Common Terns are
shorebirds in the family Laridae which groups them
together with Gulls.
They are a smaller tern as they are 14.5 inches (37cm)
in size with a 30 inch (76cm) wingspan. Common Terns are
monochromatic which means that both males and females
look alike. They are fairly graceful and slim birds with
greatly forked tails. During the breeding season, adults
have red legs and an orange bill with a black tip. They
have a white face and a black cap with a medium-gray
neck, breast and belly.
Their back and upperwings are
back and they have a dark wedge on their outer primary
feathers. By late summer, their rump and tail are white and their outer
flight feathers
have dark edges. During the nonbreeding season, their
bill is mostly black and they have a black cap. Juvenile Common Terns have pale legs
and a pale bill that will become darker as they age.
Their forehead, foreneck, breast and belly are white.
Their wings are gray with brown tips and their tail is
short with black tips.
Photo: M. Noonan
Common Terns nest
colonially in tens to thousands. During courtship
displays, the male will strut and waddle with his next
fully extended, his bill pointed up, with his tail
cocked and breast expanded around the female. He will
present the female with nuptial gifts as part of a ritual, and will be
interrupted many times by a different male trying to
lure the female away. Common Terns are monogamous and
have one brood per year. Occasionally they will have 2
clutches, but the second is rarely successful.
The
mating pair will have a separate nesting and feeding
territory. The male will usually defend the feeding
territory. Both males and females will build the nest
which is usually located in sand shells or pebbles. It
is shaped by the body and lightly lined with grass and
seaweed. Occasionally the pair will not build a nest.
The female will lay 3 eggs that can range in color from
olive to buff to brown marked with brown. The third eggs
is usually the smallest and least likely to survive.
Both parents will share the responsibility of incubating
the eggs for the 21-27 day period.
The development of
the young is semiprecocial which means they are mobile,
fed and remain at the nest. Both sexes will care for the
young which are able to fly 26-27 days after hatching.
