lOO The Ornithology of Chester County 



Spring arrival — Apr. 14 (1912) — May 10 

 (1890) ; ave. 5 yrs. May 7. 



Spring departure — May 14 (1912) — May 30 

 (1907) ; ave. 3 yrs. May 25. 



212. Seiurus motacilla Louisiana Water-Thrush. 

 Rare summer resident. Warren has taken a few 

 specimens in summer (Bds. Pa., 1890, 295) ; Jack- 

 son and Ladd searched a ravine near Whitford, for 

 several seasons without locating its nest, though a 

 pair of this elusive species was present. A pair 

 inhabited an extensive and well watered tract of 

 woods near Daylesford, for several years, and I 

 found one young bird apparently just out of the 

 nest, June 3, 1899; a pair was present on May 6, 

 1906 and May 8, 1909, but the nest was not found 

 (Wils. Bull., 28, 75; 59, 73). Pennock took a 

 specimen at Kennett Square, Apr. 19, 1909. 



213. Oporornis formosus Kentucky Warbler, 

 "yellowbird." Common summer resident, often 

 rather abundant in the vicinity of Birmingham meet- 

 ing house. West Chester and Berwyn; formerly 

 quite rare (Cf. Rhoads, B. N. O. C, iv, 234; Hall, 

 Jackson, Norris, Jr., Norris, Sr., Orn. and OoL, ix, 

 137; xii, 43; xiv, 104; XV, 145; xvii, i; Norris, 

 Jr., Nid. i, 165; and Burns in Chapman's Warb- 

 lers N. A., 237). Nidification commences about 

 May 25 ; in thirty instances the average date for a 

 complete set of eggs is June 3. 



Berwyn : 



Arrival — May 3 (1896-1900) — May 16(1917) ; 

 ave. 17 yrs. May 8. 



Common — May 9 (1904-1910) — May 22 



