Likely Climate Change Impacts on Birds in South-East Queensland

An isolated population of the Eastern Bristlebird occurred in the Conondale Range in the Sunshine Coast hinterland - the northern limit of its distribution. Discovered as recently as the 1980s, the population appears now likely to be extinct as there have been no confirmed records for several years - see here for more.

Eastern Bristlebird

The Spotted Quail-Thrush was formerly seen with regularity at sites such as Widgee, Eudlo, Wild Horse Mountain and Brooyar State Forest in the Sunshine Coast hinterland. The species is now absent from these sites, with no confirmed records in recent years, and appears to be extinct in the Sunshine Coast region. It has declined elsewhere in South-East Queensland but small populations persist in some areas, even in the outer suburbs of Brisbane.

Spotted Quail-Thrush

In the Sunshine Coast region, the Crimson Rosella was formerly common in rainforest and wet sclerophyll forest at all altitudes. It is now found only in the highest parts of the Conondale and Blackall ranges, and in much smaller numbers than previously. For instance, at Booloumba Creek and Charlie Moreland Park in the 1970s, Crimson Rosellas were common, but they are scarce at those sites today. The species remains common in the higher, cooler parts of the McPherson and Great Dividing Ranges.

Crimson Rosella

A similar story applies to the Satin Bowerbird. The population of this species in the Sunshine Coast region is concentrated these days in the highest parts of the Conondale and Blackall Ranges. The bowerbird was formerly a common winter visitor to lowland sites where it has not been seen for many years or is now a vagrant. In places such as Little Yabba and Booloumba creeks, where it was once numerous, it is now uncommon. Again, the species remains common at higher altitudes in mountains to the south.

Red-browed Treecreeper

The Red-browed Treecreeper, though always uncommon, is now decidedly rare in the region. It continues to be found occasionally in the wet sclerophyll forests of the Blackall and Conondale ranges - the northern end of its distribution - but the treecreeper is absent from many of its former haunts. I have seen just a single bird in the Blackall Range during multiple visits over the 7 years that I have been living in the region. I have searched without success for them at sites in the Conondale Range where they were once regular.

Olive Whistler

The Olive Whistler just creeps across the Queensland border, occurring in high altitude Nothofagus forest in the McPherson Range. The species was always scarce in Queensland but the bird could usually be found in the 1970s without too much effort at sites such as Mt Bithongabel. However, records have declined over the past 20-30 years and it is uncertain if the species has been definitively recorded in Queensland in recent years; it may be extinct in the state.

What these species have in common is that they are close to or at the northern end of their distribution in south-eastern Australia, although the rosella, bowerbird and quail-thrush have isolated populations in north Queensland. Observers have noted steep, parallel declines in populations of several formerly common mammal species in the region such as Boebuck, Red-legged Pademelon and Greater Glider.

Warmer temperatures and drier conditions may be related to the decline in populations of these mammals and birds. In the case of the bristlebird, inappropriate vegetation management by state authorities and predation by feral cats and foxes are likely to have been additional factors in its demise.

Fairy Gerygone

Conversely, numbers of some essentially tropical species are expanding in the Sunshine Coast region. The Fairy Gerygone was not formerly known south of Gin Gin but it is now regular and quite common in places in vine scrub in coastal dunes and in the hinterland.

The Dusky Honeyeater, another tropical species, is also more widespread today around the Sunshine Coast than it was in the 1970s. While it was formerly restricted essentially to lowland vine scrubs in and about the Conondale Range, the honeyeater is today seen in a variety of habitats across the region. It is a regular visitor to my garden at Ninderry.

Dusky Honeyeater

Similarly, numbers of other essentially tropical birds such as Pale-vented Bush-hen and White-eared Monarch appear to have increased. Both of these species were thought to be summer visitors to South-East Queensland but they are now believed to be resident.

The phenomenon is also apparent in mammals. In the 1970s, flying-fox populations in south-east Queensland were overwhelmingly comprised of Grey-headed Flying-Fox, with the tropical Black Flying-Fox a scarce visitor. These days, Grey-headed Flying-Foxes are greatly outnumbered by Black Flying-Foxes, while the distribution of the Grey-headed Flying-Fox has headed southwards.

Black Flying-Fox

 The influence of climate change on bird populations overseas is now widely acknowledged. There is no conclusive evidence that the declines and increases underway in South-East Queensland are due to climate change, but in most cases there have been no other factors in evidence - such as reduced habitat or increased predation from feral predators. Moreover, the trend reflects that in many places overseas. The concern is that some populations, such as those inhabiting the northern-most sites known for the Eastern Bristlebird and Olive Whistler, are disappearing over an alarmingly short span of time.