670 REPORT OF THE HARVARD AFRICAN EXPEDITION 
No doubt this (with other species of terns and gulls) occurs on the Liberian 
coasts more commonly, but the only instance recorded is of a male taken Febru- 
ary 10, 1911, at Subono by Lowe (Bannerman, 1912, p, 258). 
Chlidonias nigra nigra (Linné). Black Tern 
Sterna nigra Linné, Syst. Nat., ed. 10, vol. 1, p. 187, 1758: Sweden. 
Small, length 9.5 inches; head and neck black; back, wings, and tail light gray; lower side 
slaty gray, anal region white; bill black, feet reddish. In winter, forehead, neck, and lower surface 
are white, only the occiput and nape are black. Breeding in southern and central Europe and 
western Asia; winters south in West Africa to Loango. 
This is probably a wintering bird, but Biittikofer (1885, p. 250) on August 15 
found a large flock, all apparently immature, near Robertsport, from which he 
secured twenty birds. In a later paper (1888) he mentions large flocks seen near 
Fish Town, Grand Bassa, on the sand flats before the mouth of the Bissaw River, 
but does not give the date. 
Rhynchops flavirostris Vieillot. African Skimmer 
Rhynchops flavirostris Vieillot, Nouv. Dict. d’Hist. Nat., vol. 3, p. 338, 1816: Senegal. 
Size of a tern, about 16 inches long; lower mandible longer than upper and very compressed; 
top of head, neck, back, center of rump and wings, blackish brown; forehead, sides of head, under 
side, and lateral under tail-coverts white; primaries white-tipped; bill reddish, tipped with yellow, 
feet orange. Senegal and Egypt south to Orange River, coasts and rivers. 
This bird may nest occasionally in suitable places on the Liberian coast; 
Biittikofer is the only authority for its occurrence, however. In the summer 
of 1881 he saw them, always in pairs, at various times on the coast near Robert- 
port, and on August 17 a pair in full breeding plumage. Later, on September 26, 
he saw a pair with bills not fully developed. 
COLUMBIFORMES 
COLUMBIDAE Pigeons 
Columba unicincta Cassin. Afep Pigeon 
Columba unicincta Cassin, Proc. Acad. Nat. Sci. Philadelphia, 1859, p. 143: Ogowe River, W. Africa. 
Length about 13 inches; head and neck light gray, center of throat white; back and wing- 
coverts slaty, pale edged, rump and upper tail-coverts slaty gray, breast pale vinaceous, sides light 
gray; center of abdomen and under tail-coverts white; tail slaty banded with white. Liberia to 
Ogowe. 
This is the only species of typical Columba occurring naturally in Liberia, 
where, however, it seems to be exceedingly rare, and so far as known, is probably 
a bird of the high forest. We saw nothing of it, and the only records are the two 
of Biittikofer, the one a female taken at Soforé Place on the large, thickly-wooded 
island of Alin, and figured by him in colors (Biittikofer, 1885, p. 226); the other 
a single bird brought in by a native at Hill Town, January 4, but so badly in- 
jured that it was not preserved (Bittikofer, 1888, p. 97). 
