Hello Birders
Please find following an update relating to the Banded Stilt threat
caused by Silver gulls at Lake Eyre in South Australia. Previous notes
were posted here on the 07,10 & 15/07/2000.
During the period from Monday 17 July, to Saturday 22 July 2000, the
South Australian Government through their wildlife management agency,
National Parks and Wildlife (NPW) recommenced a project to protect
Banded Stilts breeding at Ibis Island, Lake Eyre from attacks on the
colony by Silver Gulls. Gull attacks on Banded Stilts ceased soon after
the control work resumed, however up to 50 gulls were found to move in
most days and this required constant follow up action.
The good news is that on Monday, Banded Stilt chicks were observed
nestled under adults near the north eastern corner of the colony
indicating that hatching commenced during the previous night (the
evening of the lunar eclipse). Throughout the week, clutches of stilt
chicks emerged in ever larger numbers with separate waves of synchronous
hatching spreading south within the colony. By Friday, more than 60% of
the nests had chicks and it appeared that most scrapes at the southern
end of the colony contained eggs chipping out. This event is now
proceeding without much harassment from Silver Gulls.
At about 10.50 hrs (CST) on Wednesday, the first two groups of Banded
Stilt chicks emerged from samphire shrubs at the west side of the
colony. Appearing as highly mobile white fluff balls accompanied by
several chattering adults, they moved in short rapid almost dotterel
like bursts of motion across the 100 metres of muddy shoreline to the
surface of the lake. Almost immediately these chicks commenced feeding
with the adults while slowly moving west out over the shallow water.
By about 15.00 hrs young stilts accompanied by a few adults were moving
onto the lake at a rate of about 60 chicks per hour (CPH) and had
increased to nearly 400 CPH by 11.00 on Thursday morning. The rate of
departure continued to increase during the warmer period of the day and
ceased during the evening. By Saturday morning, 22 July large masses
of chicks were departing in compact groups of more than 60 each, and
accurate counting was almost impossible.
Meanwhile daily observations from the air indicate that chicks are
spreading out across the lake to the south and west moving at a speed of
about 3.5 km per day. By Saturday morning, some chicks were observed up
to 9.1 km from the colony.
However a problem now rapidly emerging is that the Banded Stilt chicks
are moving directly towards the largest known Silver Gull concentrations
at Lake Eyre. These Silver Gulls (20,000 plus nesting pairs) are
currently incubating eggs and many observers, including the author of
this report, fear that the gulls may display a more aggressive and
competitive feeding behaviour when their eggs hatch.
So far this third Banded Stilt breeding attempt at Lake Eyre appears to
be a success. There is an average of about 3 chicks per clutch getting
to the lake and mostly without harassment from Silver Gulls. This
improved situation is due in no small part to the rapid and direct
intervention of the NPW Silver Gull control team, however the powers at
be will not agree to extending the exclusion area to more than a 10 km
radius of Ibis Island unless significant gull attacks are observed by
monitoring from the air.
Of concern is that aerial monitoring of Banded Stilt chicks may not
expose predator behaviour by gulls because;
a) The Silver Gulls may not be feeding at the same time to coincide
with the monitoring flight.
b) The presence of a low flying aeroplane in the vicinity will
probably disperse any gulls before observers are in range to see what is
happening.
To protect the young Banded Stilts now dispersing across the lake, it is
imperative to expand the operation to target all large gull
concentrations in the area. The reasons are these;
1. During the past week, more than 10,000 additional Silver Gull
nests were discovered in three separate new colonies. These sites are
located less than 15 kilometres from the current position of the
dispersing chicks and more seriously are in their current direct path.
These gulls are not being targeted at this time.
2. Silver Gulls will be hatching soon and compared to the current
situation allowing humane destruction of the gulls, the greater presence
of young will present a major animal welfare problem.
3. When their young emerge, the Silver Gulls at the three closest
concentrations to the stilts will require more available food and their
feeding behaviour will become more aggressive.
4. The Silver Gull concentrations at Lake Eyre are likely to
discourage further breeding attempts in the area this season.
5. At current population levels, Silver Gulls will continue to cause
a major threat to Banded Stilt breeding events in eastern Australia, and
will require expensive ongoing management. It is predictable that the
gulls currently at Lake Eyre will be the core menace and should be
controlled while they are easily identified and accessible.
6. A study carried out in the 1980's by Mr Ian Temby of colour marked
Silver Gulls at Mud Islands in Port Phillip Bay, Victoria proved that
that Silver Gulls regularly move 50 km or more to feed at rubbish dumps
around the city of Melbourne.
The comments from concerned observers expressed to the South Australian
Government authorities about the plight of the Banded Stilt appear to
have provided a positive and constructive environment for correct
decisions to be made. It should be acknowledged that the current
success of this Banded Stilt breeding event is in no small part, due to
the rapid action of NPW. However, the minimalist control strategy
deployed so far is still placing the welfare of the young stilts at
risk. The stakes are too high to consider this occasion just a a
learning event for the future!
Summing up the current picture, the story is mostly good news but, the
fluff balls are not out of the lake yet so to speak! The immediate
threat to Banded Stilts from Silver Gulls has been reduced due to direct
intervention by the Government, but as one observer has pointed out, if
they get this wrong, the Banded Stilt faces annihilation, not
decimation.. It is that serious. A further update will be posted when
more information comes to hand.
After reading the contents of this report, please consider more
encouragement directed at South Australian Government authorities to
expand the Silver Gull control project at Lake Eyre.
Please direct your concern and comments to the following.
Acting Director of National Parks and Wildlife
Mr Lindsay Best
Phone Adelaide (08) 8204 9164
email:
Minister of Environment and Heritage
Phone Adelaide (08) 8226 5855
Fax: (08) 8226 5859
email:
Premier of South Australia
Phone Adelaide (08) 8303 2290
Fax: (08) 8303 2283
email:
Thank you all and regards;
Ian May
PO. Box 666
Enfield Plaza, South Australia. 5085
Tel: Home; (08) 81825858
tel: Mobile; (0409474575)
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