508 COLYMBIDE 
AVERAGE MEASUREMENTS. 
TOTAL LENGTH «.: a ae 1 DO dele 
WING Us, hats me ae elie 
BEAK ae ane is ye ot Pee 
T’ARSO-METATARSUS Bats sit | OR 
EGG ae wae co =. 90> SU anime 
BLACK-THROATED DIVER. Colymbus arcticus (Linneus). 
Coloured Figures.—Gould, ‘ Birds of Great Britain,’ vol. v, pl. 
44; Dresser, ‘ Birds of Europe,’ vol. viii, pl. 627; Lilford, 
‘Coloured Figures,’ vol. vi, pl. 46. 
Though this Diver may be regarded as an annual winter- 
visitor, it 1s much rarer than either the Great Northern or 
the succeeding species. Old males with their handsome 
velvety-black throats and richly variegated upper-plumage 
are not often seen.’ It is not improbable that immature 
individuals of this and the next species are often con- 
founded, as they resemble each other in plumage; the Black- 
throated Diver is, however, the larger bird. Exceptionally, 
it wanders southward along the Knglish coast visiting the 
Channel. In the ‘ Zoologist’ for 1903, p. 277, Mr. Gordon 
Dalgliesh states that on May 10th, 1903, an emaciated 
immature male was picked up dead on the beach near 
Cobo, in Guernsey, this being the second specimen recorded 
from that locality. 
Along parts of the Scottish coast it occurs all the year 
round, nesting in several counties of the mainland as well as 
in the Orkneys and Hebrides. It has increased in North 
Uist of late years, since the practice of robbing the eggs has 
been checked (Harvie-Brown, ‘Avifauna Of The Outer 
Hebrides,’ 1888-1902; Ann. Scot. Nat. Hist., 1903, p. 21). 
The Black-throated Diver has been recorded from the 
ereater part of the Irish coast; while it has been taken 
1 In the ‘ Zoologist’ for 1877, p. 8329, Mr. Warren records seeing this 
bird in full nuptial dress at the mouth of the River Moy, Mayo coast; 
the late Dr. Cox observed it on the Dublin coast in nuptial plumage in 
May. It has also been noted in nuptial plumage about Belfast Bay 
by the late Sir R. Lil. Patterson 
