Common Terns are
shorebirds in the family Laridae which groups them
together with Gulls. They are smaller, common terns.
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, the outer 5 primary feathers
are dark because the primary pattern darkens with wear.
Their rump and tail are white and their outer retrices
have dark edges. During the nonbreeding season, their
bill is mostly black and their black cap starts from the
eye to the crown and then extends from the eye to the
nape of the neck. 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.
The breeding range of the Common Tern
extends through most of eastern and central Canada, the eastern
seaboard and parts of the Great Lakes Region. They are found in
southern Peru and northern Argentina during the winter. Populations
of Common Terns are declining around the Great Lakes Region because
they are losing nest sites due to the growing Ring-billed Gulls
populations and rising water levels. Common Terns can be found
surrounding lakes, oceans, bays, ponds and small islands.
Fish compromise 90% of the Common
Tern's diet, with the rest being crustaceans and insects. They
forage by dropping from the air and diving into the water after
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
also feed the female 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.
Where to see
Common Terns can be seen around the
Niagara River and Lake Erie, though their numbers are decreasing due
to lack of nests because of expansion of Ring-billed Gulls.