Brown Treecreeper Research Articles

Multilocus phylogeography, population genetics and niche evolution of Australian brown and black-tailed treecreepers (Aves:Climacteris)

AbstractThe Carpentarian barrier across north-eastern Australia is a major biogeographic barrier and a generator of biodiversity within the Australian Monsoonal Tropics. Here we present a continent-wide analysis of mitochondrial (control region) and autosomal (14 anonymous loci) sequence and indel variation and niche modelling of brown and black-tailed treecreepers (Climacteris picumnus and Climacteris melanurus), a clade with a classic distribution on either side of the Carpentarian barrier. mtDNA control region sequences exhibited reciprocal monophyly and strong differentiation (Fst = 0.91), and revealed a signature of a recent selective sweep in C. picumnus. A variety of tests support an isolation-with-migration model of divergence, albeit with low levels of gene flow across the Carpentarian barrier and a divergence time between species of ~1.7–2.8 Mya. Palaeoecological niche models show that both range size as measured by available habitat and estimated historical population sizes of both species declined in the past ~600 kyr and that the area of interspecific range overlap was never historically large, perhaps decreasing opportunities for extensive gene flow. The relatively long divergence time and low opportunity for gene flow may have facilitated speciation more so than in other co-distributed bird taxa across the Australian Monsoonal Tropics.

Long-term monitoring of nest boxes and nest logs in a tree-hollow depleted box–ironbark forest in north-eastern Victoria

Forest and woodland areas that have suffered historic degradation of habitat are likely to have reduced populations of tree-hollow dependent wildlife. We investigated the frequency of use of small-entry nest boxes installed 3 m high and vertical nest logs installed 1–3 m high, over 10–30 years in box–ironbark forest in north-east Victoria. Mammals were the dominant users of the nest boxes. Squirrel gliders and sugar gliders collectively used >75% of boxes and brush-tailed phascogales used >30% of boxes. Birds used the nest boxes on just two occasions. Brown treecreepers were the dominant users of the nest logs, with 48 breeding events across 30% of 105 nest logs. Turquoise parrots bred in the logs on five occasions. Gliders used 31% and phascogales 16% of the nest logs. These mammals were directly observed more frequently in the nest boxes than in the nest logs. Our findings show that mammals and birds preferred morphologically different hollows. Further research into the influence of different artificial hollow design elements is required. Nest boxes and nest logs required infrequent maintenance that was easily sustained over time. Our results suggest that tree-hollow dependent wildlife can benefit from restoration of their breeding and shelter sites.

Integrated models to support multiobjective ecological restoration decisions.

Many objectives motivate ecological restoration, including improving vegetation condition, increasing the range and abundance of threatened species, and improving species richness and diversity. Although models have been used to examine the outcomes of ecological restoration, few researchers have attempted to develop models to account for multiple, potentially competing objectives. We developed a combined state-and-transition, species-distribution model to predict the effects of restoration actions on vegetation condition and extent, bird diversity, and the distribution of several bird species in southeastern Australian woodlands. The actions reflected several management objectives. We then validated the models against an independent data set and investigated how the best management decision might change when objectives were valued differently. We also used model results to identify effective restoration options for vegetation and bird species under a constrained budget. In the examples we evaluated, no one action (improving vegetation condition and extent, increasing bird diversity, or increasing the probability of occurrence for threatened species) provided the best outcome across all objectives. In agricultural lands, the optimal management actions for promoting the occurrence of the Brown Treecreeper (Climacteris picumnus), an iconic threatened species, resulted in little improvement in the extent of the vegetation and a high probability of decreased vegetation condition. This result highlights that the best management action in any situation depends on how much the different objectives are valued. In our example scenario, no management or weed control were most likely to be the best management options to satisfy multiple restoration objectives. Our approach to exploring trade-offs in management outcomes through integrated modeling and structured decision-support approaches has wide application for situations in which trade-offs exist between competing conservation objectives.

The anatomy of a failed offset

Biodiversity offsetting is widely applied but its effectiveness is rarely assessed. We evaluated the effectiveness of a nest box program intended to offset clearing of hollow-bearing trees associated with a freeway upgrade in southern Australia. The offset targeted three threatened vertebrates: squirrel glider (Petaurus norfolcensis), brown treecreeper (Climacteris picumnus) and superb parrot (Polytelis swainsonii). Clearing led to the loss of 587 tree hollows and the offset was the placement of an equivalent number of nest boxes in nearby woodland (1:1 ratio). Of these, we monitored 324 nest boxes in six sample periods between 2010 and 2013, yielding 2485 individual checks of nest boxes.For the three target species, we found: (1) no records of nest box use by the superb parrot, (2) two records of the brown treecreeper (0–0.76% of accessible nest boxes used per survey period), and (3) seven records of use of nest boxes by the squirrel glider (0–2.1% of accessible nest boxes used per survey period). Rates of nest box use by the superb parrot and squirrel glider were markedly lower than rates of use of hollow-bearing trees observed in other investigations. Low levels of use by target species coupled with the extent of nest box attrition suggest the offset program will not have counterbalanced the loss of the hollow-bearing trees.We make suggestions for improving future offset programs including a greater emphasis on: (1) avoiding impacts on hollow-bearing trees; (2) offset effectiveness as a measure of compliance; and (3) using realistic offset ratios.

Habitat Selection and Behaviour of a Reintroduced Passerine: Linking Experimental Restoration, Behaviour and Habitat Ecology

Habitat restoration can play an important role in recovering functioning ecosystems and improving biodiversity. Restoration may be particularly important in improving habitat prior to species reintroductions. We reintroduced seven brown treecreeper (Climacteris picumnus) social groups into two nature reserves in the Australian Capital Territory in south-eastern Australia. This study provided a unique opportunity to understand the interactions between restoration ecology, behavioural ecology and habitat ecology. We examined how experimental restoration treatments (addition of coarse woody debris, variations in ground vegetation cover and nest box installation) influenced the behaviour and microhabitat use of radio-tracked individuals to evaluate the success of restoration treatments. The addition of coarse woody debris benefited the brown treecreeper through increasing the probability of foraging on a log or on the ground. This demonstrated the value of using behaviour as a bio-indicator for restoration success. Based on previous research, we predicted that variations in levels of ground vegetation cover would influence behaviour and substrate use, particularly that brown treecreepers would choose sites with sparse ground cover because this allows better access to food and better vigilance for predators. However, there was little effect of this treatment, which was likely influenced by the limited overall use of the ground layer. There was also little effect of nest boxes on behaviour or substrate use. These results somewhat confound our understanding of the species based on research from extant populations. Our results also have a significant impact regarding using existing knowledge on a species to inform how it will respond to reintroduction and habitat restoration. This study also places great emphasis on the value of applying an experimental framework to ecological restoration, particularly when reintroductions produce unexpected outcomes.

Causes of reintroduction failure of the brown treecreeper: Implications for ecosystem restoration

Reintroductions are conducted to re-establish a self-sustaining population of a species and contribute to ecosystem restoration. The brown treecreeper (Climacteris picumnus) reintroduction into two nature reserves in the Australian Capital Territory in south-eastern Australia failed to meet its predetermined criteria for success. This occurred despite prior habitat restoration within the reserves where reintroduction occurred. Low survival of reintroduced brown treecreepers, particularly due to predation by native predators, has previously been highlighted as a key factor in the failure of the programme. We compared bird behaviour and habitat characteristics between the reintroduction reserves and the sites where brown treecreepers were sourced (which support stable brown treecreeper populations). We did not identify an indication of significantly higher predation pressure in the reintroduction reserves in comparison with the source sites. However, our results revealed that reintroduced individuals may be more vulnerable to predation because of an increased flight time to reach a refuge area. This was a result of a significantly lower number of refuge areas in logs and trees and a higher number of shrubs (which may obstruct escape paths and hinder detection of predators) in the reintroduction reserves compared with the source sites. We identified a lower ground foraging habitat quality in the reintroduction reserves because of lower numbers of ant mounds and lower areas of forageable ground. However, brown treecreepers were able to disperse extensively throughout the reserves and settle in areas with generally higher-quality foraging habitat. Therefore, the negative effect of low ground foraging habitat quality would have been most pronounced immediately after release. This study emphasizes the inherent complexities of species reintroductions and ecosystem restoration. Despite experimental restoration activities within the reintroduction reserves, there were still deficiencies in habitat quality. We emphasize that further habitat restoration is required within these reserves to achieve more complete restoration.

Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual’s dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual’s gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species’ requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species’ ecology.

The anatomy of a failed reintroduction: a case study with the Brown Treecreeper

Reintroductions are often used to re-establish a self-sustaining population of a species as a conservation method. Despite their prevalence, few reintroductions have followed recent international recommendations to publish details such as appropriate site-selection, criteria for success and experimental analyses of the reintroduction. Here we report on the first experimental reintroduction of the Brown Treecreeper (Climacteris picumnus), a ground-foraging Australian woodland passerine. Seven social groups (43 individuals) were released into two nature reserves in south-eastern Australia. Using a robust comparison of habitat-restoration treatments, we evaluate the influence of these treatments and demographic parameters of the Brown Treecreepers on measures of success of the reintroduction. Although individual Brown Treecreepers lost an average of 5.82% of their bodyweight during translocation, survival during the first 24 h and the first 3 days after reintroduction was high and was not significantly influenced by habitat treatments at the release site. There was, however, evidence of high levels of mortality in the first 2 months after release, but there was no influence of sex or age on apparent survival. These apparent losses may be attributable to longer-term effects of translocation stress, lack of familiarity with habitat or insufficient effectiveness of restoration treatments. Although this reintroduction appears to have failed, we present details on all aspects of the reintroduction to provide vital information and lessons learned regarding procedures and outcomes.

Changes in the avifauna of Cape York Peninsula over a period of 9 years: the relative effects of fire, vegetation type and climate

An essential component of conservation science is repeated surveys over time to monitor species that might be responding to local factors, such as land management, or more broadly to global change. A systematic survey of the avifauna of Cape York Peninsula was conducted in the late 1990s and early 2000s providing an ideal basal dataset for measuring change in the avifauna. A subset (n > 600) of these sites, primarily within savanna landscapes, was selected for re-survey in 2008 to investigate changes in bird communities on Cape York Peninsula. Changes in mean species richness varied across the study area (decreases in 59 grid cells and increases in 43) with no apparent pattern. Significant change in reporting rates was recorded in 30 species. Four sedentary and highly detectable species declined (Bar-shouldered Dove, Brown Treecreeper, Sulphur-crested Cockatoo and Pale-headed Rosella) and five increased (Peaceful Dove, Pheasant Coucal, Weebill, White-throated Honeyeater and Yellow Oriole). Habitat preference for the species that showed change remained relatively stable between the two survey periods. Some species that were recorded in very low numbers in the original survey and are considered to be threatened (Brown Treecreeper, Black-faced Woodswallow) remained in very low numbers or decreased in our survey suggesting that there has been no regional recovery of these species. Long-term monitoring can describe important patterns of species change over time, though in the case of large, highly seasonal environments like the tropical savannas, signals of change may manifest over decades rather than annually.

Dispersal behaviour of Brown Treecreepers predicts functional connectivity for several other woodland birds

The persistence of native species in fragmented landscapes is dependent on dispersal or foraging movements between habitat patches, which may be limited. Although corridors have been heralded as solutions, their effectiveness depends on species’ movement behaviour, which has rarely been studied. We previously analysed dispersal movements of Brown Treecreepers (Climacteris picumnus), concluding that scattered trees may provide greater connectivity than corridors, and the length of corridors and size of any gaps within may be more important than corridor width. However, conclusions from a single species may not be representative. Here, we analyse dispersal movements of two sedentary birds—Eastern Yellow Robins (Eopsaltria australis) and White-throated Treecreepers (Cormobates leucophaeus)—and foraging movements of two semi-nomadic birds—Fuscous Honeyeaters (Lichenostomus fuscus) and White-plumed Honeyeaters (L. penicillatus). Despite differences in their ecologies and purpose of movements, we found the movement strategies of these species at the local landscape scale were similar. The types of connectivity used and gap distances crossed were similar to those for Brown Treecreepers, strengthening our understanding of how to provide connectivity. We suggest that decision rules for movement have been shaped over evolutionary time by variability in the landscape, so movement behaviour may be less species-specific than previously assumed.

Extinction debt or habitat change? – Ongoing losses of woodland birds in north-eastern New South Wales, Australia

The loss, fragmentation and degradation of native vegetation are major causes of loss of biodiversity globally. Extinction debt is the term used to describe the ongoing loss of species from fragmented landscapes long after the original loss and fragmentation of habitat. However, losses may also result from habitat changes that are unrelated to fragmentation, which reduce breeding success and recruitment. Many woodland birds have declined in fragmented landscapes in Australia, probably due to loss of small, isolated populations, though the ecological processes are poorly understood. We record the progressive regional loss of two ground-foraging, woodland birds, the Brown Treecreeper Climacteris picumnus and Hooded Robin Melanodryas cucullata, in northern New South Wales, over 30 years. This has happened despite most habitat loss occurring over 100 years ago, suggesting the payment of an extinction debt. Our observations suggest that several ecological processes, caused by habitat loss, fragmentation or degradation, and operating over different time scales, have led to both species’ declines. Female Brown Treecreepers disperse poorly among vegetation remnants, leaving only males in isolated populations, which then go extinct. In contrast, Hooded Robins suffer high nest predation in fragmented landscapes, producing too few recruits to replace adult mortality. Foraging by both species may also be affected by regrowth of ground vegetation and shrubs. We found little support for a major role played by drought, climate change or aggressive Noisy Miners Manorina melanocephala. We propose that both extinction debt in the classical sense and ongoing habitat change frequently contribute to species’ decline in modified landscapes. Management to arrest and reverse such declines needs to consider these multiple causes of decline. For instance, reconnecting isolated populations may be inadequate alone, and activities such as appropriate grazing, fires and the addition of woody debris may also be required.

Positive effects of helpers on reproductive success in the brown treecreeper and the general importance of future benefits

1. Numerous studies of cooperatively breeding species have tested for effects of helpers on reproductive success to evaluate hypotheses for the evolution of cooperation, but relatively few have used experimental or statistical approaches that control for the confounding effects of breeder and territory quality. 2. In the brown treecreeper Climacteris picumnus, most helpers are male offspring of the breeding pair that have delayed dispersal. We analysed 5 years of data (97 territory-years) using hierarchical linear modelling to test for effects of helpers on reproductive success while controlling for confounding factors. 3. The number of helpers was related positively to reproductive success even after controlling for differences between territories and breeders. A threshold effect was observed, with success increasing most with the presence of a second helper (i.e. at group size of four). 4. Feeding at the nest was one mechanism responsible for this effect, as larger groups had higher total feeding rates at all nesting stages. Higher total feeding rates, as well as higher feeding rates by helpers, were correlated in turn with greater reproductive success. 5. An analysis of the effects of helper feeding rate on reproductive success in groups with just one helper produced only weak support for a positive effect of helpers. Controlled comparisons of this kind utilize only a small fraction of the total data available and thus have limited statistical power compared to hierarchical or mixed-modelling. 6. A number of hypotheses to explain the evolution and maintenance of helping behaviour are consistent with our results for brown treecreepers including kin selection and hypotheses based on future direct benefits. 7. A previous synthesis of studies of helper effects that controlled for confounding factors suggested a pattern in which male helpers rarely have positive effects on reproductive success. However, revising that synthesis to include recent hierarchical or mixed-modelling studies suggests that helpers of both sexes usually have positive effects, and that the relative importance of future direct benefits may have been underestimated.

Eucalypt plantings on farms benefit woodland birds in south‐eastern Australia

Abstract Most of the original forest and woodland cover on the western slopes of New South Wales and the northern plains of Victoria has been cleared for agriculture (wheat, sheep and cattle) and what remains is highly fragmented and modified by a long history of disturbance. Over the past three decades, native eucalypt trees and shrubs have been planted extensively in a part of this region to provide a range of environmental benefits. Our aim was to determine the extent to which these plantings could improve biological diversity in agricultural landscapes in south‐eastern Australia and to identify the variables influencing their effectiveness. We sampled birds at 120 sites encompassing the range of available patch sizes, stand ages, floristic and structural conditions, and habitat attributes for revegetated areas and remnants of native vegetation, and we compared these to nearby paddocks. Eucalypt plantings were found to provide significant improvements in bird population density compared with cleared or sparsely treed paddocks, and mixed eucalypt and shrub plantings had similar bird communities to remnant native forest and woodland in the region. Birds displayed a strong response to patch size, with both larger (≥5–20 ha) eucalypt plantings and larger (≥5–20 ha) remnants having more species and more individuals per unit area than smaller (<5 ha) patches of these vegetation types. Older (10–25 years) plantings had more bird species and individuals than young (<10 years) plantings. The distance from remnant forest and woodland (habitat connectivity) appeared to be an important variable influencing bird species richness in eucalypt plantings. The main differences were due to the greater numbers of species classified as woodland‐dependent in the larger‐sized patches of plantings and remnants. Eucalypt plantings provided useful habitat for at least 10 declining woodland‐dependent species, notably for the Speckled Warbler, Red‐capped Robin and Rufous Whistler. The Brown Treecreeper and Dusky Woodswallow appeared to be the species most limited by the extent of remnant forest and woodland in the region. Plantings of all shapes and sizes, especially those larger than 5 ha, have an important role to play in providing habitat for many bird species. Restoration efforts are more likely to be successful if eucalypt plantings are established near existing remnant vegetation.

Inducing whole‐assemblage change by experimental manipulation of habitat structure

1. Habitat structure long has been identified as a primary factor influencing local assemblage composition. Most evidence has been in the form of correlations of species occurrence and assemblage composition over a range of habitats, with experimental verification of relationships being relatively uncommon because of the difficulties of enacting precise manipulations of habitat structure. 2. Fallen timber (also known as coarse or large woody debris) is one of the few habitat-structural elements in forests and woodlands that can be manipulated with relatively high precision. We report on manipulations of wood-loads on 30 experimental 1-ha plots in floodplain forests of northern Victoria, Australia, over 4 years (one pre- and three post-manipulation). 3. We show that very high wood-loads (80 Mg ha(-1)) and intermediate wood-loads derived from tree crowns (40 Mg ha(-1)) increase species richness (all species and ground-foraging species) and numbers of birds (all species and ground-foraging species) relative to the control plots. 4. Three bird species consistently increased most following manipulations: white-plumed honeyeater Lichenostomus penicillatus (Gould 1837) (fam. Meliphagidae), brown treecreeper Climacteris picumnus (Temm. & Laug. 1824) (fam. Climacteridae) and yellow rosella Platycercus elegans flaveolus (Gould 1837) (fam. Psittacidae). The honeyeater is not considered as a ground or fallen timber dependent species, while the treecreeper and rosella both are regarded as being dependent on ground-layer structure. 5. Fallen timber management needs to be considered in a landscape and temporal context for improving conservation of avian biodiversity.

Comparative demography of treecreepers: evaluating hypotheses for the evolution and maintenance of cooperative breeding

Despite the long history of research on cooperative breeding, few comparative studies have been undertaken to test hypotheses for the evolution and maintenance of delayed dispersal using data from both cooperative and noncooperative species. We tested predictions about demographic differences between cooperative and noncooperative species based on four hypotheses for the evolution of delayed dispersal: the ecological constraints hypothesis, the life history hypothesis, the broad constraints hypothesis and the benefits-of-philopatry hypothesis. We controlled for phylogeny and habitat by comparing sympatric populations of two Australasian treecreepers (Climacteridae): the cooperatively breeding brown treecreeper, Climacteris picumnus, and the pair-breeding white-throated treecreeper, Cormobates leucophaea, which has lost cooperative breeding despite phylogenetic conservation of the trait in most of the treecreeper lineage. Our data failed to support nearly every prediction of the constraints and life history hypotheses. The two species had similar levels of constraints and similar life histories, and any significant differences were in the opposite direction to those predicted. However, the cooperative species was characterized by significantly higher variance in reproductive success as a result of group size effects, supporting the benefits-of-philopatry hypothesis as an explanation for the maintenance of delayed dispersal. Our comparisons also suggest that the benefits parents derive from group living determine whether or not they tolerate offspring on the natal territory. We therefore propose an antipredator tactics hypothesis in which delayed dispersal will initially evolve or be lost in particular taxa depending on the relative costs and benefits of vigilance and active defence versus concealment-based antipredator tactics.

Habitat selection in two Australasian treecreepers: what cues should they use?

When habitats differ in quality, individuals may attempt to maximise fitness through habitat selection. However, complete tests of habitat selection are rare, in part because many studies fail to quantify fitness consequences of habitat choice. We studied habitat selection of Australasian treecreepers (Passeriformes: Climacteridae) in temperate eucalypt woodland by examining the influence of habitat characteristics and confounding factors on annual reproductive success. In the pair-breeding White-throated Treecreeper (Cormobates leucophaeus), older females and territories with fewer stumps and less woody debris produced more young, possibly because these habitat characteristics lead to reduced conflict with Brown Treecreepers (Climacteris picumnus). In the cooperatively breeding Brown Treecreeper, larger groups and territories with lower densities of shrub, moderate levels of ground cover, and greater amounts of foraging substrate produced more fledglings, whereas territories with greater invertebrate biomass produced more independent young. Predicted annual reproductive success in the best territory was up to two offspring more than predicted success in the worst territory; thus, treecreepers would benefit from selecting good quality habitat. However, complete tests of habitat selection need to evaluate whether dispersers actively sample multiple habitats and choose the best available, and thus whether individual-level processes determine large-scale patterns of distribution and abundance. These results also suggest that current conservation efforts to exclude grazing from remnant patches of eucalypt woodland may be inappropriate if not used in conjunction with other management actions, because such exclusion may dramatically increase shrub density and ground cover. Alternative management tools need to be investigated that will maintain a mosaic of microhabitat types and thus protect the eucalypt woodland ecosystem, not just a few of its species.

Longer-term response to experimental manipulation of fallen timber on forest floors of floodplain forest in south-eastern Australia

There often are substantial accumulations of fallen timber (logs, large boughs) in many woodlands and forests around the world. However, fallen timber has become a target for removal for use as fuel or for management actions, such as fuel-reduction burning. Many silvicultural practices, such as fast harvesting rotations, coppicing and debris burning prior to re-sowing/re-planting, lead to much reduced fallen-timber loads. Many studies show the ecologically important role fallen timber plays, so its removal is likely to have adverse ecological outcomes. It has previously been shown that a specialized forager on fallen timber, the brown treecreeper Climacteris picumnus, responded strongly over a short-term (20 mo) to a meso-scale (34 ha) manipulation of fallen-timber loads in river red gum Eucalyptus camaldulensis forest in northern Victoria, Australia [Mac Nally, R., Horrocks, G., Pettifer, L., 2002a. Experimental evidence for beneficial effects of fallen timber in forests. Ecol. Appl. 12, 1588–1594]. There were substantially more birds in all treatments in which loads were increased to 40 Mg/ha or more, elevated from averages of ca. 20 Mg/ha across the southern Murray-Darling Basin. Sites were revisited 3 years after the manipulation was conducted and I show here that the changes in density have been sustained. These results suggest that increased fallen-timber loads ≥40 Mg/ha are preferred by the vulnerable treecreeper, and that the bird's responses reported previously were not transient. These elevated densities may translate into increased reproductive success of the treecreepers because larger groupings in this and related cooperative breeders produce more young. I conclude by outlining options for management of fallen timber to provide greater chances of viability for the species.

Characterization of microsatellite loci in the brown treecreeper (Climacteris picumnus) and cross‐species amplification in the white‐throated treecreeper (Cormobates leucophaeus)

AbstractEight polymorphic microsatellite markers were developed for the brown treecreeper, Climacteris picumnus. The number of alleles ranged from three to 25 per locus with observed heterozygosities between 0.05 and 0.76. Seven of the eight primer pairs also amplified polymorphic microsatellite loci in the white‐throated treecreeper (Cormobates leucophaeus). These markers are likely to be useful for population genetic and parentage studies in any of the Australasian treecreepers (Climacteridae) and are the first genetic markers developed for any member of this passerine family.

The influence of livestock grazing and weed invasion on habitat use by birds in grassy woodland remnants

Remnants of native vegetation in regions dominated by agriculture are subject to degradation, especially by livestock grazing and weed invasion. Ground-foraging birds are amongst the most threatened bird groups in Australia, and these agents of degradation might be contributing to their decline by causing a reduction in food availability. We studied the foraging behaviour and microhabitat use of seven species of ground-foraging insectivores in south-eastern Australian buloke woodland remnants with native, grazed and weedy ground-layers. If birds must resort to using more energetically expensive prey-attack manoeuvres, or selectively use substrates and microhabitats that are less available in degraded habitats, then such degradation is likely to be negatively impacting on these species. We found evidence of a negative impact of one or both of these types of degradation on five of the seven bird species. Three species that employ a range of foraging manoeuvres to attack prey used potentially more energetically expensive aerial manoeuvres significantly more frequently in weedy remnants than in remnants with a native or grazed ground layer. Red-capped robins Petroica goodenovii and brown treecreepers Climacteris picumnus both selectively foraged near trees in grazed sites, and hooded robins Melanodryas cucullata, red-capped robins and willie wagtails Rhipidura leucophrys avoided foraging in microhabitats with a high percentage cover of exotic grasses in weedy sites. Brown treecreepers were also less likely to be present in weedy sites that had been protected from grazing than in either grazed or native sites. These results suggest that although grazing appears to have a detrimental impact on foraging habitat of ground-foraging birds, the exclusion of livestock grazing from previously disturbed buloke remnants alone is not adequate to restore habitat values for ground-foraging birds. A conservation strategy for this habitat type should consider the exclusion of heavy grazing from sites with an intact cryptogamic crust and the management of weeds in disturbed remnants, potentially through the use of carefully controlled light grazing.

Response of vertebrates to fenceline contrasts in grazing intensity in semi‐arid woodlands of eastern Australia

Abstract Changes in the abundance, species richness and assemblage composition of vertebrates due to grazing by domestic stock were investigated in the semi‐arid woodlands of eastern Australia. Analyses were based on the differences found at 10 fenceline contrast sites. Two species of amphibians, 22 species of reptiles and two species of small mammal were captured in pit traps during the surveys. Kangaroos (red and eastern grey), sheep, goats and 66 species of birds were recorded along line transects. Analyses revealed that abundance of diurnal reptiles and species richness of diurnal reptiles and birds were significantly lower on heavily grazed sites than they were on lightly grazed sites. At a local scale, the gecko, Gehyra variegata, was more abundant where grazing was heavier, while Diplodactylus conspicillatus, Diplodactylus steindachneri and Rhynchoedura ornata responded to variables indirectly related to grazing intensity (kangaroo density, sheep and goat dung mass and sheep density, respectively). Birds more commonly sighted on lightly grazed areas than heavily grazed areas were the apostlebird, brown treecreeper, crested bellbird, grey butcherbird, hooded robin, jacky winter, little woodswallow, Australian magpie‐lark, mulga parrot, splendid wren, white‐browed treecreeper and yellow‐rumped thornbill. Birds more commonly sighted on heavily grazed areas than on lightly grazed areas were the Australian raven and chestnut‐crowned babbler. Most variation in species composition between sites was due to spatial separation and no regional‐level indicator species of grazing were evident. A combination of direct grazing‐related changes (e.g. loss of ground cover) and indirect effects of the pastoral industry (e.g. introduction of artificial sources of water) lead to changes in fauna at different scales of analysis across regions.