66 The Ornithology of Chester County 
Departure—Aug. 24 (1907)—Sept. 26 (1889) ; 
ave. 5 yrs. Sept. 7. 
116. 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. 11 yrs. May 22. 
It has been observed as late as Sept. 20. 
118. 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); 
