Hope for Carnaby’s Black Cockatoos.
Rick Dawson said it all “The best Landcare night I have ever attended”. It was truly a great night, a champagne event done on a beer budget.
Carnaby Bill
The MC Francis Smit, introduced community mascot Carnaby Bill for photo opportunities, local elder George Walley to welcome guests to country, David Lindsay, Landcare SJ Chair, for a project overview, and guest speaker Rick Dawson from Department of Parks and Wildlife, who all contributed to a well-orchestrated entertaining and informative evening.
Guests included Tony Simpson MLA, representatives of State Government Agencies, including Dept. Parks and Wildlife, WA Museum and State NRM Office, former Landcare SJ staff, regional local government environmental officers, suppliers and customers, community members and volunteers.
George Walley welcomed everyone to country
Unfortunately some people could not make the event, among them Frances Poole, wife of the late John Poole, instrumental in the conception of the project.
Rick introduced himself and gave a history of his endeavours as senior wildlife officer with the Department of Parks and Wildlife and the study site at Coomallo Creek. This site has been monitored by CSIRO and DPaW since 1969.
An important data set of the Carnaby’s Cockatoo breeding habits and nest requirements has been compiled since the outset of monitoring at the site. During this time natural hollows were being lost to deterioration, many requiring repair for re-use. The final blow was a wildfire in late 2009 that destroyed a large section of the study area, leaving only 5 nests in the southern area usable and it was thought this event may mark the end of the area as a breeding site.
Rick Dawson, Dept. of Parks and Wildlife Officer
As a final attempt to save the site Rick thought it might be worth trying some artificial hollows that Landcare SJ were producing.
In 2011, the first Parks and Wildlife order for 30 cockatubes was delivered, of which half were used for successful breeding attempts in the first year. Additional cockatubes were purchased and installed at Coomallo Creek over the following years with varying rates of use and success.
The initial nest boxes provided were between 600mm and 900mmm long, with an internal diameter of between 280mm to 400mm (most 300mm or less).
In 2014 Rick Dawson requested 27 new cockatubes be supplied. The dimensions and quality control aspects of construction were fairly prescriptive. The new nest boxes had to be 1.4m long and 400mm internal diameter. Most of the smaller boxes were removed and replaced with the larger size model.
[perfectpullquote align=”full” cite=”” link=”” color=”” class=”” size=””]That breeding season, every one of the 27 larger cockatubes had a breeding attempt. In 2014 and 2015 the first hollow used in the area was an artificial hollow, and six sets of siblings (twins) were fledged – only the second occasion in 46 years that successful sibling fledging had occurred at the trial site.[/perfectpullquote]
The new cockatubes proved that size does matter, the only issue being the weight, around 50 kg. The increased length was found to deter predators and greater protection from the elements. The increased diameter provided an increased chamber for chicks to grow and develop, which assisted the six sets of siblings that fledged.
Cockatoos were prospecting the smaller dimension cockatubes, but opting for the larger ones when available. The increased depth of mulch from 5cm to 20 cm made for a longer lasting nesting bed, with modifications to the base required to retain mulch within the nestbox longer.
It seemed also that cockatoos were chewing the sacrificial posts to create a bigger chamber in the base of the cockatube creating some doubt about the need for the second sacrificial post. In one of the three remaining hollows of less than 300mm in diameter the post was removed as trial. This hollow had not been used since it was installed in 2011 but without the post it had a successful nesting attempt last year. There is only one sacrificial post now in all hollows at Coomallo and all are 200mm above the nesting floor.
One major concern for the project is the nest temperature. Cockatubes have a higher temperature than natural hollows, heating and cooling much faster as well. Carnaby’s females usually brood the nestling for the first three weeks until the chick has the ability to maintain its own body temperature. However, in these Cockatubes the female was leaving the nestling at a younger age to go off and forage.
Close monitoring showed that the parent was placing her nestling on the sunny side of the nest in the morning gaining some warmth from the nest wall. Rick and his crew were at first concerned that this may not be a good thing but later discovered that with both parents foraging for the nestling it weighed more than an average nestling of that age, which can assist in the successful fledgling.
Tony Simpson, MLA and Landcare SJ Board members; Alan Elliott, Neil Kentish, Dr Dacid Lindsay (Chair), Colleen Rankin and Nancy Scade
In 2015, there was again 101 breeding attempts. Despite artificial hollows only accounting for 40% of total hollows available at Coomallo, 55% of breeding attempts were in Cockatubes. Around this time, Landcare SJ found a new pipe supplier, who could deliver a light weight corrugated pipe with suitable dimensions, and a total weight of 15kg. This new design, and the success at the Coomallo site has led to a further 101 Cockatubes being ordered by Parks and Wildlife. These will be placed in other pressured breeding locations across the Lake Grace district, with a particular focus on supporting Carnaby’s near the township of Borden, and with high hopes for similar results as those achieved at Coomallo Creek.
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photos courtesy of Tony Brown
