Red-Tailed Black Cockatoo Project

by William B. Emison, Wayne D. Caldow and Joseph M. Foreshaw

Courtesy of World Parrot Trust
E-mail consent obtained from
Michael Pearson and M Reynolds - July 1997

  • Introduction
  • Background
  • Aims
  • Results & Methods
  • Network of Observers
  • Supplementary Nest Hollows
  • Public Awareness & Education
  • Future Direction
  • Further Reading
 

This progress report reprinted courtesy of the World Parrot Trust & The Canadian World Parrot Trust

INTRODUCTION

The Red-tailed Black Cockatoo (Calyptorhynchus banksii) is a well-known and sometimes common bird across much of Northern, Western and Eastern Australia. There is also a small and isolated population of Red-tailed Black Cockatoos (Calyptorhynchus banksii graptogyne) which occurs in South-western Victoria and adjacent parts of the South-east of South Australia (i.e. South-eastern Australia). A recent preliminary study in South-western Victoria indicated that the Red-tailed Black Cockatoo population should be considered endangered for the following reasons:

  • its numbers are low, probably less than 1000 individuals remain
  • the geographical range is small and isolated
  • breeding, which seems to involve only a small proportion of the population (ca. 10% or less) has only been recorded within the northern half of the birds range
  • the diet is specialised
  • nest requirements seem relatively specific
  • and habitats are fragmented and threatened

 

BACKGROUND

Red-tailed Black Cockatoo - Calyptorhynchus banskii. Photo courtesy of Adrian Freeman, Qld Police Service

Research conducted by the Department of Conservation and Natural Resources (DCNR) during 1988-94, found that the loss of Brown Stringybark forests and suitable nesting hollows are the main threats to the Red-tailed Black Cockatoo in South-east Australia. Past clearing of Brown Stringybark forests has reduced this essential habitat and has caused the remaining areas to be broken up and fragmented. Frequent burning, particularly by fires which damage the canopies, may have also had an adverse effect on the food resources of these Cockatoos.

The old, dead, standing River Red Gums on farmland that provide nesting hollows for the Cockatoos are now under serious threat throughout the birds' range. Often these trees are used as a source of firewood. Many others are just pushed over and burnt.

This slow decline in and lack of, available nesting hollows may already be limiting the Cockatoos ability to produce young.

Since the inception of the project, a steering committee has guided the scientific research. The committee is composed of representatives from the Flora and Fauna Branch, Horsham Region, Portland Region, World Parrot Trust and, recently, South Australian National Parks and Wildlife Service. In 1992-94, steering committee meetings were held in Edenhope on 15th December 1992, 28th April 1993, 9th March 1994 and in Mt Gambier on the 15th December 1993. To ensure the long-term survival of the Red-tailed Black Cockatooo in south-eastern Australia, the co-operation and involvement of both the rural community and government departments are required.

Scientists working with the project recommended that a local resident be employed to liaise with the rural community both for enlisting its co-operation in conserving the species and for obtaining more information on the Cockatoo.

The World Parrot Trust (WPT), through the Keith Ewart Charitable Trust, has provided funds to DCNR to employ a person to assist with the project on the Red-tailed Black Cockatoo in SE Australia. This position is part-time and during the 1992-93 and 1993-94 breeding seasons, Wayne Caldow, a farmer in the area where the Cockatoo presently nests, was employed from February to May. The grant from the WPT was for salary; operating costs were provided by DCNR.

AIMS

  • To establish a network of observers in the rural community which will feed back information on distribution, abundance, feeding and nesting of the Red-tailed Black Cockatoo.
  • To gather breeding information from known nest sites.
  • To search for other nesting locations and to obtain historical and current information on breeding sites from members of the rural community.
  • To obtain information on feeding and food preferences.
  • To liaise with landowners to protect nest trees and potential nest trees and to encourage the planting of River Red Gums and Bulokes.
  • To erect a few nest boxes in one of the nesting areas to ascertain if they will be used by the Cockatoos.
  • To determine how fire histories of the blocks of Brown Stringybark influence the distribution of the Red-tailed Black Cockatoo in SE Australia.
  • To investigate genetic differentiation between breeding groups of Red-tailed Black Cockatoos in SE Australia.
  • To obtain a profile of a preferred nest site.
  • To understand the movements, both seasonal and long-term, of the Red-tailed Black Cockatoo in SE Australia.

RESULTS & METHODS

Network of Observers

The network of observers in the rural community (local residents, field naturalist clubs, and schools) which was established in 1991-92 continued to provide Mr Caldow with records (e.g. distribution, nesting, feeding) of the Red-tailed Black Cockatoo.

Breeding Biology

Young Red-tailed Black Cockatoo Chick - Calyptorhynchus banskii. Photo by & courtesy of Garry & Shirley Walsh, Westbrook Qld

Twenty-three nests were found during the 1992-93 breeding season. This total was considerably higher than that for many of the previous four seasons of this study (1988-89, 12 nests, 1989-90, 13 nests, 1990-91, 7 nests, and 1991-92, 3 nests). However, seven of the 1992-93 nests failed, probably because of inclement weather in November and December and we suspect that most of the parents from these failed nests, re-nested in nearby trees. If so, the total number of pairs (16) involved in breeding in 1992-93 was commensurate with those in 1988-89 (12 pairs) and l989-90 (13 pairs).

Because of the nest failures and apparent re-nestings, the fledging of young was very asynchronous in 1992-93. The first fledging was noted on 3rd February (it may have fledged as early as 25th January) and the last indication that a chick was still in the nest was on the 20th May.

Eleven nests were found during the 1993-94 breeding season. The eggs in two of these nests failed to hatch and a young chick disappeared from a third nest sometime between 2nd February and the 10th March. The other eight nests each either appeared to have fledged a young or had a large young present at our last inspection (10th March). Ten of the eleven nesting attempts were in the three known traditional nesting areas in Victoria while one nest was found in South Australia (the first nest found in that State during our study).

In 1993-94, nesting activity was recorded as early as 6th October and the first fledgling was seen on the 4th February.

 

Supplementary Nest Hollows

As our study progressed, we began to suspect that one of the reasons for the low number of nests was because of the loss of suitable nest hollows from traditional Red-tailed Black nesting areas. Many of these losses have resulted from the old dead trees being cut down for firewood, while others have just been pushed over or have fallen from natural decay.

To see if it was possible to assist the nesting of this endangered population, we placed four supplementary nest hollows in dead trees (which did not have suitable natural hollows) in a traditional nesting area after the 1991-92 nesting season. One of these supplementary nest hollows was taken over by a pair of Red-tailed Black Cockatoos in 1992-93 and a young was successfully reared.

After the success of the 1992-93 nesting season, we placed an additional six supplementary hollows in traditional nesting areas. In addition, because we were running out of dead trees in which to place the hollows, we also obtained six disused wooden electricity poles, put them into place in the areas and attached a supplementary nest hollow to the top portion of each one.

So at the start of the 1993-94 nesting season, we had erected 16 supplementary nest hollows (10 supported by dead trees and 6 on SEC poles) in traditional Red-tailed Black Cockatoo nesting areas. At least five of these sixteen hollows were used by nesting Red-tailed Black Cockatoos in 1993-94. At the last examination, (10th March) three of the hollows each had a chick, but two others had failed (an addled egg was present in each of them) . Two of the hollows with chicks were on SEC poles and the other three hollows (one with a chick and the other two with addled eggs) were in the dead trees. Additionally, we have recorded Yellow-tailed Black Cockatoos (Calyptorhynchus funereus), Owls, Long-billed Corellas (Calyptorhynchus tenuirostris) and Maned Ducks using the supplementary hollows. One of the 16 hollows has recently been taken over by feral bees, which will render it unsuitable for use by birds.

Thus, early results indicate that the Red-tailed Black Cockatoo quickly utilises supplementary nest hollows and of the supplementary hollows available, (4 in 1992-93 and 16 in 1993-94) at least 30% have been used by this endangered species.

Public Awareness & Education

During the past year, DCNR continued its awareness campaign on the plight of the Red-tailed Black Cockatoo in SE Australia. The campaign is designed to inform local land owners and public land managers about what they can do to assist with the conservation of this species.

In particular we emphasise the importance of retaining dead and live hollow bearing trees, regenerating areas of River Red Gums and Bulokes, retaining areas of Brown Stringybark forest, reducing the frequency of canopy fires in Brown Stringybark forests and reporting sightings and breeding records of Red-tailed Black Cockatoos.

 

FUTURE DIRECTION

Yellow-tailed Black Cockatoo - Calyptorhynchus funereus. Photograph by Adrian Freeman, Queensland Police Service

Next breeding season, 1994-95, the work will continue to concentrate on the nesting and nesting success of the Red-tailed Black Cockatoo. We are examining the possibility of using volunteers (e.g. Victorian Group of the Royal Australasian Ornithologists Union) to assist us with searches for nests. More measurements to obtain a profile of a preferred nest site will be made. Such a profile will enable us to construct supplementary nests with dimensions suitable for this population of cockatoos. The supplementary nest hollows will be closely monitored and we plan to place more such hollows in suitable areas.

Investigations, (botanical) of the Brown Stringybark trees and the Bulokes (which is also an endangered taxon in Victoria) are required. Such investigations will help us to understand the past and present movements of the Red-tailed Black Cockatoo as well as providing us with information about reasons for success or failure of breeding attempts.

Proposals for a three year study of the movements of the Red-tailed Black Cockatoo in SE Australia are being prepared. This will involve radio-tracking of individuals (probably young of the year) from their nest sites to the feeding and roosting areas. This should provide insight into how far these birds range, how their movements vary from season to season and the importance of their roost sites.

Fire histories of the Brown Stringybark blocks may also be important in helping to understand past and present movements of the cockatoo. In relation to this, and understanding of the effect of fire on the food (Brown Stringybark and Buloke seeds) on this population is required.

The awareness and education campaign and the gathering of information from the network of observers will be continued. The increasing amount of data being collected should eventually allow us to compare monthly or seasonal distributions of this cockatoo. Overlaying distributional maps over vegetation maps and fire history maps could shed further light on the movements of the sub-species and allow us to delineate critical areas of habitat.

Genetic studies focusing on the possibility of inbreeding will continue in 1994-95, DNA analysis of blood samples taken from chicks from the three known breeding areas will be done. Further samples will be collected during the 1994-95 season to augment those collected in 1992-93 and 1993-94.

Procedures for making nest sites secure from illegal egg or chick removal by humans should be drawn up. This will have to be done in collaboration with the law enforcement bodies in both South Australia and Victoria. It is proposed to place microchips in nestlings as a deterrent to illegal poaching and trade of this sub-species.

 

FURTHER READING

  • Emison, W.B. and Joseph, L (1992), "Threats to a population of Red-tailed Black Cockatoos in south-western Victoria." Australian Ranger 25, 33-34.
  • Joseph L (1982), "The Red-tailed Black Cockatoo in south-eastern Australia", Emu 82, 42-45.
  • Joseph, L, Emison, W.B. and Bren W. M. (1991), "Critical assessment of the conservation status of Red-tailed Black Cockatoos in south-eastern Australia with special reference to nesting requirements": Emu 91, 46-50.
  • Schodde, R (1988) "New sub-species of Australian birds." Canberra Bird Notes 13, 119-122.

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(This article was reproduced in theParrot Society of Australia News and on our Internet Site by Courtesy and Permission of the World Parrot Trust)

 

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