Bonaparte's Gulls are in
the order Charadriiformes which consists of gulls,
terns, alcids and sandpipers. They are in the family Laridae which groups them together with Gulls. These
gulls are very petite, almost tern-like as they are 13.5
inches (34 cm) in size with a 33 inch (84 cm) wingspan.
Bonaparte's Gulls are not sexualy dimorphic which means that
both sexes look alike. Adults have a black head during
the breeding season and black ear patches during the
winter season. They have white crescents above and below
Their breast, neck, belly and
tail are all very white and they have a pale gray back
and upper wings. Their primaries also have black tips
that create a black trailing edge when they are flying
and black wingtips when they are at rest. Bonaparte's
Gulls take 2 years to become adults. At first they
appear to be brown which will
rapidly fade away. A juvenile's head and body will look
like an adult's during the winter season. They will have
a white tail with a black band at the end.
These gulls spend the breeding season
in Alaska and western and central Canada. During the winter months,
Bonaparte's Gulls are found in southern United States, parts of
Mexico and Cuba. During a mild winter they can be found around the
Great Lakes. Bonaparte's Gulls prefer being near water in places
such as: ocean bays, coastal waters, sewage outlets, wet meadows and
mudflats. The diet of Bonaparte's Gulls
consists mostly of terrestrial invertebrates, though they will eat
aquatic invertebrates as well. During migration they will eat mostly
fish, shrimp and other crustaceans. When foraging, they take items
from the surface of the water or just below while floating or
swimming in the water. When they are foraging for fish they will
drop from a high height in the air to the water.
Not much is known about
the breeding biology of Bonaparte's Gulls. They are
believed to be monogamous with one brood per year. It is
thought that both the male and female will construct the
nest which is usually located in abandoned tree nests.
They place the nest on a branch close to the trunk of
the tree or sometimes it is near the ground. The female
will lay about 3 buff eggs that are marked with brown.
It is believed that both sexes incubate the eggs for the
24 day period. The development of the young is
semiprecocial which means they are mobile, fed and
remain at the nest. Both parents will care for the young
until they are ready to fledge.
WHERE TO FIND THEM
Bonaparte's Gulls can be seen on the
Niagara River and around Lake Erie during temperate winters in