DELAWARE VALLEY ORNITHOLOGICAL CLUB. 37 



ing the lowest point March 2-4, with a mean of 24° and snow 

 fall on March 4, 5 and 6. No migration was noted until the 

 8th when the snow had disappeared and flocks of Red-winged 

 Blackbirds passed north. A gradual rise culminating on the 

 18th brought many Fox Sparrows, Field Sparrows, Kildeers 

 and Flickers. 



A sudden fall brought the mean temperature to 32° on the 

 21st and more or less rain prevailed. In spite of this a marked 

 rise in temperature culminating on March 29 brought a flight 

 of Flickers, Field, Chipping and Vesper Sparrows. 



A marked warm wave on April 6 brought the Hermit 

 Thrushes and one on April 16 the Ruby-crowned Kinglets. 

 The great migration waves of the month however were on the 

 22d and 27th with but slight rise in temperature and cloudy 

 weather. The former movement consisted of House Wrens, 

 Thrashers, Yellow Palm Warblers, Barn Swallows, Chimney 

 Swifts and Towhees; the latter of Wood Thrushes, Catbirds, 

 Maryland Yellow-throats, Ovenbirds, and Black and White 

 Warblers. 



Then came a period of cold rain, the temperature rising again 

 by May 2, and an immense migration of Warblers, etc. on May 

 3 and 4 then rain until May 9 and the greatest movement of 

 the season on May 11, closing the migration. 



The fact brought out in last year's report, that birds moving 

 at the same time are affected in the same way by weather con- 

 ditions so that early migrants may be late and late migrants 

 early or vice versa, is clearly demonstrated by this year's record 

 as well as the fact that the time of arrival except in the early 

 migrants, which winter just to the south of us, does not vary to 

 any great extent. 



These facts may be seen by glancing down the appended list 

 in which the species are arranged in order of their arrival, the 

 dates being the average of eleven years' bulk arrivals at Phila- 

 delphia computed in the usual way. The -f- or — figures 

 represent the number of days that the 1912 dates were earlier 

 or later than the average. 



