Page 21 - Complete Birds of Britain and Europe (DK - RSPB)

PLUMAGE

ABERRATIONS AND VARIATIONS
Not all birds are perfect examples of WEAR AND TEAR
their species. Some are “aberrant”, This gull has gaps in its wings and tail.
because of some genetic deficiency. Some feathers have been shed and
“Albinos” are all-white,“albinistic” not yet replaced while others
birds are partly white, and “leucistic” are simply worn and faded,
birds look pale and washed out through which alters the
lack of pigment.“Melanistic” individuals wing pattern.
have too much pigment, and look WHITE BLACKBIRD
exceptionally dark. Other variations The normally black Blackbird
are a normal part of everyday life. For quite often throws up partly
example, feathers naturally bleach and white variants. This is a minor
fade in the sun and wear away at the tips genetic flaw; such birds are
during the course of months of wear. “albinistic” or “partial albinos”.

MOULTING
Moult is a well-ordered process. Each
worn feather is pushed out when a new
one grows through the skin at its base. HIDING AWAY
The new feather begins as a tiny bump Stripes on the front of a
– a “goose bump” – on the skin and Bittern make it extremely
grows as a shiny sheath that bursts open hard to see when it
stretches upright in the
at the tip to reveal the soft webs. On dead reed stems of winter.
most birds moult is not easy to see, but It is much easier to spot
on some larger ones it is possible to in the summertime.
spot gaps where feathers are missing.
Old feathers usually become paler and
pure colours, such as grey and green,
tend to turn browner as the feathers
age.These contrasts can sometimes be
seen on a bird at close range, or in a
photograph, but most studies of moult
rely on trained bird ringers, who catch
birds and examine their stage of moult
before releasing them.
BAR-TAILED GODWIT IN MOULT
The stretched wing reveals five old outermost
primaries (the longest wingtip feathers), a gap where
several have been shed, and a few new inner ones.
Some missing wing coverts also reveal spaces in the
neat rows of white feathers. This is the complete
autumn moult, so this bird is changing from
summer to winter plumage, probably in
August or September.

CAMOUFLAGE
A major function of plumage pattern is to break up the
shape of a bird so it is hard to see. Both predators and prey
use camouflage: one to get close to its meal, the other to
avoid detection. For example, Oystercatcher flocks confuse
predators with a mass of dazzling white patches.

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