Birds of the Great Western Woodlands

by PROFESSOR HARRY RECHER, PROFESSOR WILLIAM DAVIS, DR SANDRA BERRY, PROFESSOR BRENDAN MACKEY, DR ALEXANDER WATSON and DR JAMES WATSON.

Located on the eastern edge of the wheatbelt in south-west Western Australia, the Great Western Woodlands (GWW) is Australia’s largest and most intact landscape of temperate eucalypt woodlands, mallee and shrublands. Encompassing more than 15 million hectares, the GWW extends from Kalgoorlie in the north to Salmon Gums in the south, and from the rabbit-proof fence in the west to the Nullarbor Plain in the east.

Rainbow bee-eater, perched on branch in early morning. Photo: Auscape

WHAT’S SPECIAL ABOUT THE GWW?   

The richness and diversity of the GWW’s plant and animal communities are worthy of world recognition. In terms of biodiversity alone, the GWW ranks in national and global significance with the Great Barrier Reef and the Wet Tropics.   

Not surprisingly, the GWW is also a spectacular place for birdwatching. More than 150 species – including Scarletchested Parrot, Regent Parrot, Malleefowl, and the unique western subspecies of Crested Shrike-tit and Varied Sitella – are found in the region. This tally excludes vagrants and accidentals, waterbirds and waders, and therefore represents an incomplete list given the thousands of shorebirds that congregate on the salt lakes after rain.   

The GWW is probably the last woodland in southern Australia where ecosystems remain relatively intact and there has been no loss of species or populations.   

Uncommon species like Gilbert’s Whistler, Purple-gaped Honeyeater and Regent Parrot have healthy populations here. This is because of the richness and patchiness of the vegetation and the general lack of disturbance by humans and livestock. Uniquely, the core of the GWW is ungrazed by domestic stock, leaving the shrub and ground vegetation intact and the soils loose and friable. In contrast, woodland birds in much of the remainder of southern and eastern Australia are in decline, primarily as a result of agricultural clearing, habitat fragmentation, loss of habitat diversity and degradation of remnant vegetation by domestic stock, feral animals, weeds and changed fire regimes.   

BIRD MOVEMENT   

Although we can describe associations of species and assign them to particular types of habitat, the majority of birds in the GWW are what we call ‘dispersive’. Only a third of the species are resident and sedentary, moving between habitats or locations only when dispersing as juveniles.   

Foremost among the truly dispersive species are the nectar-feeders, or nectarchasers as they might better be described. Aggregations of honeyeaters and Purple-crowned Lorikeet at flowering eucalypts are common. Thousands of individuals are drawn together by the abundance of nectar, with Purplecrowned Lorikeet, Red Wattlebird, and Brown, Spiny-cheeked, White-fronted and Yellow-plumed Honeyeaters being the most abundant. These are joined by smaller numbers of Silvereye, Yellowthroated Miner, and Brown-headed and White-eared Honeyeaters. Predators follow these aggregations and wherever lorikeets and honeyeaters congregate there are Square-tailed Kite, Little and Brown Falcons, and Brown Goshawk and Collared Sparrowhawk soaring low above the canopy or sitting quietly and waiting. Higher above the canopy there are Wedgetailed and Little Eagles, and the occasional Black-breasted Buzzard.   

Nectar-feeders are not the only birds chasing food in the GWW. Large flocks of Striated Pardalotes move about, aggregating wherever lerp is abundant. Trillers, Cuckoo-shrikes, Rufous Whistlers, and Wood-Swallows congregate on outbreaks of caterpillars, grasshoppers and other insects. Parrots and emu seek out fl ushes of young, herbaceous growth. Parrots, quail and doves move in response to rainfall and the availability of seeds, which may be why we’ve seen so few over the past decade of relatively dry conditions in the GWW. Fruit on mistletoes and Native Cherry attracts Mistletoe Birds, whistlers, honeyeaters (especially the Spiny-cheeked Honeyeater), parrots, woodswallows and cuckoo-shrikes among others.   

Whether it is nectar or seed, food can be very abundant. However, the food supply is not permanent. Instead, at any one place, nectar, lerp, seed, young leaves and insects, are abundant for only brief periods (weeks at best). To survive, the birds must continually search for new flowers and for insect outbreaks over vast tracts of woodland.   

Located on the eastern edge of the wheatbelt in south-west Western Australia, the Great Western Woodlands (GWW) is Australia’s largest and most intact landscape of temperate eucalypt woodlands, mallee and shrublands.

These birds that move about in search of temporally abundant food are classed as nomadic. They differ from migrants in that they do not move seasonally between the same locations, nor do they follow the same route when they move. There are migrants in the GWW. Western Warbler, Grey Fantail, Tree Martin, Rainbow Beeeater, cuckoos and Rufous Whistler are migratory, moving seasonally between locations within the GWW to places closer to the coast or inland and north. The Golden Whistler moves seasonally between habitats just as in eastern Australia. In the GWW, however, nomads are much more numerous.   

The movements of nomads are unlikely to be chance wanderings. Just as human nomads are aware of their environment and know where they are most likely to fi nd game or pasture for their herds, nomadic birds probably ‘know’ where and when to find the food they need. Possibly they inherit an ability to respond to weather events, even to rain falling in remote locations. Just as likely, there is a ‘flock memory’ as among human nomads and other herd mammals where the experiences of the oldest individuals guide the entire group. Given that many of these birds may live 10, 15 or 20 years or longer, a flock memory may extend back 50 or more years, more than enough to encompass long-term trends of rainfall and vegetative productivity.   

Because of the large numbers of individuals aggregating in one place to exploit a superabundant food, there is the impression that nomads and other dispersive birds are abundant. This can be misleading. If they were dispersed evenly across the landscape, dispersive species would probably be much less abundant than their more sedentary, non-flocking relatives. Dispersive birds survive in the GWW and appear abundant because the landscape is intact and they form large, conspicuous fl ocks. And therein lies the challenge.   

HOW DO WE PROTECT DISPERSIVE SPECIES?   

A system of static conservation reserves, such as we currently have in Australia, cannot guarantee the resources required by dispersive fauna. Even within the largest reserves, the chance that there will always be some place where food is superabundant is vastly diminished when compared to an unbroken expanse, such as the GWW. As the landscapes surrounding the reserves are modified and degraded, the ability of fauna, including the highly mobile birds, to find the resources on which they depend by moving between reserves and less disturbed areas is compromised. The effect of small size and isolation of reserves is intensifi ed by drought and wildfi re, not to mention the changes being brought on by accelerated global warming.   

The failure of a static reserve system to cater for dispersive fauna does not mean our conservation reserves have no value. They have considerable value and form the core of the WildCountry approach to conservation management in Australia.   

WildCountry inverts the conservation paradigm. In place of a few reserves embedded in a landscape of alienated lands, we envision nodes of development and human enterprise embedded in a matrix of lands managed for conservation. This is our goal for the GWW: an intact landscape, linked across the south-west by unbroken bands of native vegetation extending from the Indian Ocean and Great Southern Bight, into the mulga woodlands and desert of the interior, and across the Nullabor, managed for conservation. Human enterprise is retained and development can occur, but in our vision for the GWW honeyeaters will always be able to chase nectar and be pursued in turn by swift falcons.   

This is an edited version of an article that was first published in the Birds Australia magazine Wingspan, Vol. 17, December 2007

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