Noisy Miner Research Articles

Win shifting in nectarivorous birds: selective inhibition of the learned win-stay response

A variety of nectarivorous species have demonstrated a bias to ‘win-shift’ (shift away from/avoid locations that have recently yielded food, as opposed to ‘win-stay’ behaviour where the animal returns to such locations). Since recently exploited ! owers contain no nectar, the win-shift bias is a candidate for an adaptive specialization of cognition. This bias tends to manifest as faster learning and/or better performance on a win-shift than a win-stay task. In standard win-shift/win-stay tasks (multiple two-phase trials where animals rst nd rewards in particular locations, and must subsequently avoid, or return to, such locations) noisy miners, Manorina melanocephala, and rainbow lorikeets, Trichoglossus haematodus, developed patterns of revisits/errors in the exploration phases that corresponded to the spatial contingency they experienced in the test phases: birds reinforced to shift revisited locations in the exploration phase that were unrewarded; birds reinforced to stay revisited rewarded ones. This was true even for birds that failed to shift or stay appropriately in the test phase itself. This suggests that the poorer performance of nectarivorous birds in win-stay than win-shift tasks may not be a consequence of an inability to learn the win-stay contingency. Our results suggest that these birds are equally sensitive to the win-shift and win-stay contingencies. This implies that, if the win-shift bias previously reported in nectarivorous birds is an example of a cognitive adaptation to the depleting nature of nectar, then the specially adapted mechanisms may have more to do with inhibition of the win-stay response than

A reverse keystone species affects the landscape distribution of woodland avifauna: a case study using the Noisy Miner (Manorina melanocephala) and other Australian birds

We explored the effects of a purported ‘reverse keystone species’, the Noisy Miner (Manorina melanocephala) using a long-term, large-scale dataset. Specifically, we identify whether this aggressive bird affects the landscape distribution patterns of other avifauna, by displacing them into, or restricting their distribution to, less productive areas, and in so doing, adheres to ‘isoleg theory’. We sought to determine the effect of abundance of the Noisy Miner on the abundance of other birds (individual species and groups), and determine whether that effect was consistent with varying site productivity, using a negative binomial distribution with a logarithmic link function, and an offset variable to account for variations in search effort. Relationships between abundance of Noisy Miners and habitat variables were examined using a Poisson distribution with a logarithmic link function scaled for extra-variation (quasi-Poisson regression). We demonstrate that when Noisy Miner abundance is low, many small passerine species are more abundant on high productivity sites. However, as Noisy Miner abundance increases, small passerine abundance decreases, with this decrease most apparent on productive sites. The same patterns were not evident for birds considered ‘non-competitors’ of the Noisy Miner. We identify that both site productivity and vegetation structure influence the abundance of the Noisy Miner. We reveal that the species increasingly tolerates ‘less desirable’ habitat attributes with increasing site productivity. The preference of the Noisy Miner for productive areas is likely to have deleterious impacts on the long-term survival and reproductive success of other Australian woodland bird species, many of which have already undergone severe declines.

A micro-geography of fear: learning to eavesdrop on alarm calls of neighbouring heterospecifics

Many vertebrates eavesdrop on alarm calls of other species, which is a remarkable ability, given geographical variation in community composition and call diversity within and among species. We used micro-geographical variation in community composition to test whether individuals recognize heterospecific alarm calls by: (i) responding to acoustic features shared among alarm calls; (ii) having innate responses to particular heterospecific calls; or (iii) learning specific alarm calls. We found that superb fairy-wrens (Malurus cyaneus) fled to cover to playback of noisy miner (Manorina melanocephala) aerial predator alarm calls only in locations where miners were present, suggesting that learning rather than acoustic structure determines response. Sites with and without miners were well within the dispersal distance of fairy-wrens, and philopatric males and dispersing females showed the same pattern, so that local genetic adaptation is extremely unlikely. Furthermore, where miners were present, fairy-wrens responded appropriately to different miner calls, implying eavesdropping on their signalling system rather than fleeing from miners themselves. Learned eavesdropping on alarm calls enables individuals to harvest ecologically relevant information from heterospecifics on an astonishingly fine spatial scale. Such phenotypic plasticity is valuable in a changing world, where individuals can be exposed to new species.

Tolerance of Auditory Disturbance by an Avian Urban Adapter, the Noisy Miner

AbstractUrbanization creates challenges for wildlife, most notably through changes in resource availability and the frequent occurrence of sensory disturbance. Some native species, however, have been able to exploit and thrive in urban environments. Research, in this regard, has mostly focused on the ecological conditions that have allowed such species to prosper. In contrast, less attention has been devoted to evaluating how they cope with human proximity and disturbance. In a field experiment on a successful Australian ‘urban adapter’, the Noisy miner, Manorina melanocephala, we compared tolerance of a loud, startling sound stimulus by urban and rural individuals. We found group size differences between birds occupying urban and rural sites: more urban birds came into the testing area in response to the initial alarm‐call playback compared with rural birds. Urban and rural birds also differed significantly in their behavioural response profile to the test sound stimulus. Nearly half (47.5%) of the rural, but only 22.5% of the urban birds took flight and of those that did, only 1 of 9 urban individuals retreated >5 m, compared with 13 of 19 rural birds. About one‐third of urban, but only 5% of rural individuals responded to the sound stimulus with aggressive displays. The most frequent response to the stimulus, irrespective of habitat type, was to remain near the sound source and engage in visual surveillance. The high frequency of this response in both urban and rural individuals suggested that most noisy miners were quite ‘bold’, a temperament trait that is likely to be important in successful urban colonization by birds.

When more is less: Urban remnants support high bird abundance but diversity varies

Urban remnant vegetation, especially where it occurs in public parks, allows for relatively easy access for ongoing biodiversity monitoring. However, relatively little baseline information on bird species distribution and abundance across a range of identifiable urban remnants appears in the published literature. We surveyed the relative abundance and distribution of birds across urban and suburban remnant vegetation in Melbourne, Australia. One hundred and six species were recorded, of which 98 were indigenous. Red wattlebirds had the highest mean relative abundance with 2.94 birds/ ha, followed by rainbow lorikeets (2.51), noisy miners (1.93), brown thornbills (1.75) and spotted doves (0.96). There was no obvious trend between overall relative abundance and the size of the remnant, in contrast to species richness which was positively correlated with remnant size. The data revealed that some species were either totally restricted to, or more abundant in, larger remnants and generally absent from smaller remnants. Some of the more common birds (crimson rosella, superb fairy-wren, spotted pardalote and black-faced cuckoo-shrike) recorded during this study were detected at similar densities to those found in comparable vegetation to the east of Melbourne within a largely forested landscape. Other species occurred at much lower densities (e.g., white-browed scrubwren, brown thornbill, eastern yellow robin and grey fantail) or had habitat requirements or ecological characteristics that could place them at risk of further decline or local extinction in the urban area. We identify a suite of bird species of potential conservation concern within Melbourne’s urban landscape. The establishment of repeatable, fixed-point, and long-term monitoring sites will allow for repeat surveying over time and provide an early warning of population declines, or conversely an indication of population increase for other species.

An overview of the ecology, management and conservation of Australia’s temperate woodlands

Summary Australia’s temperate woodlands are environments of cultural and ecological importance and significant repositories of Australia’s biodiversity. Despite this, they have been heavily cleared, much remaining vegetation is in poor condition and many species of plants and animals are threatened. Here, we provide a brief overview of key issues relating to the ecology, management and policy directions for temperate woodlands, by identifying and discussing ten themes. When addressing issues relating to the conservation and management of temperate woodlands, spatial scale is very important, as are the needs for a temporal perspective and a complementary understanding of pattern and process. The extent of landscape change in many woodland environments means that woodland patches, linear networks and paddock trees are critical elements, and that there can be pervasive effects from ‘problem’ native species such as the Noisy Miner (Manorina melanocephala). These consequences of landscape change highlight the challenge to undertake active management and restoration as well as effective monitoring and long‐term data collection. In developing approaches for conservation and management of temperate woodlands, it is essential to move our thinking beyond reserves to woodland conservation and management on private land, and recognise the criticality of cross‐disciplinary linkages. We conclude by identifying some emerging issues in woodland conservation and management. These include the need to further develop non‐traditional approaches to conservation particularly off‐reserve management; the value of documenting approaches and programmes that demonstrably lead to effective change; new lessons that can be learned from intact examples of temperate woodlands; and the need to recognise how climate change and human population growth will interact with conservation and management of temperate woodlands in future decades.

Movement and memory: different cognitive strategies are used to search for resources with different natural distributions

Recent attempts to integrate function and mechanism have resulted in an appreciation of the relevance of forager psychology to understanding the functional aspects of foraging behaviour. Conversely, an acknowledgement of the functional diversity of learning mechanisms has led to greater understanding of the adaptive nature of cognition. In this paper, we present data from three experiments suggesting that noisy miner birds use different cognitive strategies when searching for foods with different distributions. When searching for nectar, an immobile, readily depleted resource, birds spontaneously attend to fine-scale spatial information and use a spatial memory-based strategy that is efficient in a novel context and largely resistant to disruptions to movement. When searching for invertebrates, a mobile, clumped and cryptic resource, birds employ a strategy whose efficiency increases with increased task familiarity, is vulnerable to disruptions to their movement and may rely more on memory for movement rules than memory for location information. Previous reports of adapted cognition have reported performance differences between species (for example, better spatial cognitive performance in storing versus non-storing birds). Ours is the first study to demonstrate that differences in cognitive strategy (as opposed to just enhanced performance) occur within a single species in different foraging contexts. As well as providing an example of how specially adapted cognitive mechanisms might work, our data further emphasise the importance of jointly considering functional and mechanistic aspects to fully understand the adaptive complexities of behaviour.

Non‐lethal foraging by bell miners on a herbivorous insect: Potential implications for forest health

AbstractTree health is often negatively linked with the localized abundance of parasitic invertebrates. One group, the sap‐sucking psyllid insects (Homoptera: Psyllidae) are well known for their negative impact upon vegetation, an impact that often culminates in the defoliation and even death of hosts. In Australia, psyllid‐infested forest in poor health is also frequently occupied by a native honeyeater, the bell miner (Manorina melanophrys; Meliphagidae), so much so that the phenomenon has been dubbed ‘bell miner‐associated dieback’ (BMAD). Bell miners are thought to be the causative agent behind BMAD, in part because the species may selectively forage only upon the outer covering (lerp) exuded by psyllid nymphs, leaving the insect underneath to continue parasitizing hosts. As bell miners also aggressively exclude all other avian psyllid predators from occupied areas, these behavioural traits may favour increases in psyllid populations. We examined bell miner foraging behaviour to determine if non‐lethal foraging upon psyllid nymphs occurred more often than in a congener, the noisy miner (M. melanocephala; Meliphagidae). This was indeed the case, with bell miners significantly more likely to remove only the lerp covering during feeding, leaving the insect intact underneath. This arose from bell miners using their tongue to pry off the lerp cases, whereas noisy miners used their mandibles to snap at both the lerp and insect underneath. Furthermore, psyllids left behind following a bell miner foraging event were significantly more likely to be viable and regrow a lerp covering than those exposed by noisy miners. Together, this behaviour supports the theory that non‐lethal foraging behaviour of bell miners may contribute to high psyllid abundance, consistent with the mechanisms by which BMAD is thought to develop.

When a place is not a place: encoding of spatial information is dependent on reward type

AbstractThe adaptationist perspective investigates how an animal's cognition has been shaped by the informational properties of the environment. The information that is useful may vary from one context to another. In the current study we examine how manipulating the foraging context (the type of resource being foraged) could affect the way spatial information is used by the forager. Noisy miner birds (omnivorous honeyeaters) were given spatial working memory tasks in which they searched baited and unbaited feeders for either nectar or invertebrates. We hypothesised that noisy miners would encode the locations of baited and unbaited feeders equally well when foraging for nectar (all flowers, whether containing nectar or not are places to remember and avoid while foraging on a plant). When foraging for invertebrates, however, we predicted that noisy miner birds would not encode the locations of unbaited feeders as effectively as baited feeders (in a natural patch of invertebrates there is no cue to differentiate a point location where a prey item has not been found from the rest of the potentially homogenous patch). As predicted, birds foraging for invertebrates made more revisits to unbaited than baited feeders, with no such difference evident when birds were foraging for nectar.

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.

Impacts of grazing, selective logging and hyper‐aggressors on diurnal bird fauna in intact forest landscapes of the Brigalow Belt, Queensland

AbstractThe impact of forest management on diurnal bird assemblages and abundance was investigated in contiguous tracts of eucalypt forest in the Brigalow Belt Bioregion, south central Queensland. Sites were located across three levels of livestock grazing intensity and three levels of selective logging intensity within the most extensive habitat type, Corymbia citriodora‐dominant forest. We recorded a high rate of incidence and large numbers of the hyper‐aggressive noisy miner Manorina melanocephala (Passeriformes: Meliphagidae) at the majority of our survey sites, a phenomenon rarely reported in non‐cleared landscapes. As shown by numerous studies in fragmented landscapes, the distribution of this species in our study had a substantial negative effect upon the distribution of small passerine species. Noisy miners exerted the strongest influence upon small passerine abundance, and masked any forest management effects. However, key habitat features important for small passerines were identified, including a relatively high density of large trees and stems in the midstorey. Selective logging appeared to exert a minimal effect upon noisy miner abundance, whereas grazing intensity had a profound, positive influence. Noisy miners were most abundant in intensively grazed forest with minimal midstorey and a low volume of coarse woody debris. Higher road density in the forest landscape also corresponded with increased numbers of noisy miners. Reduction in grazing pressure in Brigalow Belt forests has the potential to benefit small passerine assemblages across large areas through moderating noisy miner abundance. The strong relationship between noisy miners and small passerines suggests that noisy miner abundance could act as an easily measured indicator of forest condition, potentially contributing to monitoring of forest management outcomes.

Does the presence of grevilleas and eucalypts in urban gardens influence the distribution and foraging ecology of Noisy Miners?

Noisy Miners have been described as a ‘reverse keystone’ species, aggressively excluding many bird species from an ever-increasing range of human-dominated landscapes. Understanding the factors influencing the distribution of Noisy Miners is therefore an important research priority. To determine whether a relationship exists between the distribution of Noisy Miners and the vegetation composition of suburban gardens, birds were surveyed according to a factorial design defined by the presence or absence of grevilleas and eucalypts. Contrary to popular expectation, there was no significant association between the abundance of Noisy Miners and the presence of hybrid grevilleas. However, there was a highly significant relationship between the abundance of Noisy Miners and the presence of eucalypts. Analysis of foraging time budgets showed that Noisy Miners consistently spent 25–30% of their foraging time feeding on grevilleas (only in sites in which they were present). Similar amounts of time were spent foraging in eucalypts or in flowering callistemons (when available), and the presence of grevilleas did not result in a reduction in overall commitments to foraging. Noisy Miners also spent substantial amounts of time foraging on open ground. This study does not support the notion that hybrid grevilleas have played a causal role in the spread of Noisy Miners across many suburban areas of eastern Australia. Our results are consistent with the hypothesis that it is the proliferation of lightly-treed open areas that favours the Noisy Miner.

Habitat preferences of the noisy miner (Manorina melanocephala) – a propensity for prime real estate?

AbstractThis study investigated habitat characteristics that have been postulated to influence the occurrence of noisy miners (Manorina melanocephala Family Meliphagidae). It builds on an earlier study that identified corners along remnant edges as important predictors of the presence of noisy miners in large blocks of remnant vegetation (>300 ha). Six habitat characteristics were recorded at 39 corner sites within the box‐ironbark region of Victoria. We failed to detect any significant effect of the density of understorey vegetation on the likelihood of noisy miners occupying a site, but this might have been an artefact of prolonged drought conditions. The most powerful predictors of the presence of noisy miners at remnant corners were found to be soil type and the proportion of canopy trees at a site that were yellow gum (Eucalyptus leucoxylon), with noisy miners being associated with deeper, more fertile soils and higher proportions of yellow gums present. As yellow gum is a prolific and reliable nectar producer, the inherent productivity of a site might be more important in determining the attractiveness of a site to noisy miners than structural attributes like the presence or absence of an understorey. Noisy miners are sedentary colonial birds that occupy year‐round territories, often at high densities. Sites capable of supporting such high density occupation year‐round might be limited to the most productive sites within the landscape. This productivity hypothesis has potentially profound implications for other woodland avifauna, as noisy miners might be excluding other woodland birds from some of the most fertile components of the landscape; components that are already rare in the box‐ironbark region due preferential clearing for agriculture at the time of settlement.

Interspecific competition and small bird diversity in an urbanizing landscape

Throughout eastern Australia, fragmentation and modification of eucalypt woodlands are causing declines in populations of woodland-dependent small passerines. Although agriculture is a major factor in these land use changes, development of peri-urban areas is also driving the simplification of habitat structure through removal of both native and weedy understorey species and the subdivision of remnant habitat. This study investigated the influence of habitat modification and fragmentation on birds in an urbanizing area of south east Queensland, Australia. The influence of spatial factors, such as surrounding vegetation cover, was considered alongside that of site-level habitat factors (vegetation structure) including interspecific competition from the noisy miner ( Manorina melanocephala). Spatial factors did not influence the abundance and species richness of small passerines, a group of conservation concern. However, site-level factors, specifically shrub density and interspecific competition from the noisy miner, had a substantial influence on small passerine species richness and abundance. The density of shrubs (which consisted mainly of the introduced weed Lantana camara) had a strong positive relationship with small passerines while the abundance of noisy miners had a strong negative influence. Consequently, protection of vegetation with an intact shrub layer in this developing area is essential for many small birds of conservation significance. Removal of weedy understorey plants should be accompanied by replacement with native shrubs. The results of the study emphasize that factors other than the spatial distribution of vegetation in the landscape need to be considered in order to develop appropriate conservation strategies.

Nesting, foraging and aggression of Noisy Miners relative to road edges in an extensive Queensland forest

Increased abundance of Noisy Miners (Manorina melanocephala), a large, aggressive honeyeater, is one of the most important mechanisms through which habitat fragmentation and degradation threaten populations of eastern Australian woodland birds. In inland Queensland, however, Noisy Miners dominate avian assemblages throughout extensive forest areas as well as fragmented landscapes, and our understanding of the factors influencing their behaviour and habitat selection in such relatively intact landscapes is limited. I investigated how road edges influenced Noisy Miners by comparing the species’ aggressive and foraging behaviour, and location of nests, between road-edge and interior transects in a southern Queensland forest. I also investigated Noisy Miner foraging microhabitat preferences and targets of aggression. Noisy Miner nests were more likely to be located near to road edges, but foraging and aggressive interactions occurred with similar frequency near and far from road edges. Such interactions selectively targeted close competitors and a nest predator. Most foraging activity was in the canopy, and selectively within ironbarks (Eucalyptus spp.), suggesting that higher densities of Noisy Miners in more open areas of the forest are unlikely to be related to facilitation of ground-foraging activity. Despite some evidence of a preference for nesting near road openings, road edges do not appear to influence Noisy Miners as strongly as edges between forest and agricultural land do elsewhere in eastern Australia.

Interspecific competition and conservation management of continuous subtropical woodlands

Context. Large reserves have potential to provide important refugia for fragmentation-sensitive species as they lack many aspects of habitat degradation associated with fragmented regions. However, large reserves often have a history of deleterious management practices that may affect the restoration of biological diversity. One significant symptom of habitat fragmentation and disturbance in Australia is the increased occurrence of the aggressive noisy miner (Manorina melanocephala). In Queensland, however, even large continuous areas of woodland appear to be dominated by the noisy miner. Aims.We examined the severity of this phenomenon by identifying the interactions between habitat structure, noisy miner abundance and avian assemblages in a private and a public conservation reserve in central Queensland. We investigated potential constraints on restoration of avian diversity including: (1) how changes in habitat structure as a result of grazing by feral animals and burning regimes affect bird assemblages; and (2) how the noisy miner impacts on avian assemblages in these unfragmented woodlands. Methods. Bird surveys and habitat assessments were conducted in 49 sites on three separate occasions. Fire history and intensity of grazing pressure were determined for each site with direct and indirect observations. Sampling for lerp from insects of the family Psyllidae was also undertaken during the survey periods. A Bayesian model averaging (BMA) approach was used to model avian response to each of the habitat variables. Key results. The noisy miner dominated most of the study area, reducing small passerine abundance and species richness. Noisy miners were advantaged where shrub cover was low and feral grazing impacts were evident. Disturbance factors including recent wildfire and heavy grazing strongly reduced small passerine bird richness and abundance. Conclusions. Reducing the abundance of this ‘reverse keystone’ species requires control of feral herbivore populations and modification of fire regimes to achieve a mosaic including patches with a dense shrub layer. Implications. Deleterious interactions with competitive native species, such as noisy miners, are obstacles to bird conservation not only in fragmented landscapes but also in large, continuous woodland areas. Land mangers of protected areas need to be aware of shifts in interactions among native species driven by habitat disturbance, which may ultimately affect conservation outcomes.

Edge geometry influences patch-level habitat use by an edge specialist in south-eastern Australia

We investigated patterns in habitat use by the noisy miner (Manorina melanocephala) along farmland-woodland edges of large patches of remnant vegetation (>300 ha) in the highly fragmented box-ironbark woodlands and forests of central Victoria, Australia. Noisy miners exclude small birds from their territories, and are considered a significant threat to woodland bird communities in the study region. Seventeen different characteristics of edge habitat were recorded, together with the detection or non-detection of noisy miners along 129 500-m segments of patch edge. Habitat characteristics ranged from patch-level factors related to patch-edge geometry to site-level floristic factors. Backward (stepwise) logistic regression analyses were used to identify habitat characteristics that were associated with the occupancy of a site by noisy miners. After accounting for the effects of spatial autocorrelation on the occurrence of noisy miners along edges, we identified projections of remnant vegetation from the patch edge into the agricultural matrix (e.g., corners of patches, peninsulas of vegetation) and clumps of trees in the agricultural matrix within 100 m of the edge as significant predictors of the occupancy of edges by noisy miners. This relationship was also confirmed in two other geographically and floristically distinct habitats within Victoria. The use of edges with projections by noisy miners may confer advantages in interspecific territorial defence. In light of these results, we advocate revegetation strategies that attempt to enclose projections within 100 m of the edge, with fencing placed out to this new boundary, to reduce the likelihood of colonisation and domination of an edge by noisy miners. Our study highlights the need for greater consideration to be given to the patterns in habitat use by aggressive edge specialists, particularly in relation to patch-edge geometry and other human-induced components of landscapes.

The effect of Noisy Miners on small bush birds: an unofficial cull and its outcome

This paper documents the bird community in a small (~15 ha) patch of remnant woodland New South Wales sheep? wheat belt (i) before Noisy Miners Manorina melanocephala were abundant in the patch (1972-79), (ii) after a dense miner colony became established (1980-1990), (iii) after the miners were removed (1991?92) and, subsequently, (iv) while extensive, dense plantings of native trees became established (1992-2006). Bird species richness in the patch was, respectively, 64, 18, 45 and 83 species in each time period. Totals for small (<120 g) bush birds, mostly insectivorous passerines, were 26, 0, 22 and 46 species in the respective time periods. Although this was an unofficial, unreplicated and uncontrolled activity, the results support those of previous similar studies that indicate that Noisy Miners are a major contributor to the local decline of many woodland birds. The results also affirm the value of a shrub layer to small birds.

Food-specific spatial memory biases in an omnivorous bird

The tendency of nectarivorous birds to perform better on tasks requiring them to avoid previously rewarding locations (to win-shift) than to return to them (win-stay) has been explained as an adaptation to the depleting nature of nectar. This interpretation relies on the previously untested assumption that the win-shift tendency is not associated with food types possessing a different distribution. To test this assumption, we examined the specificity of this bias to different food types in an omnivorous honeyeater, the noisy miner (Manorina melanocephala). As predicted, we found that the win-shift bias was sensitive to foraging context, manifesting only in association with foraging for nectar, not with foraging for invertebrates.

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.