220 



MIGRATION 



while one-third fall between this and the extreme dates. This signifi- 

 cant relation is brought out clearly in the following table, which com- 

 prises migrants representative of different periods of variation in re- 



TABLE 6 



Species 



Record, 

 Years 



Extreme 

 Dates 



Average 

 Date 



Varia- 

 tion in 

 Days 



Stand- 

 ard De- 

 viation 



Average 

 Devia- 

 tion 



Average 

 Varia- 

 tion 



Birds 



Marsh hawk 



Yellow-bellied sapsucker. . 



Canada goose 



Chipping sparrow 



Ovenbird 



Black-throated blue war 



bier 



Black-poll warbler 



Plants 



Blue violet 



Columbine 



Yellow adder's-tongue. . . . 



34 

 39 

 40 

 45 

 43 



41 

 26 



28 

 28 

 26 



1/1-5/10 

 1 27-5/22 



1,4-3/31 

 3/13-3 1 

 4/3 -5/15 



4/25-5/20 



5/8 -5/27 



4/8 -5/8 

 5/5 -6/2 

 4/14-5/5 



3/8 

 4/5 



3 3 



4 3 

 5/4 



5/7 

 5/lg 



4/28 

 5/16 

 4/23 



130 

 116 



50 

 43 



26 

 20 



31 

 29 



32 3 

 16.6 

 17.3 



10.7 

 7.1 



4.6 

 5.1 



6.9 

 7.5 

 6.1 



22.6 

 10.4 

 12.1 



8.5 

 4.8 



3.3 



4.2 



5.1 

 5.6 

 5.1 



11 

 2.1 

 1.4 



4.9 



TABLE 7 



Irregularity of Spring Return in Palm Warbler and Cowbird 

 (From tables of Wood and Tinker: 1906-1930) 



Palm Warbler 



+ + 



+ + + + + + + 



+ + + + + + + + + 



Apr. 21 22 23 24 25 26 27 28 29 30 



+ + + + + + 



May 12 3 4 



6 



1913-14: April 26 



Cowbird 



+ 

 + + + 



+ + + + + 



+ + 



+ + + + 



Feb. 15-Mar. 9 10 11 12 13 14 15 16 17 18 19 20 



+ 

 + + + + + + + 



Mar. 21 22 23 24 25 26 27 28 29 30 31 



+ + 



Apr. 12 3 4 5 6 



1918-19: March 17 



