Despite
appearances, this fledgling has enough adult
feathers to retain the small satellite tracker.Photo:
Barbara Wienecke
Unlike ducks and swans, which take their
young to the water and show them how to
forage, penguin parents simply abandon their
chicks when they are about five months old.
The fledglings become very hungry and eventually
leave the colony to find open water. When
they do, they have to learn quickly what
and how to hunt.
For many years researchers
have wondered where juvenile emperor penguins
go once they reach the ocean. Do they stay
near the colonies, or do they find a good
foraging area and stay there? Now that instruments,
such as satellite trackers, are small enough
to be deployed on young penguins, we can
follow them on their first trip to sea and
find answers to these questions.
In December 2006 we
deployed 10 satellite trackers on fledgling
emperor penguins at the colony at Auster,
about 54 km east of Mawson station. The
colony, which comprises around 11-12 000
breeding pairs, had split into six different
'suburbs' that were up to 1.5 km apart.
When choosing our 'volunteers'
we wanted the fattest ones because they
had the best chance of survival. We also
needed fledglings with proper adult feathers,
not down, so that the satellite trackers
would remain in place once glued to their
back.
Before deploying the
satellite trackers we weighed each fledgling
to ensure it was fat enough. On average,
our volunteers weighed nearly 16 kg; the
satellite trackers only weighed 92 g and
were powered by two AA batteries. To conserve
power the trackers were programmed to transmit
data only four hours in 48.
Upon departing the colony
the fledglings had to cross nearly 50 km
of fast-ice and could not feed for several
days until they reached open water. Ten
youngsters stayed in the colony for three
to eight days after we left. Most of them
then started to head north towards the ice
edge. One of the young birds walked towards
the continent for nearly two days before
it realized that it was going the wrong
way. It turned around, went back to the
colony and then followed the others.
This map shows three
of the longest tracks recorded of young
emperor penguins on their first foraging
trip, during the Auster study in 2006-07.Photo:
Barbara Wienecke & AADC
Once they reached the edge of the fast-ice
the young emperor penguins had 200-300 km
of pack-ice in front of them. It was remarkable
to see how they moved through it, heading
directly north for the deep oceanic waters
of the Southern Ocean. Some of them spent
a considerable time north of 60°S. For
example, Fledgling 2 was tracked for 166
days and spent 76 of those north of 60°S.
The fledglings dispersed
over nearly a quarter of the Southern Ocean
in their first six months at sea. The eastern-most
position was at 93°E and the most westerly
position reached was at 7°E – over 2300
km from their birth colony! The total distance
traveled by one individual was nearly 7000
km.
But the story doesn't
end here. Emperor penguins are three years
of age, or older, when they first return
to their colony to breed. Our research has
given us a glimpse into their whereabouts
for the first six months after leaving the
colony. We still need to find out where
they spend the other two and a half years.
To do that we need to repeat the tracking
studies at Auster and adjust the transmission
time of the satellite trackers so that we
will be able to follow the young penguins
for much longer than six months. Over the
coming years we also plan to go to other
colonies and examine what young emperor
penguins do in other parts of Antarctica.
+ More
Rare visit to remote
Southern Ocean territory finds changes
15 January 2009 - The
Australian Antarctic Division has released
some rare pictures of Australia's remote
World Heritage listed Territory of Heard
Island and McDonald Islands (HIMI), located
in the Southern Ocean some 4000 km south-west
of Western Australia.
The Australian Antarctic
Division recently visited the islands on
the research ice-breaker Aurora Australis
and discovered visible changes which reflect
the highly dynamic HIMI landscape.
In the most obvious
change, a sand spit at the eastern end of
Heard Island had been inundated by the ocean
creating an "island" of what satellite
images from early last year showed to be
a section of land hanging on by a thread.
"It's a very dynamic
landscape, being home to two active volcanoes,
and its Southern Ocean isolation means visits
are rare," Heard Island expert Ewan
McIvor said. The Australian Antarctic Division's
last major expedition to the island was
in 2003/04 when significant glacial retreat
was recorded at Brown Glacier.
"Satellite imagery
has been showing the islands are constantly
changing. In 2004 remote sensing showed
volcanic activity on McDonald Island, some
44 km west of Heard Island, had doubled
in size from about 1 square km to 2.5 square
km.
"While weather
conditions prevented us getting any pictures
of the changed McDonald Island this visit,
it was very interesting to see the changed
landscape in the area of Heard Island known
as Elephant Spit. At our last visit this
still joined to the mainland," Mr McIvor
said.
The Australian Antarctic
Division manages the islands and 65,000
square kilometre marine reserve which lie
in the direct path of the "furious
50s", and are a technically challenging
and expensive place to visit. The dynamic
environment and the minimal modification
from human visitors makes Heard Island an
important location for Australian climate
change research.
During the brief but
valuable visit, the Australian Antarctic
Division expeditioners were able to complete
some aerial, ship-based and terrestrial
photographic surveys to detect environmental
change; inspect some of Heard island's heritage
sites; check and maintain scientific equipment,
and make sure refuge huts were still sound.
The Aurora Australis was also able to collect
further bathymetric data to improve charting
in the region.
The information collected
will provide important insights into the
status of Heard Island's glaciers, lagoons,
ice-free areas, vegetation and wildlife
colonies, and will contribute to AAD's responsibilities
for monitoring and managing this unique
and spectacular southern outpost. Information
collected will feed into an AAD project
currently underway to develop computer analysis
techniques to detect environmental change
at HIMI from satellite images.
+ More
Lessons learned from
devastating effects of cat eradication on
Macquarie Island
13 January 2009 - Research
by Australian Antarctic Division scientists
published today in the British Ecological
Society's Journal of Applied Ecology has
used World Heritage-listed Macquarie Island
as an example to illustrate the importance
of taking a comprehensive approach to management
of invasive species in natural environments.
Decades of conservation
effort was compromised on Macquarie Island
when a feral cat eradication program from
1985 to 2000 led to unintended and unplanned
consequences.
Terrestrial ecologist
Dr Dana Bergstrom said that the program,
while well-intentioned, resulted in widespread
ecosystem devastation when cats were eradicated
and rabbit numbers exploded.
"Cats were introduced
to Macquarie Island in about 1820 and rabbits
about 60 years later in 1878. By 1960, grazing
by rabbits was having very destructive effects
on the native vegetation," said Dr
Bergstrom.
Vegetation along Finch
Creek, Macquarie Island in 2001 showing
the tall lush native plant community, mostly
unmodified by rabbit grazing. Photo: Kate
Kiefer
"Management of
rabbits commenced in 1968 with the introduction
of the European rabbit flea (vector of the
Myxoma virus) followed in 1978 by release
of the Myxoma virus. Rabbit numbers peaked
at 130,000 in 1978 but eventually dropped
to about 20,000 and within 8-10 years the
island vegetation had recovered substantially.
"With fewer rabbits
to prey on, the cats switched to native
seabirds and by the mid 1980s were having
significant detrimental impacts on seabird
populations. Cat eradication commenced in
1985 and the last cat was killed in 2000.
Since then rabbit numbers have increased
rapidly and have substantially altered large
areas of island vegetation," she said.
Using Macquarie Island
as an example the paper suggests that the
nature of conservation funding, which typically
limits agencies to step-by-step eradication
programmes rather than more comprehensive
approaches, is often a problem. Funding
of larger but more holistic conservation
measures, as opposed to smaller, stepwise
measures may, in the long run be more successful
and cost effective.
A new strategy for Macquarie
Island is currently underway to eradicate
rabbits, mice and rats simultaneously at
a cost of approximately $24 million to be
met equally by the Australian and Tasmanian
governments.
