Birds under threat in our South West

Katherine Veness's blog | Created 9 years ago

The southwest region of Western Australia is a world biodiversity hotspot. This means it is an area of significant biodiversity considered to be under threat from human activity. To illustrate this point, consider that there are over 350 species of bird native to the South West. Of these, 14 are endemic. All these species have been affected in some way by European colonisation.

History of the South West

During the 1920s and 1930s alone, European settlers cleared 40, 000 sq. km of land in the South West. Since this time the area has continued to have a history of urban growth. This activity has facilitated huge changes in biodiversity. These include the introduction of non-native plants and feral animals.  Land clearing has also affected the quality of soil, which has significant flow-on effects to native fauna. 

Invaders

While European colonisation has caused the loss of many native bird species, settlers also introduced many species. For example, the Wheatbelt area has lost nine species of bird, but has gained five. The Swan Coastal Plain has lost seven species of bird, and gained six.

Settlers introduced non-native bird species to help them feel more at home in this isolated corner of the vast Australian continent. These new species meant increased competition for resources with native species. Not all species, such as the turtledove and partridge, survived in the unfamiliar habitat. However some, such as the Laughing Kookaburra, thrived. The Kookaburra was introduced in 1897 to control snake numbers. Although successful, it also preyed upon other native species, threatening their numbers. 

Other species invaded on their own, such as the Galah and Australian White Ibis. These birds are now a common sight throughout the South West. 

Native Inhabitants 

Some species of native bird have benefited from the agricultural evolution of the South West. The Australian Magpie and Magpie-lark have become more widespread as the countryside has opened up.

Other native species, such as the Dusky Woodswallow, have been restricted in their range, as preferred habitats were destroyed.  Out of necessity, this swallow has invaded Jarrah forest habitats, which have themselves dwindled.

Some native species have not survived European settlement at all.

Some species of bird suffered too much pressure from the threats introduced by European colonisation, and have become extinct in the South West region, if not the world. The last recorded sighting of the Rufous Bristlebird, for example, was in 1908. Researchers haven't recorded Lewin’s Rail in the South West since 1932. 

What about Perth? Wungong: a case study

The general outlook for bird species trying to survive in the greater Perth region is poor. Many species have disappeared, have been forced out of their natural habitat, and/or face competition from feral species.

Perth is famed for its abundance of bushland reserves and parks, however climate change is a major threat to ecosystem equilibrium, and Dieback affects huge areas of bushland. Other threats include land development, urban sprawl, and continued invasion of non-native species.

Some bushland areas, however, offer hope to the future of South West native birds.

The Wungong Dam Catchment is a 132 km² area of dominant Jarrah-Marri woodland to the south-east of Armadale. In Birds of the Wungong Dam Catchment, published in 2008, all species of bird observed in the catchment were recorded over many years, totalling 124 species. 12 of these species are non-native, including one-off sightings of the Common Peafowl, the Domestic Goose and Pigeon.

Despite these feral species, the Wungong Dam Catchment is considered to have a ‘rich assemblage’ of native birds (Johnstone and Kirkby 35), especially when compared to estimates of bird species abundance in the greater Perth region. 

Browse our photo gallery of Bungendore Park, part of the Wungong Dam Catchment. 

Black Cockatoos

The Wungong Dam Catchment is important for another reason. It contains the largest known breeding population of Forest Red-tailed Black Cockatoo, Calyptorhynchus banksii naso, in the South West (Johnstone and Kirkby 35).

C. b. naso is endemic to South West Western Australia. This impressive species is listed as Vulnerable due to the impact of habitat destruction and fragmentation, logging, competition for nest hollows, and fire (Johnstone et al. 154). As such, it has disappeared from approximately 30% of its former range (Johnstone et al. 154). 

Several actions have been proposed in order to help re-establish C. b. naso population numbers and distribution.  These include:

• Placement of artificial hollows in appropriate nesting sites,
• Population control of nest competitors such as the European Honey Bee, Galah, and feral Corella, and
• Policy changes to protect Forest Red-tailed Black Cockatoo habitat.

C. b. naso isn’t the only endangered Black Cockatoo with important breeding sites at Wungong. A small population of Carnaby’s Cockatoo (Calyptorhynchus latirostris) also uses the area for breeding, and it is an important roosting site for Baudin’s Cockatoo (Calyptorhynchus baudinii). 

Other rare and endangered bird populations also call Wungong home, including the Rufous Treecreeper, Red-winged Fairy Wren, Grey Currawong, and many more (Johnstone and Kirkby 35).

Birds of the future

Despite the threats facing our native South West birds, positive changes are afoot. Public awareness of environmental problems is increasing. As such, joint management programs and conservation initiatives are more common.

A prime example is Cockatoo Care, a joint Western Australian Museum and Water Corporation initiative. The program was established to learn more about our Black Cockatoos and to help increase dwindling population sizes. The program has been running since 2001 and has had a measurable impact on Black Cockatoo conservation, including the status of the Forest Red-tailed Black Cockatoo and Baudin’s Cockatoo being upgraded to endangered.  

Further Information and References

This article was partly based on a lecture given by Claire Stevenson. Watch it to find out more, including the tale of the Noisy Scrub-bird. 

Papers and advice were provided by Western Australian Museum Ornithology Curator Ron Johnstone.

R.E. Johnstone, T. Kirkby and K. Sarti, 2013. The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. I. Characteristics of nest trees and nest hollows. Pacific Conservation Biology Vol. 19: 121-142. Surrey Beatty & Sons, Sydney.

R.E. Johnstone and T. Kirkby, 2008. Birds of the Wungong Dam Catchment. Western Australian Museum. Pp. 1-54.