112 THE MIGRATIONS OF BIRDS 



our southern coasts in April. In travelling north to 

 the northern boundary of the United States the 

 birds move at a rate of 30 to 35 miles per day, but 

 from that point north the speed increases tremen- 

 dously, as black-polls appear in a week's time in the 

 central Mackenzie Valley, and in another week 

 arrive in northwestern Alaska. It appears that some 

 at least must average 200 miles per day for the 

 latter part of the journey. The species requires 30 

 days to cross the thousand-mile interval from the 

 Gulf coast to southern Minnesota, and only a little 

 more than half that time to traverse the 2,500 miles 

 that separate that point from the extreme limit of 

 its range in Alaska. 



From the same source may be taken some inter- 

 esting data on the spring movements of the robin. 

 In the east, migrant robins come north at a leisurely 

 rate, travelling through New England with the slow 

 advance of spring, so that to their northern breeding 

 limit in Newfoundland they average only 17 miles 

 per day. In the west, the western form of the robin 

 winters north into British Columbia and has to per- 

 form only a short migration to pass into Alberta and 

 Saskatchewan, to which it moves at an average 

 advance of only 8 miles per day. In the interior, the 

 eastern subspecies moves from its winter range 

 north to central Minnesota at the rate of 13 miles 

 per day, a rate that is doubled in the course to south- 



