Maximising Woodland Bird Diversity in Brigalow Belt Forests (original) (raw)
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Austral Ecology, 2009
The impact of forest management on diurnal bird assemblages and abundance was investigated in contiguous tracts of eucalypt forest in the Brigalow Belt Bioregion, south central Queensland. Sites were located across three levels of livestock grazing intensity and three levels of selective logging intensity within the most extensive habitat type, Corymbia citriodora-dominant forest.We recorded a high rate of incidence and large numbers of the hyper-aggressive noisy miner Manorina melanocephala (Passeriformes: Meliphagidae) at the majority of our survey sites, a phenomenon rarely reported in non-cleared landscapes. As shown by numerous studies in fragmented landscapes, the distribution of this species in our study had a substantial negative effect upon the distribution of small passerine species. Noisy miners exerted the strongest influence upon small passerine abundance, and masked any forest management effects. However, key habitat features important for small passerines were identified, including a relatively high density of large trees and stems in the midstorey. Selective logging appeared to exert a minimal effect upon noisy miner abundance, whereas grazing intensity had a profound, positive influence. Noisy miners were most abundant in intensively grazed forest with minimal midstorey and a low volume of coarse woody debris. Higher road density in the forest landscape also corresponded with increased numbers of noisy miners. Reduction in grazing pressure in Brigalow Belt forests has the potential to benefit small passerine assemblages across large areas through moderating noisy miner abundance. The strong relationship between noisy miners and small passerines suggests that noisy miner abundance could act as an easily measured indicator of forest condition, potentially contributing to monitoring of forest management outcomes.
Emu - Austral Ornithology, 2011
Many of eastern Australia's woodland birds have declined in recent decades. Although historical landscape transformation ultimately underlies these declines, effective conservation action requires knowledge of the relative importance of current threats to woodland birds. Through a literature review and analysis of empirical data from seven woodland regions, we investigated the relative importance of habitat structure, site context and aggressive avian competitors (miners, Manorina spp.) for woodland birds in eastern Australia. The literature review revealed that the factor which most consistently influenced the richness, abundance and assemblage composition of woodland birds was the density or presence of Manorina honeyeaters. A positive effect of site structural complexity was also often reported, but the effects of area, isolation and grazing varied among the reviewed studies. Across the seven empirical datasets, density of Manorina honeyeaters was responsible for the great majority of the independently explained variance in all but one region. We conclude that interspecific competition with Manorina honeyeaters is one of the most important and widespread processes threatening woodland birds in eastern Australia. In regions where this threatening process is prevalent, the greatest conservation gains for woodland birds may therefore be achieved by focussing on reducing habitat suitability for aggressive Manorina honeyeaters.
Austral Ecology, 2007
This study reports on the responses of bird assemblages to woodland clearance, fragmentation and habitat disturbance in central Queensland Australia, a region exposed to very high rates of vegetation clearance over the last two to three decades. Many previous studies of clearing impacts have considered situations where there is a very sharp management contrast between uncleared lands and cleared areas: in this situation, the contrast is more muted, because both cleared lands and uncleared savanna woodlands are exposed to cattle grazing, invasion by the exotic grass Cenchrus ciliaris and similar fire management. Bird species richness (at the scale of a 1-ha quadrat) was least in cleared areas (8.1 species), then regrowth areas (14.6 species), then uncleared woodlands (19.9 species). Richness at this scale was unrelated to woodland fragment size, connectivity or habitat condition; but declined significantly with increasing abundance of miners (interspecifically aggressive colonial honeyeaters). At whole of patch scale, richness increased with fragment size and decreased with abundance of miners. This study demonstrates complex responses of individual bird species to a regional management cocktail of disturbance elements. Of 71 individual bird species modelled for woodland fragment sites, the quadrat-level abundance of 40 species was significantly related to at least one variable representing environmental position (across a rainfall gradient), fragment condition, fragment size and/or connectivity. This study suggests that priorities for conservation management include: cessation of broad-scale clearing; increased protection for regrowth (particularly where this may bolster connectivity and/or size of woodland fragments); control of miners; maintenance of fallen woody debris in woodlands; increase in fire frequency; and reduction in the incidence of grazing and exotic pasture grass.
Landscape Ecology, 2011
We explored the effects of a purported 'reverse keystone species', the Noisy Miner (Manorina melanocephala) using a long-term, large-scale dataset. Specifically, we identify whether this aggressive bird affects the landscape distribution patterns of other avifauna, by displacing them into, or restricting their distribution to, less productive areas, and in so doing, adheres to 'isoleg theory'. We sought to determine the effect of abundance of the Noisy Miner on the abundance of other birds (individual species and groups), and determine whether that effect was consistent with varying site productivity, using a negative binomial distribution with a logarithmic link function, and an offset variable to account for variations in search effort. Relationships between abundance of Noisy Miners and habitat variables were examined using a Poisson distribution with a logarithmic link function scaled for extra-variation (quasi-Poisson regression). We demonstrate that when Noisy Miner abundance is low, many small passerine species are more abundant on high productivity sites. However, as Noisy Miner abundance increases, small passerine abundance decreases, with this decrease most apparent on productive sites. The same patterns were not evident for birds considered 'non-competitors' of the Noisy Miner. We identify that both site productivity and vegetation structure influence the abundance of the Noisy Miner. We reveal that the species increasingly tolerates 'less desirable' habitat attributes with increasing site productivity. The preference of the Noisy Miner for productive areas is likely to have deleterious impacts on the long-term survival and reproductive success of other Australian woodland bird species, many of which have already undergone severe declines. Keywords Reverse keystone species Á Isoleg theory Á Noisy Miner Á Manorina melanocephala Á Temperate woodlands Á Conservation management Á Woodland avifauna Electronic supplementary material The online version of this article (
Bird communities in remnant woodland on the upper North-west Slopes of New South Wales
Australian Zoologist, 2006
Bird counts were conducted in woodland remnants of the upper North-west Slopes of New South Wales, an ornithologically little-documented area, in 1995 and 1997. A total of 120 woodland species, including 11 threatened species, was recorded in the area below 900 m elevation, from a point 100 km NNW of Armidale northwards 50 km to the Dumaresq River, thence 50 km north-west across Slopes woodland to the river at Texas (Queensland). Woodland patches >300 ha supported significantly more species than those <100 ha. Threatened and other declining species occurred mainly in large patches, although some also occurred commonly in small riverine or otherwise fertile patches; foraging guilds of small to mediumsized, ground and above-ground insectivores were under-represented in small remnants. The conservation values of woodland remnants on the upper North-west Slopes are similar to those on the tablelands and inland slopes farther south, and require appropriate management to maintain avian diversity.
Thinning, fire and birds in Boola Boola State Forest, Victoria, Australia
Australian Forestry, 2011
Thinning is a silvicultural technique used extensively throughout Australia's production forests. The longer-term effects of thinning on forest biota are not well understood. This study provides an insight into the effects of thinning on avifauna and vegetation, 5-10 y after a thinning operation. A paired-site experimental design was used to compare bird density and species richness at thinned and unthinned sites in a mixed eucalypt production forest in Gippsland, Victoria. The 2006-2007 fires across Gippsland directly affected eight of twelve sites in this study, providing an opportunity to investigate the immediate effects of wildfire on birds.
The effect of Noisy Miners on small bush birds: an unofficial cull and its outcome
Pacific Conservation Biology, 2008
This paper documents the bird community in a small (~15 ha) patch of remnant woodland New South Wales sheepwheat belt (i) before Noisy Miners Manorina melanocephala were abundant in the patch (1972-79), (ii) after a dense miner colony became established (1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990), (iii) after the miners were removed and, subsequently, (iv) while extensive, dense plantings of native trees became established (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006). Bird species richness in the patch was, respectively, 64, 18, 45 and 83 species in each time period. Totals for small (<120 g) bush birds, mostly insectivorous passerines, were 26, 0, 22 and 46 species in the respective time periods. Although this was an unofficial, unreplicated and uncontrolled activity, the results support those of previous similar studies that indicate that Noisy Miners are a major contributor to the local decline of many woodland birds. The results also affirm the value of a shrub layer to small birds.
The clearance of woodlands and the simultaneous creation of alien environments have been identified as the primary reasons for the decline of many woodland birds in southeastern Australia. This study measured how the size of woodland remnants and habitat structural complexity affected bird composition and distribution in the northern Australian Capital Territory and bordering areas of New South Wales. Within this region only 8% of the original woodlands remain, embedded as patches in a matrix of pasture and suburbia.
Pacific Conservation Biology, 2011
Extensive loss and degradation of native vegetation in the agricultural landscape of inland south-eastern Australia has resulted in significant losses in bird diversity and abundance. Native vegetation continues to be lost through the attrition of paddock trees, which constitute a large component of the remaining vegetation. The planting of native trees and shrubs is being undertaken as a means of halting the loss of biodiversity. However, the effectiveness of revegetation activities is still being assessed. A study in the Wagga Wagga area of New South Wales was undertaken to examine the relative value of remnant vegetation, farm plantings, paddock trees, and pasture for bird diversity. Species richness was highest in remnant vegetation, and was similar in planted vegetation and paddock trees. Relative abundance was similar across these three vegetation types. Species composition differed among all vegetation types, with planted and paddock tree sites having predominantly different ...
Conservation Biology, 1997
Within the southeastern region of Queensland, Australia, native forest cover (bushland) has been greatly reduced and fragmented, and clearing is still occurring. Many of the region's bird species are being increasingly restricted to isolated habitat remnants. However, little is known about the habitat value of these remnants and whether their value is influenced by their degree of connection. We investigated bird use of riparian corridors in pastoral and urban surroundings and riparian linear remnants within an urban context. We compared the avifauna of these remnants with dryland and riparian sites within continuous bushland. We also assessed their use by previously derived response-guilds of birds to bushland clearing. We counted 3567 individuals of 102 bird species. Riparian bushland supported more species and had greater bird abundances than dryland bushland. Corridors and linear remnants supported densities of many bushland-dependent species similar to those in bushland; this varied with species' patterns of large-scale migration and residency. Bushland-dependent winter migrants used both corridors and linear remnants extensively. Bushland-dependent residents were most abundant in continuous bushland and least abundant in linear remnants, possibly reflecting the constraints of central place foraging. Effects of isolation were only evident in resident bushland-dependent species. Local habitat variables were significantly associated with variation in abundance of some types of birds within corridors and linear remnants; however, the differences in bird abundances attributable to spatial characteristics were greater than those attributable to habitat characteristics. The effects of bushland fragmentation and isolation were mediated by the extent to which species are dependent upon bushland and their patterns of large-scale migration or residency. Local habitat, and possibly more importantly altitude, may influence site use by winter migrants and generalist species.