Detection and habitat use of the rufous bristlebird (Dasyornis broadbenti) in coastal heathland, in south-western Victoria, Australia

The Rufous Bristlebird (Dasyornis broadbenti) is a sedentary, ground-dwelling passerine of southern Australia, which is listed as nationally vulnerable, and as near-threatened (lower risk) in Victoria. The species inhabits a variety of vegetation, including shrub thickets in coastal gullies to heathlands on limestone cliffs. This study aimed to assess the size, distribution and habitat use of a population of the subspecies D. b.  broadbenti at Portland in south-western Victoria. Monthly surveys (2002–03) were conducted on foot for 1 h after official sunrise and 1 h before official sunset, and presence of Bristlebirds recorded using vocalisations and sightings. Observations outside of the survey times were also recorded to estimate the size of territories and core area of occupancy. To quantify habitat preferences, vegetation composition and structure were measured in areas where Bristlebirds were present, as well as surrounding areas where they were not detected. The population in the survey areas was estimated at between 70 and 86 individuals in the 170-ha survey area. The estimated size of territories of eight selected pairs of Bristlebirds ranged from 0.5 to 3 ha, with core areas of occupancy ranging from 0.2 to 0.6 ha. During the nesting season (August November) Bristlebirds were detected at greater frequencies in the core area of occupancy within each territory. Significant associations were found between the presence of Bristlebirds and floristic associations dominated by the native environmental weeds Acacia sophorae and Leptospermum laevigatum. Bristlebird presence was significantly positively correlated with increasing vegetation density in the mid-canopy level (80–120 cm) indicating that vegetation structure is a key factor in habitat use.

Distribution and abundance of the white-faced storm petrel (Pelagodroma marina) in Victoria

Habitat loss and modification is a major factor driving reductions of seabird populations. The white-faced storm petrel (Pelagodroma marina) is restricted to three breeding colonies within Victoria: Mud Islands and South Channel Fort in Port Phillip Bay, and Tullaberga Island off Mallacoota. The numbers of storm petrels breeding on Mud Islands and South Channel Fort have declined considerably, possibly a result of the significant vegetation changes, together with increases in local populations of other species of birds, most notably, silver gulls (Larus novaehollandiae). On Mud Islands the breeding area available to the storm petrels appears to be limited by the recent arrival of the Australian white ibis (Threskoirnis molucca), and straw-necked ibis (T. spinicollis) which now breed on the islands in large numbers (approximately 15,000 pairs). The impact of these changes on the storm petrels is poorly understood. The current status of storm petrels at Tullaberga Island is unknown. This study estimated the size of the breeding population at all three sites by determining burrow densities, and a burrow-scope was used to determine occupancy. Burrow density was found to be related to vegetation type and other habitat factors. This study has highlighted important information on the breeding habitat of the white-faced storm petrel and the implications for management are discussed.

Benthic habitat mapping in coastal waters of south–east Australia

The Victorian Marine Mapping Project will improve knowledge on the location, spatial distribution, condition and extent of marine habitats and associated biodiversity in Victorian State waters. This information will guide informed decision making, enable priority setting, and assist in targeted natural resource management planning. This project entails benthic habitat mapping over 500 square kilometers of Victorian State waters using multibeam sonar, towed video and image classification techniques. Information collected includes seafloor topography, seafloor softness and hardness (reflectivity), and information on geology and benthic flora and fauna assemblages collectively comprising habitat. Computerized semi-automated classification techniques are also being developed to provide a cost effective approach to rapid mapping and assessment of coastal habitats.

Habitat mapping is important for understanding and communicating the distribution of natural values within the marine environment. The coastal fringe of Victoria encompasses a rich and diverse ecosystem representative of coastal waters of South-east Australia. To date, extensive knowledge of these systems is limited due to the lack of available data. Knowledge of the distribution and extent of habitat is required to target management activities most effectively, and provide the basis to monitor and report on their status in the future.

Coastal marine habitat mapping using multi-beam acoustics, video data and a decision tree classifier on the temperate south-east Australian continental shelf

In this habitat mapping study, multi-beam acoustic data are integrated with extensive, precisely geo-referenced video validation data in a GIS environment to classify benthic substrates and biota at a 33km2 site in the near shore waters of Victoria, Australia. Using an automated decision-tree classification method, 5 representative biotic groups were identified in the Cape Nelson survey area using a combination of multi-beam bathymetry, backscatter and derivative products. Rigorous error assessment of derived, classified maps produced high overall accuracies (>85%) for all mapping products. In addition, a discrete multivariate analysis technique (kappa analysis) was used to assess classification accuracy. High-resolution (2.5m cell-size) representation of sea floor morphology and textural characteristics provided by multi-beam bathymetry and backscatter datasets, allowed the interpretation of benthic substrates of the Cape Nelson site and the communities of sessile organisms that populate them. Non-parametric multivariate statistical analysis (ANOSIM) revealed a significant difference in biotic composition between depth strata, and between substrate types. Incorporated with other descriptive measures, these results indicate that depth and substrate are important factors in the distributional ecology of the biotic communities at the Cape Nelson study site. BIOENV analysis indicates that derivatives of both multi-beam datasets (bathymetry and backscatter) are correlated with distribution and density of biotic communities. Results from this study provide new tools for research and management of the coastal zone.

Predictive distribution models and their application in wildlife conservation

Wildlife managers are often faced with the difficult task of determining the distribution of species, and their preferred habitats, at large spatial scales. This task is even more challenging when the species of concern is in low abundance and/or the terrain is largely inaccessible. Spatially explicit distribution models, derived from multivariate statistical analyses and implemented in a geographic information system (GIS), can be used to predict the distributions of species and their habitats, thus making them a useful conservation tool. We present two such models: one for a dasyurid, the Swamp Antechinus (Antechinus minimus), and the other for a ground-dwelling bird, the Rufous Bristlebird (Dasyornis broadbenti), both of which are rare species occurring in the coastal heathlands of south-western Victoria. Models were generated using generalized linear modelling (GLM) techniques with species presence or absence as the independent variable and a series of landscape variables derived from GIS layers and high-resolution imagery as the predictors. The most parsimonious model, based on the Akaike Information Criterion, for each species then was extrapolated spatially in a GIS. Probability of species presence was used as an index of habitat suitability. Because habitat fragmentation is thought to be one of the major threats to these species, an assessment of the spatial distribution of suitable habitat across the landscape is vital in prescribing management actions to prevent further habitat fragmentation.

Habitat requirements of the yellow-footed antechinus (Antechinus flavipes) in box–ironbark forest, Victoria, Australia

Understanding the habitat requirements of a species is critical for effective conservation-based management. In this study, we investigated the influence of forest structure on the distribution of the yellow-footed antechinus (Antechinus flavipes), a small dasyurid marsupial characteristic of dry forests on the inland side of the Great Dividing Range, Australia. Hair-sampling tubes were used to determine the occurrence of A. flavipes at 60 sites stratified across one of the largest remaining tracts of dry box–ironbark forest in south-eastern Australia. We considered the role of six potential explanatory variables: large trees, hollow-bearing trees, coppice hollows, logs, rock cover and litter. Logistic regression models were examined using an information-theoretic approach to determine the variables that best explained the presence or absence of the species. Hierarchical partitioning was employed to further explore relationships between occurrence of A. flavipes and explanatory variables. Forest structure accounted for a substantial proportion of the variation in occurrence of A. flavipes between sites. The strongest influence on the presence of A. flavipes was the cover of litter at survey sites. The density of hollow-bearing trees and rock cover were also positive influences. The conservation of A. flavipes will be enhanced by retention of habitat components that ensure a structurally complex environment in box–ironbark forests. This will also benefit the conservation of several threatened species in this dry forest ecosystem.

Seasonal and habitat related variation in the health of tropical savanna finches

Differences in habitat quality can affect the abundance, distribution, and physiological status of wild birds. In Australia’s tropical savannas, grass finches live in habitats of varying land use and resultant habitat quality. Recent studies have documented regional declines in the abundance and distribution of small granivorous birds in areas affected by cattle grazing, urban development, and changes in fire frequency and timing. Small birds, especially semi-nomadic species of grass-finches, are extremely difficult to survey for changes in local abundance and productivity. Consequently, we are using a range of physiological measures to determine the susceptibility of populations to decline. We present the preliminary findings of a study using multiple condition indices to describe the health of five grass finch species living in a variety of savanna habitats. Our early results suggest that simple body condition measures such as bird mass, muscle contour, and fat storage, are not always sensitive enough to identify subtle differences in the health of individuals and populations. Measures of haematological health state, stress, and background nutritional status of finch populations appear to be associated with seasonal and site differences where body condition measures or abundance surveys would have failed to present a coherent picture. We are using habitat characteristics important to these species to help explain the differences in the health of finch populations across the North.

Habitat use by five sympatric Australian freshwater crayfish species (Parastacidae)

1. The Grampians National Park in Victoria is a 'hot spot' for freshwater crayfish diversity, with seven species from six genera occurring in sympatry. Few studies have examined how multiple species of freshwater crayfish co-exist across landscapes consisting of a mosaic of perennial and seasonal habitats. Despite their endemicity and likely key role in freshwaters, the ecology and biology of these crayfish remains unknown.

2. This study determined the distribution and habitat use of five crayfish species (Euastacus bispinosus, Cherax destructor, Geocharax falcata, Gramastacus insolitus and Engaeus lyelli). Seasonal sampling surveys ascertained whether crayfish distribution was related to habitat type, environmental or physicochemical variables, catchment or season.

3. Distribution was directly related to habitat type and the environmental and physicochemical variables that characterised habitats. Engaeus lyelli, G. falcata and G. insolitus occurred predominantly in floodplain wetlands and flooded vegetation habitats, E. bispinosus occurred only in flowing soft-sediment channels and C. destructor was found in all catchments and habitat types studied. Gramastacus insolitus co-occurred with G. falcata at all sites except two, so no distinct habitat separations were apparent for these two species.

4. A high percentage cover of boulders was the best indicator of crayfish absence, and discriminated between habitat types and crayfish species: it was probably a surrogate for a larger range of environmental and physicochemical variables. Catchment and season did not affect crayfish distribution.

5. These crayfish species varied in their degree of habitat specialisation from strongly generalist (C. destructor) to occupying only a specific habitat type (E. bispinosus). Some species appeared specialised for seasonal wetlands (G. insolitus and G. falcata). Overlap in site occupancy also varied: G. insolitus and G. falcata distributions were strongly associated, whereas C. destructor appeared to occur opportunistically across habitats, both alone and co-occurring with all the other species.

6. Management strategies to conserve multiple species of crayfish co-existing within landscapes will need to incorporate a range of perennial and seasonal habitat types to ensure sufficient space is available for species to maintain different occupancy patterns. Given that water resources are under increasing pressure and are strongly regulated within the Grampians National Park, this may present a conservation challenge to water managers in this location.

Endemic freshwater finfish of Asia : distribution and conservation status

Freshwater finfish species richness and level of endemism in East, and South and South-East Asia that included 17 nations were studied using available databases, and included nation-wise distribution, habitat types, and conservation status. The number of endemic finfish species in the region was 559, belonging to 47 families. Families Cyprinidae and Balitoridae accounted for 43.5% and 16.2% of the total number of endemic species in the region, respectively, followed by Sisoridae (25), Gobiidae (20), Melanotaeniidae (19), and Bagridae (16), and the other 41 families had at least one endemic species. Nation-wise the most number of endemic freshwater finfish species occur in India (191), followed by China (88), Indonesia (84), and Myanmar (60). In India, the endemic species accounted for 26.4% of the native freshwater fish fauna, followed by South Korea (16.9%), the Philippines, (16.3%) and Myanmar (15.7%).

Statistically significant relationships discerned between the number of indigenous and endemic species richness to land area (X_la in 10³ km²) of the nations in the region were, Y_in = 218.961 Ln(X_la) – 843.1 (R² = 0.735; P < 0.001) and Y_e = 28.445 Ln X_la−134.47 (R² = 0.534; P < 0.01), respectively, and between indigenous and endemic species richness was Y_e = 0.079X_n− 1.558 (R² = 0.235; P < 0.05).

The overall conservation status of endemic finfish in Asia was satisfactory in that only 92 species were in some state of vulnerability, of which 37 species (6.6%) are endangered or critically endangered. However, the bulk of these species (83.7%) were cave- and or lake-dwelling fish. However, nation-wise, the endemic freshwater finfish fauna of the Philippines and Sri Lanka, based on the imperilment index, were found to be in a highly vulnerable state. Among river basins, the Mekong Basin had the highest number of endemic species (31.3%). The discrepancies between databases are highlighted and the need to consolidate information among databases is discussed. It is suggested that the Mekong Basin be considered as a biodiversity hotspot, and appropriate management strategies be introduced in this regard.

Habitat suitability for marine fishes using presence-only modelling and multibeam sonar

Improved access to multibeam sonar and underwater video technology is enabling scientists to use spatially-explicit, predictive modelling to improve our understanding of marine ecosystems. With the growing number of modelling approaches available, knowledge of the relative performance of different models in the marine environment is required. Habitat suitability of 5 demersal fish taxa in Discovery Bay, south-east Australia, were modelled using 10 presence-only algorithms: BIOCLIM, DOMAIN, ENFA (distance geometric mean [GM], distance harmonic mean [HM], median [M], area-adjusted median [Ma], median + extremum [Me], area-adjusted median + extremum [Mae] and minimum distance [Min]), and MAXENT. Model performance was assessed using kappa and area under curve (AUC) of the receiver operator characteristic. The influence of spatial range (area of occupancy) and environmental niches (marginality and tolerance) on modelling performance were also tested. MAXENT generally performed best, followed by ENFA-GM and -HM, DOMAIN, BIOCLIM, ENFA-M, -Min, -Ma, -Mae and -Me algorithms. Fish with clearly definable niches (i.e. high marginality) were most accurately modelled. Generally, Euclidean distance to nearest reef, HSI-b (backscatter), rugosity and maximum curvature were the most important variables in determining suitable habitat for the 5 demersal fish taxa investigated. This comparative study encourages ongoing use of presence-only approaches, particularly MAXENT, in modelling suitable habitat for demersal marine fishes.

Habitat fragmentation and landscape change

This chapter begins by summarizing the conceptual approaches used to understand conservation in fragmented landscapes. We then examine the biophysical aspects of landscape change, and how such change affects species and communities, posing two main questions: (i) what are the implications for the patterns of occurrence of species and communities?; and (ii) how does landscape change affect processes that influence the distribution and viability of species and communities. The chapter concludes by identifying the kinds of actions that will enhance the conservation of biota in fragmented landscapes.

Occurrence and distribution of established and new introduced bird species in north Sulawesi, Indonesia

Distributional and habitat information on eight introduced bird species in north Sulawesi, Indonesia, is presented. The accounts are based on our observations as well as being gathered from published sources and unpublished trip reports. Three species (Sulphur-crested Cockatoo Cacatua galerita, Sooty-headed Bulbul Pycnonotus aurigaster and Red-collared Dove Steptopelia tranquebarica) have not previously been reported in north Sulawesi in the published literature, while the continued presence and status of Java Sparrow Padda oryzivora, Zebra Dove Geopelia striata and Rock Dove Columba livia was considered uncertain in the published literature. Further work is required systematically to document the distribution, status and spread of introduced species in the north and other parts of Sulawesi—an imperative from both an economic and conservation perspective.

Large-herbivore distribution and abundance : intra-and interspecific niche variation in the tropics

Determining the biological and environmental factors that limit the distribution and abundance of organisms is central to our understanding of the niche concept and crucial for predicting how species may respond to large-scale environmental change, such as global warming. However, detailed ecological information for the majority of species has been collected only at a local scale, and insufficient consideration has been given to geographical variation in intraspecific niche requirements. To evaluate the influence of environmental and biological factors on patterns of species distribution and abundance, we conducted a detailed, broadscale study across the tropical savannas of northern Australia on the ecology of three large, sympatric marsupial herbivores (family Macropodidae): the antilopine wallaroo (Macropus antilopinus), common wallaroo (M. robustus), and eastern grey kangaroo (M. giganteus). Using information on species abundance, climate, fire history, habitat, and resource availability, we constructed species' habitat models varying from the level of the complete distribution to smaller regional areas. Multiple factors affected macropod abundance, and the importance of these factors was dependent on the spatial scale of analyses. Fire regimes, water availability, geology, and soil type and climate were most important at the large scale, whereas aspects of habitat structure and interspecific species abundance were important at smaller scales. The distribution and abundance of eastern grey kangaroos and common wallaroos were strongly influenced by climate. Our results suggest that interspecific competition between antilopine wallaroos and eastern grey kangaroos may occur. The antilopine wallaroo and eastern grey kangaroo (grazers) preferred more nutrient-rich soils than the common wallaroo (grazer/browser), which we relate to differences in feeding modes. The abundance of antilopine wallaroos was higher on sites that were burned, whereas the abundance of common wallaroos was higher on unburned sites. Future climate change predicted for Australia has the capacity to seriously affect the abundance and conservation of macropod species in tropical savannas. The results of our models suggest that, in particular, the effects of changing climatic conditions on fire regimes, habitat structure, and water availability may lead to species declines and marked changes in macropod communities.

Separating the influences of environment and species interactions on patterns of distribution and abundance : competition between large herbivores

* 1
Much recent research has focused on the use of species distribution models to explore the influence(s) of environment (predominantly climate) on species’ distributions. A weakness of this approach is that it typically does not consider effects of biotic interactions, including competition, on species’ distributions.
* 2
Here we identify and quantify the contribution of environmental factors relative to biotic factors (interspecific competition) to the distribution and abundance of three large, wide-ranging herbivores, the antilopine wallaroo (Macropus antilopinus), common wallaroo (Macropus robustus) and eastern grey kangaroo (Macropus giganteus), across an extensive zone of sympatry in tropical northern Australia.
* 3
To assess the importance of competition relative to habitat features, we constructed models of abundance for each species incorporating habitat only and habitat + the abundance of the other species, and compared their respective likelihoods using Akaike's information criterion. We further assessed the importance of variables predicting abundance across models for each species.
* 4
The best-supported models of antilopine wallaroo and eastern grey kangaroo abundance included both habitat and the abundance of the other species, providing evidence of interspecific competition. Contrastingly, models of common wallaroo abundance were largely influenced by climate and not the abundance of other species. The abundance of antilopine wallaroos was most influenced by water availability, eastern grey kangaroo abundance and the frequency of late season fires. The abundance of eastern grey kangaroos was most influenced by aspects of climate, antilopine wallaroo abundance and a measure of cattle abundance.
* 5
Our study demonstrates that where census and habitat data are available, it is possible to reveal species’ interactions (and measure their relative strength and direction) between large, mobile and/or widely-distributed species for which competition is difficult to demonstrate experimentally. This allows discrimination of the influences of environmental factors and species interactions on species’ distributions, and should therefore improve the predictive power of species distribution models.

Understanding fish-habitat associations using video observations and sonar imaging

This thesis was motivated by the increasing role of species distribution models in managing marine fishes and their habitats. These models provided new information about fish-habitat associations. However, models are potentially influenced by fish behaviour towards underwater video systems.