Bristlebird

About: Bristlebird is a research topic. Over the lifetime, 14 publications have been published within this topic receiving 311 citations. The topic is also known as: Bristlebird.

Spatial prediction of rufous bristlebird habitat in a coastal heathland: a GIS-based approach

Abstract: 1. To develop a conservation management plan for a species, knowledge of its distribution and spatial arrangement of preferred habitat is essential. This is a difficult task, especially when the species of concern is in low abundance. In south-western Victoria, Australia, populations of the rare rufous bristlebird Dasyornis broadbenti are threatened by fragmentation of suitable habitat. In order to improve the conservation status of this species, critical habitat requirements must be identified and a system of corridors must be established to link known populations. A predictive spatial model of rufous bristlebird habitat was developed in order to identify critical areas requiring preservation, such as corridors for dispersal. 2. Habitat models generated using generalized linear modelling techniques can assist in delineating the specific habitat requirements of a species. Coupled with geographic information system (GIS) technology, these models can be extrapolated to produce maps displaying the spatial configuration of suitable habitat. 3. Models were generated using logistic regression, with bristlebird presence or absence as the dependent variable and landscape variables, extracted from both GIS data layers and multispectral digital imagery, as the predictors. A multimodel inference approach based on Akaike’s information criterion was used and the resulting model was applied in a GIS to extrapolate predicted likelihood of occurrence across the entire area of concern. The predictive performance of the selected model was evaluated using the receiver operating characteristic (ROC) technique. A hierarchical partitioning protocol was used to identify the predictor variables most likely to influence variation in the dependent variable. Probability of species presence was used as an index of habitat suitability. 4. Negative associations between rufous bristlebird presence and increasing elevation, 'distance to cree', 'distance to coast' and sun index were evident, suggesting a preference for areas relatively low in altitude, in close proximity to the coastal fringe and drainage lines, and receiving less direct sunlight. A positive association with increasing habitat complexity also suggested that this species prefers areas containing high vertical density of vegetation. 5. The predictive performance of the selected model was shown to be high (area under the curve 0·97), indicating a good fit of the model to the data. Hierarchical partitioning analysis showed that all the variables considered had significant independent contributions towards explaining the variation in the dependent variable. The proportion of the total study area that was predicted as suitable habitat for the rufous bristlebird (using probability of occurrence at a ≥0·5 level ) was 16%. 6. Synthesis and applications. The spatial model clearly delineated areas predicted as highly suitable rufous bristlebird habitat, with evidence of potential corridors linking coastal and inland populations via gullies. Conservation of this species will depend on management actions that protect the critical habitats identified in the model. A multi-scale approach to the modelling process is recommended whereby a spatially explicit model is first generated using landscape variables extracted from a GIS, and a second model at site level is developed using fine-scale habitat variables measured on the ground. Where there are constraints on the time and cost involved in measuring finer scale variables, the first step alone can be used for conservation planning.

Post-fire recovery of eastern bristlebirds (Dasyornis brachypterus) is context-dependent

Abstract: In late December 2003, a wildfire in the Jervis Bay region of New South Wales burned through an area that previously supported a large population of the endangered eastern bristlebird (Dasyornis brachypterus). The eastern bristlebird has been described as fire-sensitive, and fire is implicated in the decline of the species. The frequency of occurrence of bristlebirds was investigated in the second week after the fire in a range of sites varying in fire intensity. Bristlebirds were found in burned habitats but were less common in the sites that were more intensely burnt. Bristlebirds had been surveyed along transects in this area two months before this fire and were surveyed again 1, 9 and 13 months after the fire. Compared with prefire numbers, bristlebird numbers decreased in burnt areas after the fire and increased in unburnt areas. This pattern was evident for up to nine months after the fire, after which bristlebird numbers returned towards prefire levels in both burnt and unburnt vegetation. This is in contrast to some previous research on bristlebirds and fire. We suggest that bristlebirds avoided the fire by moving to unburnt areas and returned later when conditions were more suitable. We consider that the apparently slight impact of this fire on bristlebirds was due to the close proximity of unburnt habitat and other refuges. The response of bristlebirds and presumably other birds to fire is likely to be strongly context-dependent, so fire management may be able to be designed so as to be compatible with the conservation of local bristlebird populations.

Population genetic structure of the endangered Eastern Bristlebird, Dasyornis brachypterus; implications for conservation

Abstract: For species that are habitat specialists or sedentary, population fragmentation may lead to genetic divergence between populations and reduced genetic diversity within populations, with frequent inbreeding. Hundreds of kilometres separate three geographical regions in which small populations of the endangered Eastern Bristlebird, Dasyornis brachypterus, a small, ground-dwelling passerine that occurs in fire-prone bushland in eastern Australia, are currently found. Here, we use mitochondrial and microsatellite DNA markers to: (i) assess the sub-specific taxonomy designated to northern range-edge, and central and southern range-edge D. brachypterus, respectively, and (ii) assess levels of standing genetic variation and the degree of genetic subdivision of remnant populations. The phylogenetic relationship among mtDNA haplotypes and their spatial distribution did not support the recognised subspecies boundaries. Populations in different regions were highly genetically differentiated, but in addition, the two largest, neighboring populations (located within the central region and separated by ~50 km) were moderately differentiated, and thus are likely closed to migration (microsatellites, F ST = 0.06; mtDNA, F ST = 0.12, Θ ST = 0.08). Birds within these two populations were genotypically diverse and apparently randomly mating. A long-term plan for the conservation of D. brachypterus’s genetic diversity should consider individual populations as separate management units. Moreover, managers should avoid actively mixing birds from different populations or regions, to conserve the genetic integrity of local populations and avoid outbreeding depression, should further translocations be used as a recovery tool for this species.

Translocation of the Eastern Bristlebird 2: applying principles to two case studies

Abstract: Summary The Eastern Bristlebird (Dasyornis brachypterus) is an endangered endemic passerine of south-eastern Australia. The re-establishment of extirpated populations through translocation was identified as a key action in New South Wales to address the threats to this species associated with habitat fragmentation and widespread and frequent fire. At Jervis Bay during 2003–2005, 50 birds were translocated from Bherwerre Peninsula to Beecroft Peninsula. In the Illawarra in 2008, 50 birds were translocated from Barren Grounds Nature Reserve to Cataract. At Jervis Bay, monitoring indicated that after 7 years, (i) there was no detectable impact on the source population from the removal of birds and (ii) the count at Beecroft Peninsula was 94 birds, with dispersal up to 6.3 km from the release point. In the Illawarra, (i) the source population was recovering 3 years post-removal and (ii) the maximum count at Cataract was 15 birds after 3.5 years, including evidence of breeding, and after 3 years, the maximum dispersal was 7 km from the release point. Both translocations adhered to five key principles as follows. (i) Feasibility analysis prior to each project was favourable. (ii) For 17 pre-stated criteria for success, 14 and 10, respectively, were met for Jervis Bay and Illawarra. (iii) Financial accountability was achieved with detailed statements showing budgets of $201k and $92k, respectively, for Jervis Bay and Illawarra. (iv) Ecological research was incorporated into both projects. (v) The results of each project are progressively being published. The re-introduction at Jervis Bay has succeeded, and we are optimistic about the Illawarra re-introduction.

Translocation of the Eastern Bristlebird and factors associated with a successful program

Abstract: In the ongoing concern for the conservation of biodiversity around the globe, intensive, hands-on management of threatened species is becoming commonplace. The translocation of organisms to establish, re-establish or augment populations is one of the intensive strategies being used. This thesis explores the contemporary use of translocation in conservation, with a focus on the reintroduction of the Eastern Bristlebird (Dasyornis brachypterus) as a case study. Translocation can be defined as the movement of living organisms from one area to free release in another. It is becoming increasingly common in the conservation of threatened species of a range of taxa around the world. Translocations have generally suffered from high failure rates, which have been mainly attributed to low habitat quality of the release site, a small number of individuals released, ignoring species-specific behaviours, poor management of the original threats to the species and stochastic environmental events. Aspects that have been associated with success include high habitat quality of the release site, reintroduction into part of the former range of the species, large number of individuals released and the use of a wild source population. Recent reviews have identified five key aspects of translocation projects that are required for a well-formed translocation program. These are the completion of a feasibility analysis, the use of criteria by which to assess success, the inclusion of experimental designs, financial accountability, and the effective communication of outcomes. The bristlebird is an endangered Australian passerine. It is a small cover-dependent, semi-flightless bird that is restricted to a few isolated populations over a large geographic