Psittacine Circoviral (beak and feather) Disease

1. Name and description of the key threatening process

The nomination for listing 'Psittacine Circoviral (beak and feather) Disease' as a Key Threatening Process was originally submitted under the Endangered Species Protection Act 1992 (ESP Act).

Psittacine Circoviral (beak and feather) Disease is a disease affecting parrots and their allies (psittacines). It is often fatal to birds that contract it, and most species do not respond to treatment.

The epizootiology (the study of epidemic disease in animals) is not fully understood. The PCD virus is one of the smallest and most resistant viruses capable of causing disease, and would remain viable for many years in nest boxes and hollows. The virus can remain present in the environment for many years and may result in long-term contamination of nesting sites.

Acute and chronic forms of PCD are recognised. In the acute form diarrhoea and feather abnormalities are symptoms, and death may occur suddenly within one to two weeks of developing clinical signs. The chronic form results in feather, beak and skin abnormalities, with most birds eventually dying. Complete or partial recovery from acute PCD has been recorded in some species (budgerigars, rainbow lorikeet, lovebird, king parrot and eclectus parrot), perhaps related to antibody in the blood. The majority of psittacine species with chronic PCD do not have antibody, do not recover and do not respond to treatment.

The disease is believed to have evolved with wild psittacines and is widespread in wild psittacines, including many common Australian species (eg. Sulphur-crested Cockatoo, Galah). The nomination and experts agree that in circumstances where bird populations have been dramatically reduced, such as in endangered species, the disease may have the potential to cause catastrophic losses.

In addition, the nominator believes that when captive breeding is practiced as an option to increase numbers of threatened bird species, PCD virus will spread much more readily. Captive breeding for re-introduction is underway for the Orange-bellied Parrot and Norfolk Island Green Parrot, but is not currently occurring for the other listed endangered psittacine species. However, captive management, investigation of appropriate husbandry techniques, and establishment of a captive population have been recommended or are underway for: Carnaby's Black-Cockatoo Calyptorhynchus latirostris, Night Parrot Pezoporus occidentalis, Western Ground Parrot Pezoporus wallicus flaviventris and Coxen's Fig Parrot Cyclopsitta diophthalma coxeni.

There is no evidence that the disease is a threat to the survival of psittacine species which are not endangered.

TSSC therefore recommend that the threatening process be re-defined as: 'Psittacine Circoviral (beak and feather) Disease affecting endangered psittacine species'.

2. How judged by TSSC in relation to the Environment Protection and Biodiversity Conservation Act 1999 criteria

In its original assessment, the nominated process was found (by the Endangered Species Scientific Sub-committee, ESSS):

1. to meet the ESP Act criterion for 'adversely affecting two or more listed species';
2. to meet ESP Act criterion 'that it could cause native species that are not endangered to become endangered'; and
3. To meet the ESP Act criterion that a nationally co-ordinated threat abatement plan is a feasible, effective and efficient way to abate this process.

Subsequent to this advice the process could not legally be added to the list of key threatening processes under the ESP Act, since it occurs both in and outside Commonwealth areas. This restriction is no longer applicable under the EPBC Act.

A. Could the threatening process cause a native species or an ecological community to become eligible for listing as Extinct, Extinct in the Wild, Critically Endangered, Endangered or Vulnerable?

Psittacine Circovirus Disease (PCD) has been recorded in over 38 species of captive and wild psittacine birds (parrots and their allies) in Australia. Due to the nature of the virus all Australian psittacine species are susceptible to infection. The disease is likely to have occurred in psittacines for a long time, and does not necessarily represent a major threat to a species unless there are few populations or limited numbers of birds which are vulnerable to catastrophic events, such as a PCD epidemic.

Conclusion: Based on the evidence provided and summarised above TSSC considers that the threatening process is not eligible under this criterion.

B. Could the threatening process cause a native species or an ecological community to become eligible to be listed in another category representing a higher degree of endangerment?

PCD is a threat to the survival and abundance of two endangered species: the Orange-bellied Parrot Neophema chrysogaster, and the Norfolk Island Green Parrot Cyanorhamphus novaezelandiae cookii.

The Orange-bellied Parrot captive breeding program (a significant part of the Recovery Plan) initially encountered major problems due to PCD. These problems included high juvenile mortality and delay of the release of captive bred birds until the disease was recorded in the wild. In the wild there is one sub-population of Orange-bellied Parrots, containing approximately 180 breeding birds. Recovery actions to improve the size of the wild population include monitoring and managing PCD in the captive population, and development of a PCD vaccine.

On Norfolk Island PCD has caused the death of a small number of Norfolk Island Green Parrots, and it is now thought to be widespread in the wild population. PCD related requirements for recovery of the species include captive breeding, reintroduction, and investigating immunisation of wild parrots. The entire subspecies is represented by two sub-populations, one wild and one captive, and both are vulnerable to a single epidemic.

Conclusion: Based on the evidence provided and summarised above TSSC considers that the threatening process is eligible under this criterion as it could cause two native species (Orange-bellied Parrot and Norfolk Island Green Parrot) to become eligible to be listed in another category representing a higher degree of endangerment (Orange-bellied Parrot - Critically Endangered and Norfolk Island Green Parrot - Critically Endangered).

C. Does the threatening process adversely affect 2 or more listed threatened species (other than conservation dependent species) or 2 or more listed threatened ecological communities?

PCD adversely affects at least two endangered species (Orange-bellied Parrot and Norfolk Island Green Parrot). In addition, the following listed endangered species are likely to be within the host range for PCD, and have characteristics which may increase their vulnerability to catastrophic epidemics of the disease: a small number of breeding birds; the number of breeding birds decreasing; and/or few sub-populations. PCD has been recorded in three of these species (marked *).

Species	No. breeding birds	Trend	No. sub-popns
Calyptorhynchus banksii graptogyne South-eastern Red-tailed Black-Cockatoo	560	decreasing	1
Calyptorhynchus lathami halmaturinus Glossy Black Cockatoo (Kangaroo Is. Subspp)	140	increasing	1
*Calyptorhynchus latirostris Carnaby's Black-Cockatoo	60000	decreasing	4
*Lathamus discolor Swift Parrot	2000	decreasing	1
Pezoporus occidentalis Night Parrot	50	fluctuating	5
Pezoporus wallicus flaviventris Western Ground Parrot	400	decreasing	3
*Psephotus chrysopterygius Golden-shouldered Parrot	2000	decreasing	2
Cyclopsitta diophthalma coxeni Coxen's Fig-parrot	100	decreasing	4

(data from Action Plan for Australian Birds, Garnett and Crowley 2000)

Because the full host range of the disease is not clear, it is also possible that other groups of birds may prove susceptible, in addition to all other Australian psittacines.

Conclusion: Based on the evidence provided and summarised above TSSC considers that the threatening process is likely to adversely affect two or more listed threatened species (Orange-bellied Parrot, Norfolk Island Green Parrot, 8 other endangered psittacine species) and is therefore eligible under this criterion.

Conclusion - The threatening process meets s188(4)(b) and s188(4)(c) of the EPBC Act. PCD may cause a number of species to become listed. It is considered a threat to two endangered species (Orange-bellied Parrot and Norfolk Island Green Parrot) to the extent that without preventative action these species may become Critically Endangered. The disease also adversely affects a number of other listed species.

3. Threat Abatement Plan

In their original assessment of the nomination ESSS advised that 'the preparation and implementation of a nationally co-ordinated threat abatement plan is a feasible, effective and efficient way to abate the process'.

Relevant points are:

• The disease has a broad host range, possibly including pigeons in addition to probably all native psittacine species, but the details of its epizootiology in most species are unclear.
• Treatment of affected birds is not an option at present, and abatement depends on advances in control and prevention of the disease with effective vaccines and a strategy to deliver them.
• A vaccine has been developed which induces immunity in vaccinated birds - this is a feasible method of abatement for captive bred birds and in regularly captured small populations of wild birds. Two targets for this treatment would be the Orange-bellied Parrot and the Norfolk Island Green Parrot.
• Reservations have been expressed concerning the value of any vaccine for wild flocks, and there is a need for studies of the effectiveness of any vaccine for treatment of different psittacine species.

A Threat Abatement Plan could efficiently address two aspects of recovery of threatened bird species: the elimination of the disease from captive breeding programs (and hence birds released into the wild); and reduction of the incidence in wild populations.

Incidence of the disease in wild populations could be reduced by ensuring that a National vaccination program was routinely carried out as part of Psittacine population monitoring and management activities (in particular for threatened species). This would effectively minimise the risk of spread of the disease to other individuals in species where the disease already occurs (eg. Orange-bellied Parrot, Swift Parrot) and to other threatened species which may be susceptible.

Conclusion - A Threat Abatement Plan is considered to be a feasible, effective and efficient way to abate PCD effects on endangered species. The plan would target small populations of endangered parrots, particularly Norfolk Island Green Parrot and Orange-bellied Parrot, where close monitoring of small wild populations and captive breeding are critical to recovery. A threat abatement plan would be less feasible for large wild flocks. Given that the threat of PCD to these species is also less clear, this reinforces the suggestion to re-define the threat as 'Psittacine Circoviral (beak and feather) Disease affecting endangered psittacine species'.

4. Recommendations

1. The TSSC recommends that the list referred to in section 183 of the EPBC Act be amended by including in the list as a key threatening process: 'Psittacine Circoviral (beak and feather) Disease affecting endangered species'.
2. A Threat Abatement Plan is considered to be a feasible, effective and efficient way to abate the threatening process.