30 The Ornithology of Chester County 
9 66 
4. Gavia immer \.oon, “big diver,” “great north- 
ern diver.” Not common transient visitant, though 
it appears on all our county lists. Migration dates: 
Apr. 26 (1915)-May 30 (1909) and again Nov. 
14 (1908)-Nov. 25 (1909). A flock appeared in 
the Chester valley on Nov. 14, 1908, during a N. 
E. snowstorm, and a pair secured from a small dam 
on the Chesterbrook farm (Nos. 934 and 935, coll. 
F. L. B.); another female lingered on a pond a 
mile further up the Valley creek until Dec. 10, when 
it was found dead and in an emaciated condition 
(Burns, Wils. Bull., 65, 215, and 66, 18). Under 
similiar circumstances ancther catastrophe occurred 
Nov. 25, 1909; two birds were shot at Paoli, two 
at Lenape and one seen on a pond near Westtown 
(Redfield, Ibid., 70, 56). 
5. Gavia stellata Red-throated Loon. Straggler. 
A female (No. 988, coll. F. L. B.) shot on Trotter’s 
dam, near Berwyn, Nov. 15, 1911; 1s the sole 
county record (Burns, Auk, xxxli, 1915, 225). 
6. Larus argentatus Herring Gull, “‘gull,” “sea- 
bird.” Rare transient and winter visitant. The 
following are all the records known to me: Central 
Chester Co., five noticed flying high overhead, even- 
ing of May 11, 1890 (Stene, Birds E. Pa. and N. 
J., 43) ; Berwyn, flock of sixteen going west at noon, 
Feb. 19, 1902, and Valley Forge, a single one on the 
Schuylkill, Jan. 6, 1902 (Burns MS.); and Ber- 
wyn, two on Apr. 1, 1908 (Redfield, Cass. xii, 53). 
7. Larus delawarensis Ring-billed Gull. During 
a severe storm from the west, Mar. 28, 1911, a crip- 
pled straggler was captured on Greystone farm, East 
