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Interspecific owever, empirical evidence of the resource availability competition is an essential element of the evolution of species and can strongly influence the abundance and distribution of species. Where competition interacts with anthropogenic habitat modification, this natural ecosystem process can become a threatening process. Understanding the mechanisms behind competition in such cases is essential for the formulation of cost-effective management responses for biodiversity conservation. According to the resource availability hypothesis of competition, interference competition limits access to resources by species vulnerable to such aggression and wastes energy in evasive responses. Studying competition is notoriously difficult, however, empirical evidence of the resource availability theory is limited, and there are few published experimental studies showing such an effect at larger scales. We present the results of a controlled and replicated empirical study of interference competition at a landscape scale. We removed an aggressive, overabundant native bird, Manorina melanocephala (noisy miner), whose interference competition is a threatening process for small woodland birds in the highly modified agricultural landscapes of eastern Australia. We monitored foraging and harassment rates of small woodland birds before and after removal to indicate if levels of interference competition changed. Due to unexpected immediate recolonisation, abundance of M. melanocephala in treatment sites declined by only 34% relative to control sites. Twenty-four bird species displayed aggressive behaviour towards other birds and 41 bird species were victims of aggression. Manorina melanocephala was responsible for 66% of all aggressive interactions. After removal, we recorded a doubling in foraging rate of small woodland birds in treatment compared to control sites. This appears to confirm the resource availability hypothesis of competition. Paradoxically, however, increased foraging was not accompanied by a decline in harassment. Low detection rates of harassment of small woodland birds, combined with the modest reduction in abundance of M. melanocephala, make it difficult to draw firm conclusions about the relationship between rates of harassment and rates of foraging.

Interactions between competing species may be intensified when they are restricted to small patches of remnant habitat, potentially increasing physiological stress in individuals. The effects of interspecific competition on stress in wildlife remain largely unexplored. In Australia, remnant woodlands are often dominated by aggressive honeyeaters, especially the noisy miner (Manorina melanocephala). Harassment of smaller birds by miners may result in their exclusion from suitable woodland habitat. We tested whether the presence of noisy miners is also associated with elevated stress in a model species of small passerine bird, the superb fairy‐wren (Malurus cyaneus). We sampled wrens from six sites, three remnant woodlands with noisy miners and three larger fragments of reserved habitat without noisy miners. Differential white blood cell counts were used to infer levels of chronic stress. We also assessed variation in body condition and the prevalence of blood parasites (Haemoproteus spp.) to test for associations between stress and parasitemia. The mean heterophil‐to‐lymphocyte (H:L) ratio was 1.8 × higher among superb fairy‐wrens living in miner‐dominated woodlands, suggesting higher levels of chronic stress. Individuals with higher stress appeared to be in poorer condition, as indicated by fat scores and residual body mass. Prevalence of blood parasites was generally high and was highest in reserved habitat (59%) where miners were absent. Birds with blood parasites living in these habitats had higher H:L ratios but the intensity of infection and H:L ratio was inversely related. Our results suggest that birds persisting in the presence of noisy miners might experience chronic stress, but further study is necessary to separate the relative importance of noisy miner aggression from other potential stressors in small patches of degraded woodland. Stress induced by interspecific aggression should be considered in future studies of wildlife living in remnant vegetation.

Overabundant native animals cause a variety of human-wildlife conflicts that can require management to reduce their social, environmental, or economic impacts. Culling is an intuitively attractive management response to overabundance, but poor monitoring of results and costs means that evidence for successful outcomes is often lacking. Furthermore, many culls worldwide have been ineffective or counterproductive due to ecological release mechanisms or compensatory responses by the overabundant species. We completed a controlled, replicated, costed, and rigorously monitored experimental cull of the endemic Australian honeyeater, the Noisy Miner (Manorina melanocephala). Aggressive exclusion of birds from remnant woodland patches by overabundant Noisy Miners is listed as a Key Threatening Process under Australian conservation legislation due to its impacts on threatened birds. The problem is particularly prevalent in the highly modified agricultural landscapes of eastern Australia. The species impacts avian assemblages at low densities (0.6-0.8 birds/ha) and at a subcontinental scale (>1 million km2 ). Some ecologists recommend culling as the only management response capable of timely reversal of declines of threatened small woodland birds. We monitored Noisy Miner abundance before and for 12 months after a culling program and found that immediate recolonization from the surrounding landscape negated the impact of the cull. We hypothesize that this is due to a vacuum effect; whereby, birds resident in more marginal habitat around treatment patches move into the vacant territory post-cull. Modeled mean abundance of Noisy Miners declined by 22% in treatment sites compared to an increase of 4% in control sites in the post-cull period. Abundance in all sites, however, remained three to five times higher than published ecological impact thresholds. Return on investment analysis indicated no relationship between culling effort and reduction in Noisy Miner abundance. We conclude that culling at a patch scale is not an efficient method of reducing Noisy Miner abundance to levels unlikely to impact threatened woodland birds in the highly modified study landscape, despite estimated costs 18 times lower than another potential management response of revegetation. Our study highlights the importance of building empirical evidence before intuitively attractive but not necessarily ecologically effective management responses are applied more widely.

The effects of habitat fragmentation as a threat to biodiversity are well known; decreased connectivity can potentially influence population processes and dynamics, resulting in smaller, isolated populations that may not function optimally. However, fragmentation may also increase the amount of edge or ecotone habitat available to open country species, benefiting their populations and enabling them to dominate remnant habitats. Noisy miners (Manorina melanocephala) are one such species, occupying eastern-Australian eucalypt woodlands. They are considered a ‘despotic’ species, in that their presence negatively impacts woodland avifauna biodiversity due to their aggressive exclusion of other taxa from occupied areas. Despite this well-known impact, little information exists on the patterns of nest-tree occupancy by noisy miners within eucalypt woodlands. In the current study, we explored the patterns of nest-tree occupancy by noisy miners across two successive years, aiming to identify preferences for breeding areas relative to vegetation structure. Our results show that both habitat fragmentation and the characteristics of individual eucalypt trees in an area influenced nest-tree occupancy. Noisy miners constructed nests in trees near the edge of woodland patches more often than expected. Moreover, the nest tree chosen was a eucalypt that was significantly smaller than randomly selected trees from the surrounding area. The results highlight the importance of habitat management measures that may reduce the suitability of woodland patches as nesting sites for this species, in order to mitigate the severe effects of this despotic edge specialist.

Aim To provide, through a large-scale long-term field study, an empirical evaluation of the extent to which revegetated patches act as refuges for woodland bird species in the face of enhanced abundance of a native despotic species in a highly fragmented landscape. Location South-west slopes, New South Wales, Australia. Methods Birds were surveyed using point counts over a 9-year period. Colonization/extinction dynamics of local bird populations were modelled using multiple-season occupancy models. Results We show how the spread of the noisy miner (Manorina melanocephala), an indirect effect of habitat loss and fragmentation, is now the main driver of bird distribution patterns, affecting 65% of the studied species, including 10 species of conservation concern. Noisy miners both increased the risk that birds would become extinct in patches and prevented birds colonizing new patches. We discovered that restoration plantings, despite having low noisy miner abundance, rarely acted as a refuge for bird species: only 6 of 42 species, and only one of conservation concern, showed a positive response to plantings. Instead, bird species colonized or persisted more in regrowth or old growth sites where the abundance of the noisy miner was relatively low. Main conclusions Despite a major restoration effort of replanted vegetation over several decades, the majority of our target bird species preferred native woodland patches over plantings, and particularly native patches with a low abundance of the noisy miner. Our study showed that conservation actions such as habitat restoration aimed at reversing the effects of habitat loss and fragmentation should be preceded by a careful threat-mitigation prioritization considering, in particular, the indirect effects of fragmentation, such as the impact of despotic or invasive species. Our results support calls to manage noisy miners by undertaking actions that will reduce their numbers, such as through culling.

Aim Strongly interacting species have disproportionately large ecological effects relative to their abundances or biomass. We previously developed two conceptual models that described how one such strong interactor, the Australian bird the noisy miner Manorina melanocephala : (1) establishes resident high-density and hyperaggressive colonies and (2) in doing so, affects other biota and ecosystem processes. Here, we evaluate parts of those models relating to noisy miner habitat preferences and effects on bird assemblages using data from across the geographical range of the miner. Location Eastern Australia. Methods Avian-assemblage data were compiled for 2 128 survey transects (distributed over > 1.3 × 10 6 km 2 ) and were linked to variables reflecting productivity, local habitat structure and landscape context. Predictors were chosen based on the models, although detailed data for some variables were unavailable at such large scales. We used hierarchical Bayesian models that included observation models to account for different survey effort coupled with potentially nonlinear, spatially-explicit process models. Conclusions Noisy miner densities increased with proximity to forest edges (higher densities on forest edges and open sites), in low rainfall areas, and in vegetation dominated by trees with blade-shaped rather than needle-shaped leaves. The presence of noisy miners at even relatively small densities (> 0.6 individuals ha −1 ) depressed both species richness and the abundances of smaller ( 63 g) bird species. In areas with higher mean rainfall, the associations between noisy miners and small- and large-bird species were more negative and less positive, respectively.

Bell miners (Manorina melanophrys; Meliphagidae) are a highly social and very aggressive honeyeater. They are despotic and cooperate in the defence of their territories against other bird species, leading to the almost complete exclusion of other avifauna from miner-occupied regions. This study aimed to resolve some of the fine-scale effects of bell miner aggression on avian diversity both within and adjacent to colonies to determine the true impact of a colony on local avifaunal abundance. Three areas, distributed throughout the range of the bell miner, were surveyed across both non-breeding and breeding seasons to assess the temporal and spatial impacts of bell miner aggression on other bird species. Bell miner colonies were found to occupy very clearly defined areas and had the expected negative impact on avian diversity within their colony. The effects of bell miner colony presence on abundance and richness of avian species were found to cease at the colony boundary, with both recovering to normal levels immediately outside the bell miner colony. Whether bell miners were breeding or not, and irrespective of the amount of vegetation coverage, bell miner colonies were found to have relatively marginal impacts on avian richness and abundance. No impact of colony presence/absence was found on the richness or abundance of the avian species that dwell in the undergrowth, with some evidence that these species were actually more common at the colony edge. Our results demonstrate that the influence of bell miner colony presence upon avian biodiversity is restricted to the confines of the colony and does not radiate outwards into the surrounding habitat. Colony presence influences, therefore, have implications when considering the impact of bell miner behaviour on the diversity of insectivorous birds and processes, most notably the propagation of Bell Miner Associated Dieback.

Anthropogenic activities often cause specialized and fragmentation-sensitive species to be replaced by competitive commensal or invasive species, resulting in reduced diversity and biotic homogenization. However, biotic homogenization driven by increased dominance of a native species has rarely been investigated. Increased abundance of competitive species can have important consequences for assemblage dynamics including homogenization of foraging strategies and, potentially, ecological services. This study assesses how changes to bird assemblages due to the occurrence of an aggressive honeyeater alter the foraging profiles of avifauna in 400 woodland sites in nine study regions across eastern Australia, and explores the potential implications for ecological services. We compared beta diversity among sites with a high and low abundance of the aggressive Noisy Miner Manorina melanocephala. Shifts in ecological characteristics of bird assemblages of sites with high and low abundance of Noisy Miners, including mean and variation in niche position, bill length and body size, were explored. Sites with a high abundance of Noisy Miners were more taxonomically and ecologically homogeneous and had fewer species than sites with a low abundance of Noisy Miners. The mean niche positions of bird assemblages changed and were increasingly dominated by larger vertebrate feeders, granivores and frugivores as Noisy Miner abundance increased. The mean body size and bill length of the insectivore species present at a site increased with Noisy Miner abundance. This change in the bird community along with reduced diversity in foraging strategies implies a loss of the ecological functions provided by smaller-bodied species, potentially affecting plant dispersal and regeneration, insect herbivory and ultimately woodland resilience. Our study demonstrates a substantial shift in ecological profile over a broad geographical area as a result of a single native species.

AimReports of profound changes in species assemblages brought about by the influence of strongly interacting species are increasingly common. Where these strong interactors are sensitive to anthropogenic habitat changes, relatively small alterations in the environment can result in large and pervasive shifts in assemblages. We review the evidence for widespread assemblage-level phase shifts across eastern Australia, triggered partly by anthropogenic habitat alteration and mediated by a native, despotic bird: the noisy miner Manorina melanocephala.

Many passerine bird populations, particularly those that have open-cup nests, are in decline in agricultural landscapes. Current theory suggests that an increase in habitat generalist predators in response to landscape change is partially responsible for these declines. However, empirical tests have failed to reach a consensus on how and through what mechanisms landscape change affects nest predation. We tested one hypothesis, the Additive Predation Model, with an artificial nest experiment in fragmented landscapes in southern Queensland, Australia. We employed structural equation modelling of the influence of the relative density of woodland and habitat generalist predators and landscape features at the nest, site, patch and landscape scales on the probability of nest predation. We found little support for the Additive Predation Model, with no significant influence of the density of woodland predators on the probability of nest predation, although landscape features at different spatial scales were important. Within woodlands fragmented by agriculture in eastern Australia, the presence of noisy miner colonies appears to influence ecological processes important for nest predation such that the Additive Predation Model does not hold. In the absence of colonies of the aggressive native bird, the noisy miner, the influence of woodland predators on the risk of artificial nest predation was low compared with that of habitat generalist predators. Outside noisy miner colonies, we found significant edge effects with greater predation rates for artificial nests within woodland patches located closer to the agricultural matrix. Furthermore, the density of habitat generalist predators increased with the extent of irrigated land-use, suggesting that in the absence of noisy miner colonies, nest predation increases with land-use intensity at the landscape scale.

Overabundant native species can have a significant cascading effect on other components of wildlife, and those that deplete other species, often promoted by anthropogenic change to vegetation cover and habitat, are called reverse keystone species. Birds in the genus Manorina are widely reported as being such species, and in highly disturbed or fragmented environments, and some intact environments, noisy miners Manorina melanocephala can have a strong negative effect on small passerine species via hyper-aggressive mobbing. The tropical savannas of northern Australia consist of largely unmodified woodlands, and two species of Manorina occur naturally in this region: the noisy miner and the yellow-throated miner Manorina flavigula. Therefore, what effect do these species have on bird assemblage in predominantly continuous habitats, relative to other typical determinants of avifauna assemblage such as vegetation structure? We used data collected from bird surveys at 511 sites across northern Queensland (179 noisy miner M. melanocephala sites, 332 yellow-throated miner M. flavigula sites) between 1998 and 2010. We examined the variation in bird composition at each site due to increasing abundance of Manorina spp. using uni- and multivariate techniques. We found total bird richness was significantly lower in sites where noisy and yellow-throated miner abundances were highest, and passerine species seemed most affected. For species, 45 species varied significantly in abundance with increasing miner numbers, and the overall effect of yellow-throated miners on other birds seemed more pronounced. However, vegetation structure was generally an equal or more important predictor of avifauna richness and abundance. We conclude that despite the superficially intact nature of northern Australian woodlands, pastoral intensification or poor land management might create disturbances that facilitate increases in the abundance of Manorina, causing localized overabundance and a compounding negative effect on other native bird species.

Urbanization 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.

Alarm calls are vocalisations animals give in response to predators which mainly function to alert conspecifics of danger. Studies show that numerous species eavesdrop on heterospecific calls to gain information about predator presence. Responding to heterospecific calls may be a learned or innate response, determined by whether the response occurs with or without prior exposure to the call. In this study, we investigated the presence of eavesdropping behaviour in zebra finches Taeniopygia guttata. This species is not known to possess a distinct alarm call to warn adult conspecifics of a threat, and could be relying on alarm calls of nearby heterospecifics for predator information. We used a playback experiment to expose captive zebra finches to three heterospecific sounds: an unfamiliar alarm call (from the chestnut‐rumped thornbill Acanthiza uropygialis), a familiar alarm call, and a familiar control (both from the noisy miner Manorina melanocephala). These calls were chosen to test if the birds had learnt to distinguish between the function of the two familiar calls, and if the acoustic properties of the unfamiliar alarm indicated presence of a threat to the finches. Our results showed that in response to the thornbill alarm, the birds reduced the rate of production of short calls. However, this decrease was also seen when considering both short and distance calls in response to the control sound. An increase in latency to call was also seen after the control stimulus when compared to the miner alarm. The time spent scanning increased in response to all three stimuli, but this did not differ between stimuli. There were no significant differences when considering the stimulus by time interaction for any of the three vigilance measures. Overall, no strong evidence was found to indicate that the captive zebra finches were responding to the heterospecific alarm stimuli with anti‐predator behaviour.

Investigated displays of Noisy Miners, Manorina melanocephala, in Australia. This unusual bird lives in colonies and many male male care for the offspring of each female. 3 flight displays, 11 non-flight displays, and several components of facial displays (including a variable eye patch) are discribed. The eye patch provides a large yellow and black augmented eye, important in intimidation. No stereotyped sequence of courtship behaviour precedes copulation. Displays are used to advertise nest locations. A greeting display, the corroboree, is extremely common. The possibility of the evolution of submissive display from threat is discussed. Special vocalisations of male male and female female are used in a duet. The maintenance of bonds among many individuals in a colony may be more important than strong pair bonds. Group cohesion is probably maintained by flight display, nest display, mobbing, and other communal activities. High interspecific aggression results in few resident species in colonies. This level of interspecific aggression might be maintained by incorporating much intraspecific mimetic display and ritualised submissive behaviour.

Tree 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.

Individual differentiation is usually advantageous in maximising the fitness benefits of interactions with conspecifics. In social species, where intraspecific interactions are frequent, this is likely to be particularly important. Indeed, some form of differentiation underpins most hypotheses proposed to account for cooperative behaviour in birds. The auditory modality is a likely candidate for this function, particularly for species where individuals are widely spaced and in dense vegetation. In this study, we examined the acoustic structure of a distinctive mobbing signal, the ‘chur’ call, of the cooperatively breeding noisy miner Manorina melanocephala. Using 250 calls from 25 individuals, a combination of spectrographic-based measurement of call parameters, cross-correlation and multi-dimensional scaling was used to test for systematic individual differences in call structure. Strong differences between individuals were observed in all measures, indicating that this call encodes sufficient information to facilitate individual differentiation. We then conducted a series of field playbacks to test the effect of the behaviour on conspecifics. Results demonstrated that the call, in isolation, has a clear attractant effect. Given that chur calls are synonymous with the characteristic cooperative mobbing behaviour of this species, these findings suggest they are likely to have an important function in coordinating complex social behaviour.

The 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.

This 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.

The Noisy Miner is a communally breeding Australian honeyeater in which several males feed the offspring of a single female. They reside year‐round in colonies, which may number several hundred birds. Miners within colonies unite to mob predators and are successful in defending their colony area against all other species of birds. The species is also highly aggressive intraspecifically. Individuals in a colony in southeastern Queensland were present most of the time in small activity spaces. Most resident males showed extensive overlap of activity space from one season to the next. Males did not defend their activity spaces, so that coalitions of birds occurred whose membership changed with place and time. Certain assemblages of males, termed coteries, were of a more permanent nature. Coterie members showed aggression towards outsiders at border regions. Females' activity spaces were much smaller and less variable than those of males. They showed almost no overlap and were probably maintained by mutual avoidance. Females tended to nest within the activity space they occupied shortly before the breeding period. Thus the spacing of males and females within a colony was quite different. Interactions, often agonistic, were frequent between individuals, between an individual and a group, and between groups. Encounters involving two males in which participants normally lived farther apart were more often agonistic than when participants lived more closely, and more aggression was seen within coteries than between them. When larger groups of birds had agonistic encounters, they more frequently involved birds from different coteries. Very little male‐female aggression was seen. Interactions between males and females of different coteries were usually sexual, sometimes involving attempted copulation. Colony sizes are probably too large to permit individual recognition of fellow members, but this could be more likely in coteries. Many males in coteries are doubtless closely related, but outsiders frequently infiltrate them. Coteries are not reproductive units. Copyright

Summary Noisy Miners (Manorina melanocephala) are aggressive Australian honeyeaters that dominate many areas of remnant vegetation and forest edges from which they competitively exclude small birds. A similar domination can also occur in planted wildlife corridors. The aim of this study was to determine which corridor plantings encouraged the presence of small native birds in regions where Noisy Miners dominate. Six vegetation mixes were investigated in the main study: eucalypts with and without shrubby understorey; acacia with and without shrubby understorey; exotic conifer; and exotic deciduous trees. A supplementary study then examined sites with a mixture of eucalypt and acacia trees with a shrubby understorey. The findings showed that Noisy Miners dominated corridors of eucalypts, virtually excluding small birds, whereas native acacias, exotic conifer and exotic deciduous corridors had small birds and no resident Noisy Miners. The greatest abundance and richness of small birds occurred in plantings combining eucalypts with at least 15% acacias, in this case bipinnate species. Given these results, it is recommended that eucalypt plantings should be supplemented with both acacias (preferably bipinnate) and a shrubby understorey.

Aim: To determine the factors influencing the distribution of birds in remnants in a fragmented agricultural landscape. Location Forty-seven eucalypt remnants and six sites in continuous forest in the subhumid Midlands region of Tasmania, Australia. Methods: Sites were censused over a two-year period, and environmental data were collected for remnants. The avifauna of the sites was classified and ordinated. The abundances of bird species, and bird species composition, richness, abundance and diversity were related to environmental variables, using simple correlation and modelling. Results: There were two distinct groups of sample sites, which sharply differed in species composition, richness, diversity and bird abundance, separated on the presence/absence of noisy miner (Manorina melanocephala Latham) colonies, remnant size, vegetation structural attributes and variables that reflected disturbance history. The approximate remnant size threshold for the change from one group to another was 20–30 ha. Remnant species richness and diversity were most strongly explained by remnant area and noisy miner abundance, with contributions from structural and isolation attributes in the second case. Segment richness was explained by precipitation, logging history and noisy miner abundance. Bird abundance was positively related to precipitation and negatively related to tree dieback. The 28 individual bird species models were highly individualistic, with vegetation structural variables, noisy miner abundance, climatic variables, variables related to isolation, area, variables related to floristics, disturbance variables, the nature of the matrix and remnant shape all being components in declining order of incidence. Age of the remnant did not relate to any of the dependent variables. Main conclusions: Degraded and small remnants may have become more distinct in their avifaunal characteristics than might otherwise be the case, as a result of the establishment of colonies of an aggressive native bird, the noisy miner. The area, isolation and shape of remnants directly relate to the abundance of relatively few species, compared to vegetation attributes, climate and the abundance of the noisy miner. The nature of the matrix is important in the response of some species to fragmentation.

We quantitatively assessed edge effects associated with elevated abundance of a hyper aggressive bird species, the noisy miner Manorina melanocephala, in fragmented eucalypt forest adjoining developed land. Long-term data from Toohey Forest, subtropical Australia, show that noisy miner colonies intensively occupy a zone of 20 m from the forest edge, with frequent use occurring up to 100 m from the edge, but little beyond 200 m. Within noisy miner colonies, the abundance and species richness of other birds were both about half those recorded at nearby transects which were outside the colonies' main activity area. Bird species smaller than noisy miners, which are also those with similar diets, were collectively 20–25 times more abundant, and their species richness tenfold greater, outside miner colonies than within them, whereas larger species, which have less dietary overlap, did not differ. Exclusion of small insectivorous birds has been hypothesised to cause elevated insect herbivore density, but we found no difference between tree crown defoliation or dieback rates within versus outside miner colonies. Aggression by noisy miners can be viewed as a mechanism of interspecific competition, since miners have a relatively large body size for their diet and are hence able to exclude virtually all potential competitors at relatively little cost. We examine evidence indicating that reduced bird diversity in eucalypt forest fragments of eastern Australia is often simply the effect of noisy miner occupancy of edges, acting directly on the densities of other species through their aggressive behaviour. With an edge effect 200 m deep, a remnant 10 ha in size is likely to become entirely occupied by noisy miners, and this is a size threshold that has been commonly reported in association with area-standardised avian diversity reductions. Convergent patterns of species loss from small forest fragments in different continents are the result of different underlying ecological processes.

Aim Animal assemblages in fragmented landscapes are likely to be determined by contemporary (e.g. patch size, biotic interactions) and historical (e.g. change in patch area) characteristics of patches and their positioning in the landscape (e.g. connectivity). We considered the influence of habitat structure, landscape context, history and an aggressive, native bird species [the Noisy Miner Manorina melanocephala (Latham 1801)] on three characteristics of woodland-dependent bird assemblages in a fragmented, eucalypt-forest landscape. The response variables were: (1) species richness (SR), (2) sums-of-densities (i.e. total number of individual birds), and (3) occurrence of rare species [through a rare-species index (RSI)]. Location Box-ironbark, eucalypt forests of central Victoria, Australia (broadly bounded by: 36–37° S, 142–146° E). Methods There were replicates of four size-classes of fragments (10, 20, 40, 80 ha) and replicates of the same size-classes set within large blocks of extant forest. This design allowed us to distinguish between area-specific and fragmentation effects by comparing same-sized fragments and reference areas to establish fragmentation-specific impacts. Results Species richness was less than expected in smaller fragments and this was apparently because of current fragment area, density of the Noisy Miner and habitat quality. The RSI exhibited similar dependencies, while sums-of-densities appeared to be related to the number and quality of wooded linkages to fragments. The historical variable was forested–area change of each fragment between 1963 and 1996, and was found to have no relationship to any of the response variables. Main conclusions The lack of historical influence suggested that the avifaunas of the fragments are unlikely to be `relaxing' from isolation effects through local extinctions, but are more likely to be dominated by dynamic recolonization and abandonment both seasonally and among years. The dependence of sums-of-densities on the linkage variable appeared to be largely because of the responses of two species, the Red Wattlebird Anthochaera curunculata (Shaw, 1790) and the Yellow-tufted Honeyeater Lichenostomus melanops (Latham, 1801). These species are among the three most common in the large forest blocks, but are much rarer in fragments. The connectedness effect suggests that these species may depend upon linkages to occupy fragments that are only moderately distant from large forested areas within this region.

Cooperatively breeding noisy miners (Manor ina melanocephala) are well known in Australia for their persistent and very vocal group mobbing of heterospecifics. Here I investigated the nature of this extraordinary behaviour, in particular its role in nest defence, in a colour banded population of noisy miners in south-east Queensland, Australia. I focused on two questions. First, did the intensity of mobbing vary according to factors such as the threat to the nest, or the 'value' of a clutch? Secondly, what role did group mobbing play in the success of a nest? To answer these questions, I experimentally manipulated the nest defence behaviour by placing one of three stuffed models near active noisy miner nests. The response of noisy miners to intruders was not indiscriminate. However, I found that the number of birds that mobbed a model did not simply reflect the potential threat posed. The response of noisy miners to raptors and other potential nest predators may have reflected their rarity as well as the threat posed. The number of mobbers did not vary with the age or size of a brood. In this study, the fate of nests was independent of the number of mobbers or visitors at nests. Finally, up to 80% of mobbers were never seen to make any other type of contribution to a nest, and many could not be related to the brood that they were 'defending'. Hence, for some noisy miner 'helpers' the benefits that they accrued were probably not wholly dependent on the survival of the broods. I suggest that, in this gregarious species, mobbing behaviour at the nest may be a display of social status or individual quality. This hypothesis warrants further investigation.