Bird responses at inherent and induced edges in the Murray Mallee, South Australia. 1. Differences in abundance and diversity (original) (raw)
Related papers
Ecology, 2002
Ecotones have been considered as unique environments, and the concepts of edge effect and ecotonal species have been widely used, especially in avian community ecology. We studied the patterns of bird densities across heath-wood edges at replicated sites in three locations in southeastern Australia. Multivariate analysis showed that the bird community in the ecotone was intermediate between the heath and wood communities, indicating that the ecotone contained a mixing of species rather than a unique bird community. ANOVA showed a modest increase in bird density at the wood side of the ecotone, which may be partly due to sampling biases rather than to some inherent habitat value in the ecotone. The outstanding pattern was that bird density and species richness in the wood habitat were twice as high as in the heath habitat. Of a total of 86 species, 31 occurred in sufficient numbers to categorize according to their habitat association (generalist, or heath or wood specialist) and their density at the ecotone (ecotone neutral, ecotone shy, or ecotone conspicuous). Three of these were habitat-generalist-ecotone-neutral. Fourteen species were ecotone neutral but were habitat specialists on either the wood (13 spp.) or the heath (1 sp.). Three species were ecotone shy. Although 11 species were ecotone conspicuous, they also occurred in either heath or wood or both. Thus, no species could be categorized as entirely ecotonal. We conclude that there is little evidence from this or other studies of avian communities to support an edge effect of increased density and species richness, and no evidence of entirely ecotonal species.
Birds on edge: avian assemblages along forest-agricultural boundaries of central Victoria, Australia
Animal Conservation, 2001
Habitat clearance generally produces fragmented landscapes. A major consequence is the creation of large amounts of new 'edge habitat', often of a kind not previously existing, such as abrupt forestagricultural land interfaces. Much work from around the world suggests that proliferation of edge habitat seriously affects birds reliant on large forest blocks to persist, and the intrusion of edge specialists into areas they did not previously occupy. These processes often generate avifaunal gradients in which assemblages change from the interior to the edge. This effect is explored in the largest remnant block of box-ironbark forest of central Victoria, Australia (about 30,000 ha). Eight radially oriented survey lines were established around the periphery of the block. Along each survey line, five transects with long axes oriented parallel to the edge were positioned with midlines at 40 m, 160 m, 280 m and 400 m into the forest, and one transect 80 m into the agricultural land, yielding a total of 40 transects. Six identical transects were located deep within the forest (> 2 km). There was little evidence of a change in the avifauna from interior to edge, although mean richness was depressed in the edge habitats compared with forest interior transects. These results were essentially the same for 'all species' or 'forest dependent' species. Thus, there is little evidence for marked edge effects on the avifauna of these large forest blocks, although work in intermediate sized remnants (100-1000 ha) is needed to identify thresholds at which edge effects begin to be manifested.
Emu, 1999
We assayed nest predation as an edge effect, using artificial ground nests, at inherent (naturally occurring) and induced (human-created) edges in the Murray Mallee, South Australia. Nests were constructed at distances between 0-120 m away from habitat edges. The relative predation rate on nests generally increased close to induced edges with a significant difference (P < 0.05) recorded for two out of five experiments. Predation rate at inherent edges was similar from the edge to the interior, and was lower than that recorded at induced edges. Our results suggest that increased predator numbers, activity or efficiency at locating nests occurred close to the induced edges at our study sites.
Effects of landscape pattern on bird species distribution in the Mt. Lofty Ranges, South Australia
Landscape …, 2003
We assessed how well landscape metrics at 2, 5, and 10 km scales could explain the distribution of woodland bird species in the Mount Lofty Ranges, South Australia. We considered 31 species that have isolated or partially isolated populations in the region and used the Akaike Information Criterion to select a set of candidate logistic regression models. The 2 km distance was the most appropriate scale for a plurality of the species. While the total amount of area of native vegetation around a site was the most important determining factor, the effect of landscape configuration was also important for many species. Most species responded positively to area-independent fragmentation, but the responses to mean patch isolation and mean patch shape were more variable. Considering a set of candidate models for which there is reasonable support (Akaike weights > 0.10), 12 species responded negatively to landscapes with highly linear and isolated patches. No clear patterns emerged in terms of taxonomy or functional group as to how species respond to landscape configuration. Most of the species had models with relatively good discrimination (12 species had ROC values > 0.70), indicating that landscape pattern alone can explain their distributions reasonably well. For six species there were no models that had strong weight of evidence, based on the AIC and ROC criteria. This analysis shows the utility of the Akaike Information Criterion approach to model selection in landscape ecology. Our results indicate that landscape planners in the Mount Lofty Ranges must consider the spatial configuration of vegetation.
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.
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.
PLoS ONE, 2012
The value for biodiversity of large intact areas of native vegetation is well established. The biodiversity value of regrowth vegetation is also increasingly recognised worldwide. However, there can be different kinds of revegetation that have different origins. Are there differences in the richness and composition of biotic communities in different kinds of revegetation? The answer remains unknown or poorly known in many ecosystems. We examined the conservation value of different kinds of revegetation through a comparative study of birds in 193 sites surveyed over ten years in four growth types located in semi-cleared agricultural areas of south-eastern Australia. These growth types were resprout regrowth, seedling regrowth, plantings, and old growth. Our investigation produced several key findings: (1) Marked differences in the bird assemblages of plantings, resprout regrowth, seedling regrowth, and old growth.
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 ...
Austral Ecology, 2007
Forestry operations in jarrah forests of southwestern Australia use two types of selective logging, gaps which remove 85-95% of basal area and shelterwoods which remove 40-60% of basal area.These operations create considerable lengths of forestry edge (edges between logged and unlogged forest) each year, but their impact on the avifauna of the jarrah forest is unknown. Changes in bird density were examined along edges created by forestry operations in jarrah forests using a BACI design experiment. Bird densities were estimated on 1-ha plots that were surveyed three times per season, in three seasons both before and after logging. There was no evidence of edge effects at the community level; overall bird density and species richness did not changes along forestry edges. Scarlet robin (Petroica multicolor) abundance increased significantly along both gap and shelterwood edges, relative to controls. Apart from a probably spurious increase in density along gap edges by red-winged fairy-wrens (Malurus elegans), no other species showed a significant change in density along edges. There was also no difference in responses to gap and shelterwood edges, despite gaps removing more basal area than shelterwoods, suggesting that response to forestry edges in the jarrah forest may be threshold dependent, rather than increasing with increasing intensity of logging operations. Comparisons with other studies examining density changes along forestry edges in southwestern Australia suggest that density changes observed in this study are short-term in nature. The limited density change in avifauna along forestry edges is probably because selective logging practices were examined instead of clear-felling. Studies in the literature indicate that this pattern is likely to be true for many forest ecosystems.