The reasons for the population decline of the Orange-bellied Parrot (OBP) are not clear.
Past and ongoing habitat loss and degradation, particularly in the
migration range in northwest Tasmania and the Bass Strait islands, and
the wintering range in southeastern mainland Australia is believed to be
one of the greatest threats to OBPs
known and potential threats to the OBP include:
- loss of genetic
diversity and inbreeding
- stochastic environmental events (e.g.
- climate change
- predators (e.g. Foxes and Cats) and competitors (e.g. Goldfinch and Starlings)
- barriers to migration and
- hybridisation with Blue-winged Parrots.
Orange-bellied Parrot in its breeding range at Melaleuca. Photo: Col Rowe
Habitat degradation and fragmentation
is likely that fragmentation and loss of the wintering habitat over the
last 100 years could be a significant cause for the OBP population decline.
OBP habitat has been degraded and lost
throughout its range, but much of this impact has occurred within the
non-breeding range (i.e. migratory corridors and wintering areas)
including: drainage of wetlands for grazing; alteration and destruction
of saltmarsh for industrial and urban development; stock grazing of
native vegetation; vegetation clearance for agricultural purposes; and
disturbance through recreational activities (e.g. off-road vehicles). It
also appears that the breeding range of the species has contracted. In
recent years, few OBPs have been found outside the Melaleuca area where
all known breeding now occurs and the causes of this contraction are not
The decline in female breeding participation over recent
years was possibly influenced by reduced female condition. While the
causal links are not clear, the extended drought between 1997 and 2010
may have reduced the quality and availability of food resources at key
sites on the mainland prior the breeding season. This may have been
exacerbated by the lack of ecological burns in the Melaleuca area, which
further reduced the quality, and availability of some food sources.
Interactions with other species may have also influenced the contraction
of the breeding range.
Although there is a lack of
clear evidence that predation of OBPs by foxes
and cats is a serious threat, anecdotal observations on the mainland
suggest there is the potential. A fox has been observed stalking OBPs
(L. Robinson pers. comm. in Orange-bellied Parrot Recovery Team 2014) and evidence of cat predation of a Blue-winged Parrot was observed at a site where OBPs were also seen (J. Starks
pers. comm.in Orange-bellied Parrot Recovery Team 2014). Intuitively, the presence and high abundance of these
introduced predators at OBP sites must increase the level of mortality
and thus limit recovery potential.
There is also some evidence that sugar gliders may have killed three, but potentially six OBPs during
translocations of the birds to Birchs Inlet between 1999 and 2005
(Holdsworth 2006). Sugar Gliders (Petaurus breviceps) have not been recorded at Melaleuca.
Nest box competitiors and predators at Melaleuca recorded by a Scoutguard motion sensor camera. Photo: DPIPWE
The introduced European Rabbit
(Oryctolagus cuniculus) grazes on saltmarsh and beach-dune vegetation
and on weed species, though the impact this has on food availability for
OBPs has not been assessed. In the breeding
grounds, Common Starlings (Sturnus vulgaris) have aggressively prevented
OBPs from entering known nest-hollows (Higgins 1999).
(Apis mellifera) are also known to invade and occupy tree hollows and
nest boxes to the exclusion of OBPs. Sugar Gliders also compete for nest
sites at Birchs Inlet.
Weed invasion of native vegetation has
the potential to degrade potentially suitable OBP foraging habitat. The
loss of large areas of saltmarsh to pasture has resulted in the spread
of agricultural weeds, in places seriously degrading remnant saltmarsh
communities (McMahon et al 1994). The introduced salt-tolerant Rice
Grass (Spartina anglica) invades and out-competes saltmarsh vegetation
such as Beaded Glasswort, potentially reducing available foraging
habitat. In Tasmania, introduced Marram Grass (Ammophila arenaria)
and Sea Spurge (Euphorbia paralias) are the subject of intensive
eradication efforts within the Tasmanian Wilderness World Heritage Area.
Both species are vigorous colonisers and out compete a range of native
OBP food plants. The spread of sea spurge is also exacerbated by dune
erosion caused by cattle grazing along coastal areas of the northwest
and Bass Strait islands (i.e. areas used during migration).
Beak and Feather Disease
Psittacine Beak and Feather Disease (PBFD)
virus causes beak and feather abnormalities in parrots. In 2001 PBFD was
listed as a key threat to at least 25 threatened Australian species or
subspecies under the Environment Protection and Biodiversity
Conservation Act 1999 (DEH 2005). This disease is also recognised as a
threat in the National Recovery Plan for OBPs (OBPRT 2014).
Infected parrots have
potential to either succumb to disease, or recover and develop
antibodies. There is also potential for clinically normal birds to shed
virus periodically through their life. The virus is known to be present
in many widespread and common parrot species, including sulphur-crested
cockatoos, rainbow lorikeets and crimson rosellas, species that may
have contact with the OBPs either at the single-OBP Melaleuca breeding
site in the Tasmanian Wilderness World Heritage Area or their mainland
wintering grounds (DEH 2005, Peters et al., 2014, Eastwood et al.,
PBFD virus has also recently been found in green rosellas which
co-occur with OBPs at Melaleuca. The existence of reservoirs
for PBFD in wild parrots throughout the range of OBPs is therefore
highly likely. Infected chicks typically become symptomatic as they
undergo feather development, yet adults rarely become clinically
affected (DEH 2005).
Cause of the 2014-15 PBFD virus outbreak
Over the past 30 years, PBFD has been confirmed at multiple times in both the captive and wild OBP population.
of the virus in the 2014-15 outbreak indicated that it was a likely to
be a result of disease spillover/transmission from another parrot
species in the wild, rather than from the captive bred release birds.
Since the outbreak, in June 2015 an expert “Veterinary Technical
Reference Group” (VTRG, a Working Group of the Recovery Team) was formed
to provide timely expert advice in relation to OBP health, disease and
There has been preliminary work on the development of a
PFBD virus vaccine. However, as it is unlikely that a vaccine will be
available for some time, important management activities such as the
release of captive-bred OBPs into the wild population will need to be
considered without the aid of vaccination.
M.C. 2006. Reproductive success and demography of the orange-bellied
parrot Neophema chrysogaster. M Sc thesis, University of Tasmania,
P.J. (ed.) (1999). Handbook of Australian, New Zealand and Antarctic
Birds. Volume Four - parrots to dollarbird. Melbourne: Oxford University
McMahon, A.R.G., Race, G.J. and Carr, G.W. 1994. Vegetation
survey and remote sensing of Victorian saltmarshes in relation to
orange-bellied parrot Neophema chrysogaster
habitat. Ecology Australia
Holdsworth, M.C. and Rounsevell, D.E. 1994. Captive breeding and
release as a means of increasing the orange-bellied parrot population in
the wild. Pp. 135-141 in Serena, M. (Ed.) 1995. Reintroduction Biology
of Australian and New Zealand Fauna. Surrey Beatty, Chipping Norton.
(2005). Threat Abatement Plan for Beak and Feather Disease affecting
endangered psittacine species. Department of the Environment and
Heritage, Canberra, ACT.
Eastwood, J.R., Berg M.L, Spolding, B.,
Buchanan K.L., Bennett, A., and K. Walder (2015). Prevalence of beak and
feather disease virus in wild Platycercus elegans: comparison of three
tissue types using a probe-based real-time qPCR test. Australian Journal
of Zoology 63 pp. 1–8
Orange-bellied Parrot Recovery Team (2014).
(Draft) National Recovery Plan for the Orange-bellied Parrot. Neophema
chrysogaster. Department of Environment and Primary Industries, East
Peters, A., Patterson, E.I., Baker, B.G., Holdsworth, M.,
Sarker, S., Ghorashi, S.A. and S.R.Raidal (2014) Evidence of Psittacine
beak and feather disease virus spillover into wild critically endangered
orange-bellied parrots (Neophema chrysogaster). Journal of Wildlife
Diseases 50: DOI: 10.7589/2013-05-121.