie Valley, and when 

 it reaches the United States, instead of passing south and east to the Mississippi Valley, turns west- 

 ward, crosses the Rocky Mountains, and winters in California. (See p. 23.) 



The cliff swallow is another species with a slow migration schedule 

 (see fig. 6). It must start northward very early, since by March 10 

 it is already 2,500 miles from the winter home and yet averages only 

 25 miles a day for the next 20 days while rounding the western end 

 of the Gulf of Mexico. It more than doubles this rate while passing 

 up the Mississippi and Ohio River valleys. The crossing of the Alle- 

 gheny Mountains comes next, and there are only 200 miles of progress 



