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Western Sandpiper
Behaviour
Feeding, Hunting & Foraging Behaviour of the
Western Sandpiper
Western Sandpipers prey on marine
invertebrates that burrow in mud and sand beaches, and
among wracks of seaweed. They also eat diatoms and microscopic
life living on the surface of mud. Invertebrates that live in
the mud and sand are caught using a sewing method where the
bill is slipped rapidly up and down in the mud until a worm is
found, or picked from the surface. The prey animal is then
pulled from the mud and swallowed. Biofilm – the living matter
on the mud surface – is also eaten by Western Sandpipers by
dabbing the tongue on to the muddy surface and slurping it
into the mouth. During the breeding season, Western Sandpipers
on the Alaskan tundra use their tweezer-like bills to pick
emerging insects from plant stems.
Flight Patterns of the Western Sandpiper
Western Sandpipers fly with direct and steady wing beats while
on migratory flights. They can glide for short distances while
descending but most fly is steady and direct. Around the
foraging areas, flocks will take to the air in darting and
weaving formation to avoid attacks from falcons. Shorebirds
are capable of rapid turns in flight that to our eye appear as
one but video of flocks when slowed reveals that the birds
turn in sequence and occasionally collide. On the breeding
grounds, Western Sandpiper males hover in the air above the
territory to attract the attention of potential mates.
Aggressive, Defensive & Territorial Displays of
the Western Sandpiper
Western Sandpipers threaten by running at each other with the
tail held erect, the neck retracted and the bill pointed
horizontally at the opponent. These displays are seen
occasionally on the winter quarters and on migration, and
often on the breeding grounds. They also pursue one another
for long distances over the tundra. If a predator approaches a
nest, adult Western Sandpipers roll to one side as if the wing
is broken, flutter the wings and give a chirring sound to draw
the predator’s attention from the nest.
Courtship & Breeding Behaviour of the Western
Sandpiper
The breeding season begins in late May in western Alaska and
ends in July or August when the young depart to the south for
the winter. Adult males arrive on the breeding grounds first
often while snow is still on the ground. They establish a
territory where the females will lay eggs. The females arrive
soon after the males in late May or early June and the 24
hours of sunlight results in around the clock courting. To
court a female, males hover in the air for long periods
uttering a buzzing call. This time of year is full of activity
as males chase one another all the while attempting to lure a
female to mate with them. Most Western Sandpipers produce 1
brood per year but they will attempt to relay a
clutch if the first attempt fails early in the season. Many
pairs return to the same territory or close by in successive
years.
Western Sandpiper Nesting Habits
Shorebird biologists
estimated the world’s population to be about 3.5 million
Western Sandpipers making it the most numerous species on the
northeast Pacific Coast. The majority of these tiny birds nest
along the western shore of Alaska where biologists have
studied the
breeding biology in detail. The breeding range extends as
far north as Barrow in Alaska and a small number nest along
the extreme eastern Siberian shore in Russia. The nest is a
tiny cup about the size of a tea cup made of dried grasses and
plant stems hidden in the tundra vegetation. The reddish brown
with dark scrawl markings on the eggs match the dried and dead
stems of the tundra. The average clutch size is 4 eggs. Adults
feign a broken wing when an intruder approaches a nest or
flutter in front of intruders who get close to their eggs and
young. Both parents incubate the eggs which requires about 18
to 21 days. Eggs hatch into downy chicks with buff and
chocolate markings, dark brown irises and black legs. Their
mothers begin to depart the breeding grounds in mid June
leaving the care to their fathers. The young are highly mobile
within a few hours of hatching and they scamper off into the
tundra. As the chicks age, their downy feathers are replaced
with a juvenile plumage, their fathers begin to depart for the
winter quarters. As a result, the adult males pass south on
migration through British Columbia in late July ahead of their
young. By late July the first young depart Alaska and most
have gone by the middle of August.
Western Sandpiper Vocalizations
Western Sandpipers, like many of the small sandpipers, utter a
peeping call that has given rise to the colloquial name ‘peep’
for this group of birds. In a feeding flock, the peeping
sounds like busy office chatter but when disturbed by an
attacking falcon, it becomes a din of panicking, flapping
shorebirds. The territorial call is a buzzing sound. During
migration, individuals departing for a long flight utter a
‘wreet’ call that is likely used to enlist flock mates to fly
with them. Some sandpipers also shriek when captured which
draws the flock around for a second look.
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