Abstract Context Land-use change associated with urbanization is a global conservation issue. Urbanization alters the composition of biotic assemblages through the loss, gain and replacement of species; and has the potential to homogenize biotic communities within cities. An important challenge for conservation in urban environments is to identify and respond to the factors that influence compositional change, particularly at the landscape-scale. Objectives We aimed to: i) identify properties of residential landscapes that shape avian community composition; ii) test for evidence of homogenization at the landscape-scale; and iii) determine the relative influence of species loss and species turnover in the homogenization of native bird communities. Methods We surveyed birds in 30 residential landscapes (each 100 ha), stratified to represent gradients of housing cover (from 9–39%) and canopy tree cover (13–63%) in Melbourne, Australia. Results The composition of bird communities, and the relative abundance and richness of foraging guilds, showed marked variation across urbanizing landscapes, most strongly associated with housing cover, vegetation patterns, and relative abundance of an aggressive competitor, the noisy miner ( Manorina melanocephala ). There was strong evidence for homogenization of native bird communities in landscapes with high housing cover, driven primarily by differential loss of forest-dependent species. Conclusions Actions to counter biotic homogenization and retain forest-dependent bird species include maintaining large areas of (semi)natural vegetation among, and adjacent to, residential areas; and revegetating open green spaces to include native understorey cover. Enhancing education for residents about the habitat requirements of forest-dependent species is also an important step in conserving native avifauna.

ABSTRACTCats (Felis catus) kill millions of native Australian mammals and birds each year. The prey naivety hypothesis suggests this is due to native wildlife failing to recognise cats as predators. The Mata Hari Judas (MHJ) queen technique, where confined female cats are put into prolonged oestrus, has recently been trialled in situ as a method to attract and capture feral cats. This created the opportunity to observe how native wildlife respond to a live cat, or their olfactory and auditory cues, using camera trap detections before and after the introduction of a MHJ queen or its cues. Daily detection rates of eastern grey kangaroos, Australian magpies, noisy miners and northern brown bandicoots around the live cat did not differ between baseline and live cat periods, suggesting these species may not recognise live cats as a threat. However, red‐necked wallabies and grey butcherbirds reduced activity in response to live cats or their cues. This study demonstrates that native Australian wildlife exhibit variable behavioural responses to cats and their cues. As predator control strategies evolve, integrating behavioural ecology into their design will be critical for their effectiveness, such as prioritising species that lack predator awareness.

Abstract While habitat fragmentation negatively impacts native biodiversity, this ecological process can generally be beneficial for edge‐specialist species that preferentially occupy remnant patches. In the woodlands of eastern Australia, this process leads to domination of remnant patches by a despotic native honeyeater, the noisy miner (Manorina Melanocephala), resulting in aggressive exclusion of other avifauna. Culling has been trialled to alleviate the impacts of noisy miners, but has yielded only mixed success in the short term as recolonising miners from the surrounding areas often occupy newly culled sites. We tested if continuous removal of Noisy Miners could create an artificial ‘sink’ habitat that would continually attract dispersing Noisy Miners to preferentially colonise the ‘sink’ area, reducing miner dispersal into other areas in the landscape and allowing recovery of native woodland birds as a result. Over an 18‐month period, Noisy Miners were regularly removed from two colonies, and the resulting changes in both miner density and the diversity of other woodland birds were evaluated. At one colony, Noisy Miners routinely recolonised the area after each removal, creating an artificial ‘sink’ habitat as miner density rapidly recovered in between culling rounds. However, by attracting dispersing miners in the landscape to this culling site, it follows that recolonisation pressure elsewhere would have fallen. This was evident in this study through a nearby area failing to be recolonised by miners post‐culling for more than 1 year, and also concurrently experiencing an improvement in avian diversity in the absence of miners. This shift in diversity away from the sink site highlights the potential of this technique to deliver broad‐scale results with relatively quick outcomes. Furthermore, the simplified protocol of repeated culls undertaken at a sink site is likely to be both logistically simpler and cheaper for land managers than attempting culling across all areas occupied by miners. Practical Implication. Continuous removal of Noisy Miners at designated ‘sink’ sites can attract dispersing individuals, reducing recolonisation elsewhere and promoting native woodland bird recovery. This cost‐effective approach is simpler than widespread culling and minimises landscape disruption. Ongoing culling at favoured sites is likely more effective than short‐term efforts across multiple locations, providing a practical strategy for managing native species exceeding ecological carrying capacity.

Glucocorticoid (GC) hormones regulate the vertebrate stress response and are secreted by the hypothalamic-pituitary-adrenal (HPA) axis. Acute elevation of GCs is thought be adaptive because it promotes physiological and behavioural changes that allow animals to cope with disturbances. In contrast, chronic elevation of GCs is associated with reduced body condition, immune function, reproductive success, and survival. In adult birds, the effects of chronic stress have been well documented, including human-related disturbances. In contrast, the effects of chronic stress on nestlings have rarely been addressed. This is of interest, as many ecological or monitoring studies of wild birds require nestlings to be regularly handled. However, the consequences of repeated handling of nestlings on HPA axis function and body mass in wild birds remain poorly quantified. We examined whether daily exposure to handling stress increased corticosterone (the dominant avian glucocorticoid) secretion and reduced pre-fledging body mass relative to undisturbed control nestlings of the noisy miner (Manorina melanocephala), a native Australian passerine bird. Daily handling resulted in an elevated baseline and attenuated stress-induced corticosterone levels in disturbed 14-day nestlings, in comparison with control nestlings handled for the first time. Despite this, disturbed and control nestlings fledged at a similar body mass. Baseline and stress-induced corticosterone increased with nestling age but remained independent of nestling sex and hatching order. Our findings are some of the first to suggest that chronic handling stress causes physiological alterations to the development of the HPA axis in nestling birds, and our data suggest that researchers should minimise or account for handling stress in their experiments. These data also raise the possibility that other chronic stressors may have long term physiological consequences for the development of the HPA axis in nestling birds.

Abstract The regent honeyeater Anthochaera phrygia is a Critically Endangered Australian songbird, with current population estimates of < 300 individuals remaining in the wild. Low nest success is a factor preventing the recovery of the population, and management remedies are needed. However, a lack of data on intervention success raises uncertainty and impedes planning. To identify management priorities under uncertainty, we engaged with conservation practitioners and key stakeholders to develop and evaluate potential nest protection interventions. Four categories of threats were considered: avian predators, mammalian predators, extreme weather events and avian competitors. The interventions with the highest predicted probabilities of nest success under each threat category were, respectively: lethal control of avian predators, the use of tree collars to control arboreal mammalian predators, the provisioning of supplementary food and nesting resources during extreme weather events, and control of the noisy miner Manorina melanocephala, a competitor species. Our analysis shows that by applying a combination of conservation actions alongside improvements in nest detection, it is possible, based on the opinion of experts, to provide a pathway for the recovery of the regent honeyeater.

ABSTRACT The Noisy Miner (Manorina melanocephala) is a native Australian honeyeater that reduces avian biodiversity at sites it occupies through aggressive defence. Culling to remove miners has had limited success in some areas due to rapid recolonisation. This experiment trialled ‘doughnut culls’ as a new approach to reduce Noisy Miner aggression within a central area of colonies, by removing up to half the miners present within a 50 m radius of an identified central location in 29 different colonies on the New England Tablelands of NSW. Aggression from miners onsite within this central area was quantified before and after culling by presenting 3D printed models of three different bird species with accompanying vocal playback to resident miners at the centre of culled areas. These presentations identified a significant decline in Noisy Miner aggression onsite after doughnut culls, with this reduced rate of aggression (e.g. over 50% reduction in the maximum number of miners within a 20 m radius of models) remaining until the conclusion of the experiment at 28 days post culling, a timeframe commensurate with the duration of many passerine nesting attempts. Social hierarchy changes among remaining Noisy Miners may be the primary cause of this reduced aggression, with sufficient miners remaining onsite to prevent colony collapse and thus any recolonisation. While additional trials during peak Noisy Miner dispersal periods are warranted, this method provides an effective tool for land managers to reduce localised Noisy Miner aggression over the short to medium term when high conservation areas are identified.

Impact of a ‘reverse keystone species’ on the temporal dynamics of bird communities in Australia

Mobbing is a widespread, vocally coordinated behaviour where species approach and harass a threat. The noisy miner (Manorina melanocephala) is a notorious native Australian honeyeater, well‐known for its hyperaggressive mobbing. Numerous studies have identified negative impacts of their mobbing behaviour, highlighting the exclusion of competitors from colony areas and the resulting loss of woodland‐bird biodiversity. Despite this, few studies have investigated mobbing itself, and our understanding of the factors which influence its expression remains limited. Here, we use a field‐based playback experiment to investigate whether mobbing responses vary in relation to colony borders and caller familiarity. Noisy miners were more likely to respond, reacted more quickly and responded more strongly to mobbing calls broadcast inside as opposed to outside the colony. These behavioural differences likely arise from variation in the relative costs and benefits of responding. When noisy miners did mob outside the colony, more individuals joined in response to unfamiliar as opposed to familiar callers. Our results reveal that noisy miner mobbing may not be as indiscriminate as often assumed, with caller familiarity and location influencing this behaviour. We suggest there are benefits to greater consideration of the factors impacting noisy miner mobbing behaviour.Keywords: Avian biodiversity, interspecific aggression, mobbing behaviour, noisy miner, vocal communication

The decline of birds in farmland is a conservation and land-management issue of global concern. Linear woodland corridors along roadsides in Australian farmland can play an important network role, maintaining ecological connectivity at the landscape scale and thereby supporting the survival of disturbance-sensitive woodland species. This paper presents a case study investigating the connectivity value of Old Narrandera Road, an old (pre-1870) roadside woodland corridor linking three larger woodland remnants near Wagga Wagga, in southern inland New South Wales, Australia. A survey of 120 plots along this corridor during 2018–2019 identified 81 bird species including 25 declining woodland birds of known conservation concern. Presence of the hyper-aggressive Noisy Miner Manorina melanocephala in survey plots was negatively correlated with total species richness and declining woodland bird assemblage richness and several species (predominantly small to medium-sized declining woodland birds rather than common farmland birds) exhibited a degree of spatial separation with Noisy Miners. One decliner, Grey-crowned Babbler Pomatostomus temporalis, showed a significant positive association with Noisy Miner, potentially reflecting a greater tolerance to harassment by Miners. Although the Noisy Miner is probably limiting realisation of the connectivity value of this woodland corridor at present, corridors as substantial and significant as Old Narrandera Road are scarce in the local landscape, and the woodland complex of three interconnected remnants it brings together is likely to be important for the local conservation of many declining woodland bird species.

Aposematic prey advertise their unprofitability with conspicuous warning signals that are often composed of multiple color patterns. Many species show intraspecific variation in these patterns even though selection is expected to favor invariable warning signals that enhance predator learning. However, if predators acquire avoidance to specific signal components, this might relax selection on other aposematic traits and explain variability. Here, we investigated this idea in the aposematic moth Amata nigriceps that has conspicuous black and orange coloration. The size of the orange spots in the wings is highly variable between individuals, whereas the number and width of orange abdominal stripes remains consistent. We produced artificial moths that varied in the proportion of orange in the wings or the presence of abdominal stripes. We presented these to a natural avian predator, the noisy miner (Manorina melanocephala), and recorded how different warning signal components influenced their attack decisions. When moth models had orange stripes on the abdomen, birds did not discriminate between different wing signals. However, when the stripes on the abdomen were removed, birds chose the model with smaller wing spots. In addition, we found that birds were more likely to attack moths with a smaller number of abdominal stripes. Together, our results suggest that bird predators primarily pay attention to the abdominal stripes of A. nigriceps, and this could relax selection on wing coloration. Our study highlights the importance of considering individual warning signal components if we are to understand how predation shapes selection on prey warning coloration.

Abstract AimAustralian woodlands have been intensively cleared since European settlement and, in parallel, many species of birds inhabiting this habitat type have experienced a marked decline. Conversely, some species such as noisy miner Manorina melanocephala respond positively to habitat disturbance and due to their hyper‐aggressiveness can end up driving away specialized and fragmentation‐sensitive species. Recent studies have suggested that the negative impact of miners is exacerbated by means of synergistic interactions between these and other aggressive species, including nest predators. However, it is not clear if these positive associations arise through similar habitat requirements or due to potential mutual benefits (‘facilitation effects’), which should predominate in harsh environments as the stress‐gradient hypothesis (SGH) predicts.LocationEastern Australia.MethodsWe combined a multi‐season community N‐mixture model and joint species distribution models within the Hierarchical Modelling of Species Communities framework to examine species co‐occurrence patterns after accounting for imperfect detection and the influence of environmental variables. We then explored how the balance between positive and negative associations varied along an abiotic stress gradient and whether species‐to‐species associations were non‐randomly distributed with respect to species traits.ResultsNo significant associations were detected; we only found tentative associations (posterior probability 85%) in a low proportion of species pairs (~4%). Although most non‐random (tentative) associations were negative, these were weaker and less consistent across models than the positive ones. Five medium‐sized species of swooping birds including the noisy miner monopolized virtually all positive associations. Communities from low‐productivity environments tended to show a lower degree of overall (community‐level) competitiveness than those located in less stressful (more productive) environments, which supports the SGH. There was no significant relationship between species trait dissimilarity and species‐to‐species association's strength.Main ConclusionsOur results suggest that aggressive species like miners, kookaburras, lorikeets, magpies and butcherbirds can form potential synergies with each other that may intensify the direct negative influence of each species on small‐sized songbirds. Since these species thrive in anthropized landscapes and have drastically increased their numbers in some regions, their associative potential should be considered in conservation actions.

Grazing regime effects on bird biodiversity overwhelmed by an interference competitor

Abstract AimMuch research has quantified species responses to human‐modified ecosystems. However, there is limited work on how human‐modified ecosystems may reshape competitive interactions between species. Using a 19‐year study across 3 million ha, we aimed to answer the question: Are levels of interference competition between bird species context dependent and influenced by habitat structure and productivity? We focussed on the hyper‐aggressive behaviour of the Noisy Miner (Manorina melanocephala), which is recognized as a key threatening process for other woodland bird species in Australia. Whether environmental conditions such as amount of forest cover and net primary productivity (NPP) mediate the Noisy Miners' impact remains untested at large spatiotemporal scales.LocationTemperate woodlands of south‐eastern Australia.MethodsWe gathered data on bird site occupancy from repeated surveys of field sites and assembled satellite data on tree cover and NPP. We constructed Bayesian multi‐species occupancy/detection models of bird species in woodland patches and tested the fixed and interactive effects of Noisy Miner presence, the amount of tree cover, NPP, and time. We quantified the responses of 31 species, many with known interactions with the Noisy Miner documented previously at fine spatial scales.ResultsWe identified negative associations between the Noisy Miner and 18 bird species, including, unexpectedly, both small and large bodied taxa. Site occupancy in some species was influenced by interactions between Noisy Miner presence and increasing amounts of tree cover or productivity. For some species, interference competition by the Noisy Miner is context‐dependent and mitigated by increasing tree cover and/or increasing NPP.Main ConclusionsOur analyses revealed that woodland bird conservation in our study region will be promoted by protecting refugia characterized by areas of high NPP and high tree cover. Preventing vegetation clearing that reduces tree cover could reduce interference competition by the Noisy Miner on parts of the remaining woodland bird community, including species of conservation concern.

Habitat destruction and fragmentation increasingly bring humans into close proximity with wildlife, particularly in urban contexts. Animals respond to humans using nuanced anti-predator responses, especially escape, with responses influenced by behavioral and life history traits, the nature of the risk, and aspects of the surrounding environment. Although many studies examine associations between broad-scale habitat characteristics (i.e., habitat type) and escape response, few investigate the influence of fine-scale aspects of the local habitat within which escape occurs. We test the “habitat connectivity hypothesis,” suggesting that given the higher cost of escape within less connected habitats (due to the lack of protective cover), woodland birds should delay escape (tolerate more risk) than when in more connected habitat. We analyze flight-initiation distances (FIDs) of five species of woodland birds in urban Melbourne, south-eastern Australia. A negative effect of habitat connectivity (the proportion of the escape route with shrubs/trees/perchable infrastructure) on distance fled was evident for all study species, suggesting a higher cost of escape associated with lower connectivity. FID did not vary with connectivity at the location at which escape was initiated (four species), apart from a positive effect of habitat connectivity on FID for Noisy Miner Manorina melanocephala. We provide some support for two predictions of the “habitat connectivity hypothesis” in at least some taxa, and conclude it warrants further investigation across a broader range of taxa inhabiting contrasting landscapes. Increasing habitat connectivity within urban landscapes may reduce escape stress experienced by urban birds.

Abstract Addressing threats to biodiversity from pest species is a global challenge. One such challenge is to mitigate the impact of an overabundant Australian songbird, the noisy minerManorina melanocephala,on woodland birds. The overabundance of noisy miners is listed as a key threatening process under federal biodiversity legislation, but current understanding of where and how noisy miner populations can be managed to yield conservation benefits is unclear. We evaluated the effectiveness of noisy miner removal across 12 treatment areas totaling 3913 ha and nine control areas totaling 1487 ha important for the critically endangered regent honeyeaterAnthochaera phrygia. Removal of noisy miners significantly reduced their densities in all but one of the treatment areas. In 10 of the 12 treatment areas, noisy miner densities remained below an impact threshold of 0.65–0.83 birds ha−1for at least 3 to more than 12 months. The percentage of suitable noisy miner habitat in the surrounding landscape was not a strong predictor of noisy miner management success. Regent honeyeaters occupied six treatment areas, nesting successfully in four. The abundance of other songbirds increased post‐miner removal in seven areas, decreased in three, and was mixed in two. Data from the control areas showed some variation in songbird numbers was independent of noisy miner management. We conclude that noisy miners can be managed in areas of high conservation value for a minimum cost of AUD $10 ha−1. Larger treatment areas may be more important than the broader landscape context in maintaining long‐term noisy miner suppression. Standardized, long‐term monitoring is crucial to identify not only the drivers of pest species recolonization but also locations where threats from pests on endangered species can be addressed effectively while minimizing animal welfare and financial costs.

In birds, several physiological characters have been proposed and tested as possible criteria of age. Among them, skull development is likely to provide a valuable reflection of other physiological developments, however the relationship between skull ossification and other physiological and morphometric traits has rarely been quantified within species. Here, we investigated suitability of skull ossification as an indicator of age in Noisy Miners (Manorina melanocephala), an Australian passerine bird. We compared skull ossification with other age indicators including the bursa of Fabricius, gonadal development, and a range of commonly used body size measures that included wing length and tarsus length. We carried out morphological measurements on 1251 individual Noisy Miner carcasses that had been collected during a culling experiment in November, December and May 2015–2016 from north-eastern NSW, Australia. The probability of a bursa of Fabricius being present in an individual bird changed with skull ossification level, with a significant reduction in the size of the bursa of Fabricius correlating with the degree of skull ossification. In male Noisy Miners, birds that were at a later stage of skull ossification had significantly larger testis size than those with a lower stages of skull ossification. In females, ovary size increased significantly as skull ossification progressed. In both sexes, skull ossification level was also correlated with body mass and skeletal measures. Given this, the level of skull ossification in Noisy Miners accurately correlates with other age indicators, and can justifiably be used as a non-invasive aging method in the field for live birds.

Abstract AimsThe effect of spatial scale on the location and abundance of species has long been a major topic of interest in ecology. Accounting for key drivers at multiple scales is critical for rigorous description of patterns of species distribution and biodiversity change. We quantified the effects of potential drivers of bird occupancy across a geographically dispersed, but heavily disturbed and fragmented ecosystem.LocationThreatened Box‐Gum Grassy Woodlands in south‐eastern Australia, which stretch across 9° of latitude (~900 km).TaxonBirds (Class Aves).MethodsWe grouped data from four monitoring studies of birds that spanned 10–22 years in Box‐Gum Grassy Woodlands. We then employed joint species distribution modelling to investigate multi‐species responses to environmental drivers measured at patch, landscape and regional scales, and selected combinations of all three.ResultsWe show that in Box‐Gum Grassy Woodlands: vegetation structure influences bird occupancy beyond the presence of the despotic Noisy Miner (Manorina melanocephala); woodland cover is more important than vegetation productivity and topographic position; bird occupancy is sensitive to a combination of average climate, seasonality, and summer and winter extremes; and there is limited redundancy between drivers of bird occupancy at different scales. Species differ most in their response to presence of the Noisy Miner, high summer temperatures and nearby woodland cover.Main ConclusionsQuantifying the influence of environmental drivers that act at different spatial scales is valuable for understanding patterns of bird species occurrence. Fine‐scale studies can benefit from considering the climate and biogeographical context in which the research occurs. Conversely, large‐scale studies should recognise that downscaling species occupancy projections from continental to patch scales requires careful consideration of the role of patch‐scale vegetation.

ABSTRACT 1878: “…gallant little birds” (Wagga Wagga Advertiser) 1915: “… the carol of the magpie is eclipsed by the song of the miner” (Emu) 2004: “…the mafia of the bird world” (Australian Broadcasting Corporation) 2015: “I hate those f***in things” (RedditAustralia) Through the 19th Century and the first half of the 20th Century, notwithstanding its role as an agricultural pest, the Noisy Miner Manorina melanocephala was considered with affection by colonial society. The species’ reputation has been severely damaged in recent decades, however, on account of its violent tendencies towards smaller woodland birds, including many of conservation concern. Aggressive exclusion of small woodland birds from potential woodland habitat by Noisy Miners was declared a Key Threatening Process under federal conservation legislation in 2014. Given that Noisy Miners, other woodland birds, and the post-ice age woodland environment have been co-evolving for at least 10 000 years, how did the natural competitive behaviour of Noisy Miners become an ecological problem? In this paper I review historical references to Noisy Miners and current research on the ecology of the species to construct a trajectory of change. Culturally, these changes include a shift in attitudes to the species from agricultural pest and popular native bird to a vilified, “overabundant” native species and nemesis of small woodland birds. Ecologically, changes have included an expansion in distribution and abundance of Noisy Miners. This has led to an increase in scale of the effects of Noisy Miner aggression on small woodland birds. The historical record contains many references to Noisy Miner aggression against other species, the first appearing within four years of the arrival of the First Fleet in 1788. Evidence that such aggression could affect the abundance and distribution of small woodland birds, however, appears only in the period after World War II. The changing ecological role of Noisy Miners, and the associated changes in cultural attitude to the species, appear linked to the loss, fragmentation and degradation of native woodland in eastern Australia since the introduction of European agriculture and urbanization. In particular, the change in ecological role of the Noisy Miner appears to be linked to the accelerated rates of deforestation in the post-war period. Such broadscale habitat modification has both benefitted Noisy Miners and exacerbated declines in woodland-dependent small birds.

ABSTRACT The Noisy Miner (Manorina melanocephala) is a cooperative honeyeater living in social groups throughout south-east Australia that displays high levels of interspecific aggression and reduces avifaunal biodiversity in areas it occupies. Human-induced habitat changes have also potentially increased the availability of high-quality habitat and food resources available for Noisy Miners, which may in turn affect activity budgets and the duration or intensity of aggression displayed by Miners towards other species. To quantify the impact of differences in the potential availability of anthropogenic food resources on Noisy Miner aggression levels, we presented taxidermy models from three different categories of bird species (food competitors, non-food competitors and potential predators) and quantified observed aggression in three separate habitats: natural areas with very limited additional anthropogenic food resources, gardens that provided supplementary resources such as nectar-rich ornamental plants, and cafés that provided access to human food items. As predicted, Noisy Miners exhibited agonistic behaviours for a significantly longer period in the habitats with anthropogenic food resources, namely gardens and cafés in comparison to natural areas. The type of model presented also impacted Miner response, with: (1) greater numbers of Miners mobbing predator rather than competitor models, (2) Miners mobbing predator models for longer periods than competitors, and (3) a greater probability of Miners physically contacting competitor models. These findings demonstrate that additional resources have the ability to impact time budgets of species and, for hyperaggressive birds such as Noisy Miners, can impact biodiversity in more nuanced ways than previously quantified.

Context Sex and age are frequently proposed as drivers of a number of behavioural and demographic patterns that can have important consequences for population dynamics including access to mates, sexual selection, parental care and lifetime productivity. Sex and age might also be important in shaping the movement patterns and colonisation processes of social species moving into vacant habitat. Such information is critical for the management of strongly interacting species such as the noisy miner (Manorina melanocephala), which structure ecological communities through aggressive exclusion of other taxa from areas that they occupy. Aims In Manorina colonies, young females are usually dispersive, while males remain in the natal colony as the philopatric sex. Following removal of individuals from an area, we aimed to determine whether female-biased dispersal, particularly of young females, would result in a more equal sex ratio and a younger age structure in the recolonising population. Methods These predictions were tested by anatomically ageing and sexing 1856 noisy miners that had been experimentally culled in two regions of New South Wales, Australia, to reduce the aggressive impact of this species on other native species. Key results Prior to removal, noisy miner populations were significantly male-biased in both regions (57% and 60%); however sex ratios after each of two removal episodes no longer differed from parity. Immature birds were a dominant feature (65%) of recolonising populations in both regions, however, the age structure of recolonising populations was different in each region, mostly likely due to the respective timing of culls during the year. Furthermore, the culling response in terms of age-specific sex ratio varied between regions. After the final cull, the sex ratio of mature birds had fallen to parity in one region but had become even more male biased (68%) in the other region. There was no sex-ratio bias among immature birds before or after culling. Conclusion These results confirm the expectation that immature birds are more likely to be colonisers, but the expectation of greater female dispersal was equivocal. Implications The differences in response between regions may reflect variation in population density, landscape connectivity or seasonality, highlighting challenges when implementing culling programs for conservation management.