100 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 
CWils, ‘Bull, 28) 75 5\) 20, (73) Pennock) tonked 
specimen at Kennett Square, Apr. 19, 1909. 
213. Oporornis formosus Kentucky Warbler, 
‘“Vellowbird.”” 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, 
1375 XM, 43'5': XIV, VO4s xv, 1455) xvil, 1S INortis 
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 
