The Ocean Beach Coastal Reserve area is the breeding colony
for one of the most amazing migratory birds in the world, the short-tailed
shearwater, Puffinus tenuirostris, also known as the Tasmanian
Muttonbird.
Each evening from October until April, thousands of muttonbirds (Short-tailed
Shearwaters) fly in from the sea, circle, land and return to their burrows.
Migration
About 23 million short-tailed shearwaters migrate annually from
their breeding grounds in Tasmania (over 80%) and southern Australia
to the Northern Hemisphere to breed, travelling as far north as
the Bering Sea.
These birds are perfectly adapted for long distance flying.
Their short bodies and long sickle-shaped wings, ideal for gliding,
enable them to glide almost effortlessly above the waters surface
and to make the annual return migration of 30'000 km to the Aleutian
islands, near Alaska.
By banking into the wind to gain height, the birds can cover up
to 600 km a day in a series of long glides, and save their energy
reserves.
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The birds arrive at their breeding grounds in Bass Strait
just as the water is warming up, and their food of small
fish and animal plankton is becoming abundant.
They spend 4 - 5 months feeding in the cold, plankton rich
waters.
The adult birds leave on their annual migration in early
April.
The fledgling chicks remain in the colonies for another
2-3 weeks, before making the long journey alone.
Whilst in their breeding grounds of southern Australia,
the shearwaters feed as far south as Antarctica.
The birds are often seen resting and feeding in large groups
at sea called "rafts". |
Breeding
Short-tailed shearwaters can live up to 38 years.
They breed in colonies, building a burrow about 1 metre long,
close to the surface.
They lay a single egg in late November.
Incredibly, 85% of all the breeding females lay within three days of each other.
Both parents incubate the egg, which takes about 53 days to hatch.
The chicks grow to about one kilogram, twice the size of their
parents.
Once the parents leave on their annual migration, the chicks are
no longer fed but live off a reserve of energy rich oil held as
fat reserves.
These incredible birds fly great distances to return to the same
burrow each year.
Shearwaters are very good swimmers, capable of diving to over 20
metres in pursuit of krill, squid and fish.
Click here to listen
to the young ones crying out for their parents
(file type: .wma, size: 54 KB).
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