Page 12 - Complete Birds of Britain and Europe (DK - RSPB)

INTRODUCTION

ANATOMY

lthough there is a huge diversity in shape, Their bones are like ours,but the proportions are
Asize, and outer appearance,all birds have a very different.For example,the wing bones are
similar internal structure.They are vertebrates, like a human arm;the “inner wing”equivalent to
so have a jointed internal skeleton with two our forearm,and the “outer wing”like the bones
forelimbs and two hindlimbs,just like fish, of our hand.What makes them unique is that
reptiles,and mammals – including humans. they are the only animals with feathers.

lightweight skull CROSS-SECTION OF BONE
with air spaces Birds need to weigh as little as
possible in order to be able to fly.
fused spine
To keep their skeletons light yet
jawbones strong, the bones are honeycombed
have a horny with airways.
sheath
tail
wide clavicles
or “wishbone” UNDERSIDE
The wing feathers form several tracts
sternum or breastbone hidden attached to different bones. The outer
forms a keel, to which knee joint wing is formed with long flight feathers
breast muscles attach called the primaries while the inner wing
ankle joint
is shaped by the back flight feathers called
toes and claws
secondaries. These large quills are covered
BIRD SKELETON at the base by several rows of smaller
The spine is fused solid with no feathers, known as “coverts”. At the
flexibility except in the neck and tail. base, a triangle of feathers called the
The skull is lightweight and the jaws axillaries fills the “wingpit”. The
extend into the bill. The breastbone is head, belly, breast, and flanks
a deep keel on birds with large flight are covered by shorter,
muscles, but shallow on gliders. The less flexible feathers. axillaries
exposed “leg” is like a human’s foot.
flanks breast
primaries;
primary coverts outermost
“notched” bill
to create
alula (bastard slots
wing)
under tail
greater coverts coverts
belly
median coverts
secondaries vent foot
lesser coverts
upper tail
marginal
coverts coverts
hindneck
nape
TOPSIDE
crown
There are several rows of feathers
forehead along the inner half of the spread
wing: the marginal coverts, lesser
chin coverts, median coverts, and greater
throat coverts (simple enough, as they get
larger towards the back), and the trailing
edge is formed by the secondaries. The
tertials outer half repeats the pattern but the coverts
rump at the base of the primaries are restricted to a
scapulars patch on the “wrist”, with the addition of the
tail alula or bastard wing. At the base of the
mantle wing, the shoulder feathers, or scapulars,
form an obvious patch each side of the back.
10