Page 49 - Design in Nature

Old feathers of birds are replaced with new
ones with different frequencies in different
species. The renewal of feathers is called
The
moulting, which happens before migration.
feather
of a
seagull
Feathers on the head,
body and wings protect
the birds from moisture The wing
and cold. They also help feather of a jay.
in the bird's soaring in
the air. Feathers on
the side cover the
delicate skin
that helps
regulate body
temperature.

Due to the
curvature of the
wing, air pressure
on the upper
surface is weaker
than on the under
surface, which in
turn lifts the bird
into the air (bottom
The feather of a left). If the wing is
lovebird. curved, further
airflow at the top
increases the
pressure creating
a downward force.
This way the bird
stalls (right
bottom).

The wing of a goatsucker.
The wing of a falcon.

Yellow lines indicate the
curvature of the wing.