V.,l XXX 



1913 '| Brora, Bird Migration Record* "J William Bartrarn out 



I have computed the average of the earlie il arrival date furni ihed 

 b; an; oi tb i obsei ei for each year, and also a 'bulk arrival' 

 daft b i plained above, for comparison with Bartram's a erage 

 date of arrival for 1802 1822, and the three letsofdate an gi en 

 in t In- accompany ing table. 



\\ i ihould expect most of the date of an; tingle obser erofour 

 corps to fall between the two dates given and in lixteen ca • Bai 

 tram' date do <>, indicating that there has been no change in 

 the time of arrival during a century, in four cases they are later 

 than the date of 'bulk' arrival Kingfisher 5 daj ., Chimm 

 Swift u (\;r, ,, Bobolink I day, Towhee l day, The Kingfisher i, 

 .•in irregular ipecies often w intering here w Kile Bartrarn' . dates foi 

 the Chimney Swift are in all probability inaccurate tince Barton 



•' below) gi e April 23 which agre< ivell with our recent records. 



I i i pecie ''ii Bartram's list are earlier than ouj a erage first 

 arrival Hummingbird 3 da> , Orchard Oriole I da; , Baltimore 

 Oriole I da; , Red eyed Vireo '■'> days, Vellow Warbler2 daj Of 

 these the Vireo is probably too early as Bartrarn <li<l nol know 

 either the Solitary or Vellow-throated Vireos and may Im- e 

 confu ed them with it. Por the Vellow Warbler lii location ■ •> 

 peculiarly favorable while for the Hummingbird and Orchard 

 Oriole the recent records are not to full as mighl be and the dates 

 computed are probably late. 



Prof. \\ . W < 'x.l.' : ha recentl; made a comparison of the date 

 of arrival given bj Dr. Benjamin Smith Barton in his 'Fragment 

 of Natural History' for 1799, with his own computations from 

 the recent records of the U.S. Department of Agriculture for the 

 vicinity of Philadelphia. It is interesting to compare these dates 

 with those jusl given as Barton's observations and Bartram's 

 were undoubtedly made in almost the tame ipot. We find thai 

 in fifteen ipecie ■■•■ hich occur j n both Ii it i, the date of arrival i i the 

 lame in onlj one in even cases Bartram's date are biter than 

 Barton's bj from one to nine da; a erag< fi - da; while in 

 i 'M '.i i the; are earlier b) from two to even days (a era 

 lour days). 



Prof. ( coke's computed dates for arrival al Philadelphia for 



' I 0l»', 191 ' |i. 7. 



