Relative influence of habitat modification and interspecific competition on woodland bird assemblages in eastern Australia (original) (raw)
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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 (
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.
Royal Society Open Science, 2020
Birds are declining in agricultural landscapes around the world. The causes of these declines can be better understood by analysing change in groups of species that share life-history traits. We investigated how land-use change has affected birds of the Tasmanian Midlands, one of Australia's oldest agricultural landscapes and a focus of habitat restoration. We surveyed birds at 72 sites, some of which were previously surveyed in 1996–1998, and tested relationships of current patterns of abundance and community composition to landscape and patch-level environmental characteristics. Fourth-corner modelling showed strong negative responses of aerial foragers and exotics to increasing woodland cover; arboreal foragers were positively associated with projective foliage cover; and small-bodied species were reduced by the presence of a hyperaggressive species of native honeyeater, the noisy miner (Manorina melanocephala). Analysis of change suggests increases in large-bodied granivorous or carnivorous birds and declines in some arboreal foragers and nectarivores. Changes in species richness were best explained by changes in noisy miner abundance and levels of surrounding woodland cover. We encourage restoration practitioners to trial novel planting configurations that may confer resistance to invasion by noisy miners, and a continued long-term monitoring effort to reveal the effects of future land-use change on Tasmanian birds.
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.
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.
Approximately 90% of the original woodlands of the Mount Lofty Ranges of South Australia has been cleared, modified or fragmented, most severely in the last 60 years, and affecting the avifauna dependent on native vegetation. This study identifies which woodland-dependent species are still declining in two different habitats, Pink Gum–Blue Gum woodland and Stringybark woodland. We analyse the Mount Lofty Ranges Woodland Bird Long-Term Monitoring Dataset for 1999–2007, to look for changes in abundance of 59 species.Weuse logistic regression of prevalence on lists in a Bayesian framework, and List Length Analysis to control for variation in detectability. Compared with Reporting Rate Analysis, a more traditional approach, List Length Analysis provides tighter confidence intervals by accounting for changing detectability. Several common species were declining significantly. Increasers were generally large-bodied generalists. Many birds have already disappeared from this modified and naturally isolated woodland island, and our results suggest that more specialist insectivores are likely to follow. The Mount Lofty Ranges can be regarded as a ‘canary landscape’ for temperate woodlands elsewhere in Australia – without immediate action their bird communities are likely to follow the trajectory of the Mount Lofty Ranges avifauna. Alternatively, with extensive habitat restoration and management, we could avoid paying the extinction debt.
A Four-Year Study of a Bird Community in a Woodland Remnant Near Moyston, Western Victoria
Corella, 2003
at a woodland remnant near Moyston in western Victoria. The migratory status of each species was assessed. Changes in abundance seasonally and over a longer period are reported. The results indicate that this remnant .is used by about thirty species of resident birds as well as supporting various migrants and partial migrants. The study site was occasionally visited by large numbers of several nectarivorous species. Two resident species (Hooded Robin Melanodryas cucullata and Buff-rumped Thornbill Acanthiza reguloides) disappeared during the survey, and another (Speckled Warbler Chthonico/a sagittatus) has since disappeared from the remnant. These species are all ground nesters and/or ground feeders. Such species are of conservation concern across the temperate woodlands of southeastern Australia, as they also have declined elsewhere in these habitats in recent decades. The White-browed Scrubwren Sericornis frontalis was a resident by the survey's completion, having been recorded only sporadically earlier in the study. The results give insight into the movements of birds at this site and presumably other woodland remnants in the area. The loss of resident species witnessed here is a tangible example of a loss of species occurring at a larger scale in temperate woodlands in Australia. S. J. Kennedy: Study of a bird community in a woodland remnant near Moyston, Western Victoria Corella 27(2) The area has a temperate climate with average monthly maximum temperatures ranging from 27.7°C in January to 11. I °C in July, and average monthly minimum temperatures ranging from I 2.6°C in February to l.7°C in June and July (temperature data are for Ararat, 16 km to the cast). Moyston receives an average of 573 millimetres of rain per year (LCC I 980), with most rain falling in winter and spring. Censusing A single, strip transect (approximately 1.5 km in length and I 00 m in width) was used to estimate bird species richness and abundance. The transect route extensively sampled all habitats of the remnant, and was completed in approximately four hours. Censuses commenced at sunrise or soon after on overcast mornings. Every bird sighted during the census was recorded and counted. Care was taken Lo avoid double counting. Birds heard calling from within the remnant were recorded when they were first heard, and if they were not ullimately sighted during the survey they were counted as 'one'. Birds using the aerial space over the study site for hunting (e.g. raptors) or feeding (e.g. martins or swallows) are included in the results. Data collected on other birds flying over the transect are not included in this paper. The census was made on the second or third weekend of each month between September 1989 and February I 994. There were five censuses in the spring and summer months and four in the autumn and winter months. Counts were averaged across the years. Classifirn1io11 of migrawry stmus At the completion of data collection the seasonal variation in abundance of each species was assessed and each species was classed as a resident, migrant, partial migrant, or visitor. The definitions of migratory status have been adapted from Er and Tidemann (1996).
Bird communities in remnant woodland on the New England Tablelands, New South Wales
2006
We provide a geographic and landscape context for ongoing studies on bird communities in eucalypt woodland remnants on the New England Tablelands, New South Wales. We draw together several surveys that have not been published in the scientific literature, and integrate them with previously published material. A total of 142 woodland bird species, including 12 threatened species, was recorded in remnant woodland in the area above 900 m elevation from 50 km SSE to 100 km NNW of Armidale. There was a positive relationship between remnant size and bird species richness. Woodland reserves >300 ha supported significantly more species than remnants <100 ha on private land. Intensively surveyed reserves also had more species than remnants surveyed more casually. Threatened and other declining species occurred mainly in medium-sized (100-300 ha) and large reserves; foraging guilds of small to mediumsized, ground and above-ground insectivores were impoverished in degraded medium-sized and small remnants on private land. Almost the full range of woodland bird species was found at one or more sites, indicating their conservation value. However, some species were found in few sites or were only vagrants at a site. Active management will be needed to retain the current diversity of bird species in such heavily cleared landscapes.
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 ...
2018
Fragmentation-related increases in levels of predation at birds' nests, and changes to nest predator assemblages, have often been reported in Northern Hemisphere temperate forests. In many cases these changes have been attributed to an influx of matrix-associated avian predators from neighbouring agricultural or urbanised land. Well-documented increases in the abundance of avian nest predators, which are ecologically similar to those causing edge effects elsewhere, occur in Australian agricultural and urban habitats, and near edges within remnant eucalypt forests. Therefore, increases in levels of nest predation, similar to those occurring elsewhere, may be expected to occur near edges and within small remnant patches of Australian eucalypt forests. The same processes would not be expected to occur at the edges of eucalypt forests which border plantations of exotic Pinus tree species, because edge-related nest predation has seldom been reported in Northern Hemisphere temperate f...