Oliver D.L.,Biodiversity Conservation Section |
Lollback G.W.,University of New England of Australia
Pacific Conservation Biology | Year: 2010
This is the first Australian study to apply logistical modelling techniques to describe the breeding habitat selection of a widely dispersed, highly mobile, threatened bird species. Landscape and microhabitat structural attributes of breeding habitat occupied by the endangered Regent Honeyeater Anthochaera phrygia in the Bundarra-Barraba region of northern NSW were compared to those of unoccupied habitat using logistic regression modelling. Models containing landscapescale variables were best at explaining Regent Honeyeater presence. Regent Honeyeater occupation was negatively associated with the amount of woodland cover surrounding a site (1 km and 2 km radius) and distance to patch edge, and was positively associated with site connectivity and linear remnants. Linear, well-connected woodland patches surrounded by cleared grazing land are typical of the remnant native vegetation occupied by Regent Honeyeaters in the Bundarra-Barraba region. The landscape models developed here can be used to identify potential new sites for protection and rehabilitation, and to assess the suitability of unsurveyed or unoccupied sites for the release of captivelybred Regent Honeyeaters, which is identified as one of the priority recovery action for the species.
Val J.,2 Enterprise Way |
Oliver D.,Biodiversity Conservation Section |
Pennay M.,Landscape |
John M.,Charles Sturt University |
And 2 more authors.
Australian Zoologist | Year: 2012
Baseline surveys of reptiles, birds and small mammals that occur in Dune Mallee woodlands in the Lower Murray Darling catchment of south-western New South Wales were conducted at 60 sites between October 2007 and March 2008. These surveys comprise the first round of a catchmentwide monitoring programme to obtain a measure of the distribution and abundance of 21 priority threatened fauna species that inhabit Dune Mallee Woodlands. A total of 127 fauna species were recorded, which included 19 of the possible 21 threatened fauna species.The 127 species comprised 37 reptile species, 15 bat species, three small mammal species and 72 bird species.The mean species richness recorded at each three hectare survey site for birds was 14.7, reptiles 7.1, small ground dwelling mammals 0.5 and bats 3.0. Mean abundance for birds was 42.7, reptiles 13.1, small ground dwelling mammals 1.0 and microbats 3.7.These surveys represent the most comprehensive inventory of fauna of the Dune Mallee Woodlands of the Lower Murray Darling catchment. Furthermore, these surveys are a platform upon which to detect changes in abundance and persistence of priority threatened fauna species, as a way of measuring outcomes of property management agreements and offset reserves where land management has been enhanced by actions such as exotic herbivore removal and predator control.
Clemann N.,Arthur Rylah Institute for Environmental Research |
Scroggie M.P.,Arthur Rylah Institute for Environmental Research |
Smith M.J.,Arthur Rylah Institute for Environmental Research |
Peterson G.N.L.,Australian Department of Primary Industries and Fisheries |
Hunter D.,Biodiversity Conservation Section
Wildlife Research | Year: 2013
Context Because they are dependent on water, drought can have a deleterious impact on aquatic-breeding amphibians. One such species, the threatened growling grass frog (Litoria raniformis) occurs in south-eastern Australia, a region that has recently emerged from a decade-long, severe drought. Aims We aimed to identify features of drought refugia that facilitate persistence of L. raniformis, so as to provide guidance to natural-resource managers attempting to conserve populations of this species during drought. Methods We conducted repeat surveys for L. raniformis at 90 water bodies at the end of the 'millennium drought'. We recorded the following six environmental variables for each water body: origin (natural or not), type (lotic or lentic), proportion of aquatic vegetation cover, conductivity of water, riparian tree-canopy cover and distance to the nearest woodland. We used occupancy models to relate the presence of L. raniformis to these variables, while accounting for uncertain detection. Key results Water-body type (natural or artificial, lentic or lotic) had minimal influence on the probability of occupancy by L. raniformis. We found a strong negative relationship between occupancy and conductivity of water (a surrogate for salinity), and a positive relationship between occupancy and the proportion of aquatic vegetation. We found a negative relationship between detection and the extent of aquatic vegetation, and a mildly negative effect of canopy cover on occupancy. Conclusions Habitat characteristics are more important indicators of the quality of drought refugia for L. raniformis than is the type of water body per se. Consequently, we identified aquatic vegetation and salinity as important targets for management when planning the retention, creation or restoration of habitat to facilitate persistence of L. raniformis during drought. Implications Our results highlighted aquatic vegetation and water-quality parameters that are likely to facilitate the persistence of L. raniformis during drought. Assessing the effectiveness of our recommendations in an experimental framework would ensure that conservation management of this frog can be refined over time. © CSIRO 2013.
De Ruyck C.C.,University of Manitoba |
Duncan J.,Biodiversity Conservation Section |
Koper N.,University of Manitoba
Journal of Raptor Research | Year: 2012
Despite the widespread distribution of Northern Saw-whet Owls (Aegolius acadicus), little is known about their population numbers, trends, or migratory behavior within the Canadian prairies. We studied saw-whet owl population trends and migratory behavior in the north-central portion of the species range, and evaluated possible mechanisms explaining these observed patterns. We examined population trends, demographics, and migratory timing using 9 yr of banding data collected by the Delta Marsh Bird Observatory (DMBO) migration-monitoring program. We documented a regularly timed autumn migration consisting of primarily hatch-year males and females and adult females. Large annual fluctuations in owl abundance resulted in low statistical power to detect trends. We detected no significant trend in total owl numbers; however, we detected significant increases in the numbers of second-year and after-second-year females. We compared DMBO migration data to spring abundance data from the Manitoba and Saskatchewan Nocturnal Owl Survey (NOS). Significant positive correlations between the DMBO and NOS datasets provided confidence that our annual owl abundance estimates were representative of actual changes in owl abundance, and suggested that population trends were synchronized over large geographic regions spanning both provinces. © 2012 The Raptor Research Foundation, Inc.
Manning A.D.,Australian National University |
Gibbons P.,Australian National University |
Fischer J.,Lüneburg University |
Oliver D.L.,Biodiversity Conservation Section |
Lindenmayer D.B.,Australian National University
Animal Conservation | Year: 2013
Tree hollows are a critical breeding resource for many organisms globally. Where hollow-bearing trees are in decline, population limitation can be a serious conservation issue. A particular problem in addressing hollow limitation is the long time that hollows take to form. This means there can be a significant lag time between detecting a species' population decline and arresting the lack of hollows through reducing tree mortality and increasing regeneration. Once underway, declines of hollow-dependent species therefore can be difficult to halt. It is imperative that we identify and anticipate such future problems before they occur, and implement conservation action in advance. In this study, we use a novel application of an established modelling method to explore this issue and illustrate an 'early warning' approach, focusing on a case study of the vulnerable superb parrot Polytelis swainsonii from south-eastern Australia. The species is dependent on hollow-bearing trees for nesting that have a very long generation time (>120 years). Potential nest trees for the superb parrot are on a trajectory of decline. We modelled the future hollow resource for this species under different management scenarios including: (a) business-as-usual - that is, no further specific conservation action; (b) and (c) waiting until considerable further reductions (90 and 70%) in hollows before implementing conservation actions to redress loss of hollows; and (d) implementing enhanced conservation actions now to redress loss of hollows. We found that all scenarios except (d), 'conservation action now', resulted in substantial declines in potential nest trees, and came at significant opportunity cost in terms of reducing tree mortality and increasing tree regeneration. Delaying conservation action will greatly increase the long-term risk of extinction of hollow-dependent species such as the superb parrot. Predicting and slowing the decline in available hollows by early intervention and restoration management is critical, even where hollow-dependent species populations may appear to be secure in the short-term. © 2012 The Zoological Society of London.