66 The Ornithology of Chester County 



Departure Aug. 24 (190?) Sept. 26 (1889); 

 ave. 5 yrs. Sept. 7. 



1 1 6. Empidonax flaviventris Yellow-bellied Fly- 

 catcher. Rare transient ; probably more regular than 

 supposed, as it is mentioned by all our list makers. 

 Warren took four specimens Sept. 22-30, 1880, and 

 Montgomery secured three or four. The other rec- 

 ords are: Berwyn, Sept. 19, 1898 (No. 686, coll. 

 F. L. B.) ; Westtown, May 6, 1904 (Linton), and 

 Kennett Square, June 2, 1907 (Pennock). Barnard 

 informs us that it arrives May 8 to 14. 



117. Empidonax virescens Acadian Flycatcher, 

 "hick-up." Tolerably common summer resident ; in 

 late years becoming more localized and scarcely ever 

 found on the higher hills. Average date for com- 

 plete set of eggs at Berwyn, June 9. 



Berwyn : 



Arrival May 7 (1891-1895) May 26 (1900) ; 

 ave. 15 yrs. May 15. 



Common May 14 (1901-1905) May 31 

 (1910) ; ave. n yrs. May 22. 



It has been observed as late as Sept. 20. 



1 1 8. Empidonax trailli alnorum Alder Flycatch- 

 er. Rare transient. Dr. Michener of course follow- 

 ed Baird in calling this species E. trailli Traill's Fly- 

 catcher, and appears to be the only one, with the ex- 

 ception of Dr. Warren; who has obtained it in the 

 county. There are no recent records. 



119. Empidonax minimus Least Flycatcher, "che- 

 bec." Tolerably common transient. 



Berwyn: 



Vernal arriv. Apr. 28 (1915) May 7 (1917) ; 



