Page 59 - Complete Birds of Britain and Europe (DK - RSPB)

DIVERS AND GREBES
Order Gaviiformes Family Gaviidae Species Gavia arctica
Black-throated Diver grey
nape

dark cap
ADULT barred or scaly, IMMATURE
narrow (SUMMER) brown-black white (1ST WINTER)
wings back flank patch scaly back
grey head
outstretched
head held low
bill held
level
spotted
ADULT (WINTER)
ADULT striped “necklace”
neck
(WINTER)
oval patch of white black throat
bars on each side
white breast
IN FLIGHT

n summer, few
Ibirds can match the ADULT (SUMMER)
exquisite patterning of the Black-throated Diver.
In winter, it is duller and harder to tell from a Great Northern or
Red-throated Diver, but the slightly bulbous head, slim, straight bill, FLIGHT: head low, outstretched, legs trailed;
and narrow body are distinctive, along with the greyish nape, paler narrow wings have slightly whip-like action.
than the back. Small parties of
Black-throated Divers gather in
coastal bays in summer. However,
this bird is generally solitary,
swimming low on the sea.
VOICE Wild, loud wailing notes
in summer; silent in winter. SUMMER GATHERING
NESTING Shallow scoop near Black-throated Divers gather in impressive groups,
water’s edge on island (or raft) in swimming close together with heads raised.
lake; 2 eggs; 1 brood;April–July.
FEEDING Dives long and deep NESTING ON RAFT
for fish, reappearing far away; Black-throated Diver nests are often subject to
slides evenly head-first into water flooding or left high and dry; artificial nest rafts
with barely a ripple. ensure greater breeding success.
SIMILAR SPECIES OCCURRENCE
Breeds on large lakes with small
chequered black head RED-THROATED DIVER islands in remote areas of
back winter, similar to adult N Scotland and Scandinavia. In
winter; see p.56
winter, more widespread but
whiter
face scarce on coasts of NW Europe.
Often in larger estuaries or broad
sandy bays; rare inland.
GREAT NORTHERN DIVER
summer, similar to adult Seen in the UK
summer; see p.58 J F M A M JJ A S O N D
Length 60–70cm (23 1 ⁄2 –28in) Wingspan 1.1–1.3m (3 1 ⁄2 –4 1 ⁄4ft) Weight 2–3kg (4 1 ⁄2 –6 1 ⁄2lb)
Social Small summer flocks Lifespan Up to 20 years Status Vulnerable
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