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Nest predation is the most important source of reproductive failure for many bird species, thus placing nests in ‘safe’ locations that minimise predation risk is paramount to maximising fitness. After a nest predation event, some species have been shown to manage the risk of nest predation for subsequent re-nesting attempts by moving to a new location, placing re-nests in areas with increased cover, or changing the height above ground at which the re-nest is placed. The extent to which this is an adaptive behaviour for birds in general is not yet clear, as existing studies are almost exclusively restricted to northern hemisphere species and species that do not breed cooperatively. Here, we examined the re-nesting behaviour of Bell Miners (Manorina melanophrys), a species of honeyeater endemic to Australia that is both multi-brooded and also frequently re-nests soon after nesting failure; females can build up to five nests in a breeding season. We tested if these females managed within-season nest predation risk by changing nest site characteristics (height from ground and distance between nests) between successive nesting attempts. We found that female miners did indeed manage predation risk by reducing the height from the ground at which they placed re-nests following predation events, but contrary to our second prediction we found no difference in distances moved to re-nest after females experienced nest predation or successfully rearing young.

Summary The Bell Miner (Manorina melanophrys) occurs in logged eucalypt forest in northern NSW with a dense understorey of the invasive Neotropical shrub Lantana (Lantana camara) that is used for nesting. The link between Bell Miners and Lantana is important as the birds aggressively exclude all smaller and similar-sized birds from their colonies, reducing avian diversity in forest occupied by the species. We monitored the impact of Lantana removal on Bell Miner persistence in several plots in two logged forest sites, along with untreated control plots at one of the sites. Lantana control was successful over 7 years at both sites, with regeneration of native understorey, midstorey and canopy species compensating for the loss of live Lantana cover in the understorey. Bell Miner individuals vacated the treated plots in one site (Creek's Bend) but persisted in the control and treated plots at the second site (Toonumbar National Park). Bell Miner response was correlated with forest structure: birds vacated forest with a sparse understorey ( 15 m) at Creek's Bend, but remained at the site with a dense understorey but sparse midstorey and canopy at Toonumbar. We therefore predict that forest restoration that simultaneously reduces Lantana understorey and increases midstorey density will be most successful in reducing the abundance of the despotic Bell Miner and increasing avian diversity in rehabilitated sites.

Many hypotheses have been proposed to account for cooperative behaviour, with those favouring kin selection receiving the greatest support to date. However, the importance of relatedness becomes less clear in complex societies where interactions can involve both kin and non-kin. To help clarify this, we examined the relative effect of indirect versus key direct benefit hypotheses in shaping cooperative decisions. We assessed the relative importance of likely reciprocal aid (as measured by spatial proximity between participants), kin selection (using molecular-based relatedness indices) and putative signals of relatedness (vocal similarity) on helper/helper cooperative provisioning dynamics in bell miners (Manorina melanophrys), a species living in large, complex societies. Using network analysis, we quantified the extent of shared provisioning (helping at the same nests) among individual helpers (excluding breeding pairs) over three seasons and 4290 provisioning visits, and compared these with the location of individuals within a colony and networks built using either genetic molecular relatedness or call similarity indices. Significant levels of clustering were observed in networks; individuals within a cluster were more closely related to each other than other colony members, and cluster membership was stable across years. The probability of a miner helping at another’s nest was not simply a product of spatial proximity and thus the potential for reciprocal aid. Networks constructed using helping data were significantly correlated to those built using molecular data in 5 of 10 comparisons, compared to 8 of 10 comparisons for networks constructed using call similarity. This suggests an important role of kinship in shaping helping dynamics in a complex cooperative society, apparently determined via an acoustic ‘greenbeard’ signal in this system.

The bell miner (Manorina melanophrys) is a despotic honeyeater. Little is known about permanent colonisation in this species. Our banding study aimed to document changes in species richness over time and capture the effect of a despotic species. Our study is the first to document individual movements that led to the establishment of two permanent breeding colonies over 22 years of banding. One site in the Australian Botanic Garden, Mount Annan where birds moved in, compared to Camden Airport where bell miners have been present since the mid-1950s. Over the first 12 years there were three short-term visits by small groups of bell miners into the Conservation Woodland Area, in the Australian Botanic Garden, Mount Annan, for a maximum of three months. Retrapping of individuals showed that birds were first-year and older and travelled 2.1–4.2km. In 2016, both colonies contained over 120 birds and species richness changed, particularly of canopy-foraging species. At the Australian Botanic Garden, Mount Annan, 18 bird species decreased in number, with three no longer present (F33,34=2.50, P=0.00). Two other species also colonised the area and 13 increased in number. Understorey species such as the satin bowerbird, the eastern spinebill and the superb fairy-wren increased significantly. Movements of 0.3–1.0km were also detected at the Camden Airport site. At Camden Airport, five species decreased in number and four species increased but species richness stayed the same. Interestingly, bell miners decreased in number. After a heat wave in Summer 2016/17, bell miner weights declined and the colony disappeared. No eucalypt defoliation was observed in November 2017. Understorey modifications occurred only in areas away from the study sites during this project, suggesting that weather and food resources are the main contributing factors to colony establishment and longevity.

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.

Accurate determination of the population density of key focal species is necessary for monitoring the success of management programs and ecosystem health across a wide range of contexts. Unfortunately, many key taxa are visually cryptic and thus difficult to count using traditional observation-based techniques. Bell miners (Manorina melanophrys), are just such a species. They are widespread throughout south-eastern Australia, yet they are critical to monitor given their association and potential causal link to spreading vegetative dieback in this region. A new passive acoustic monitoring technique was trialled by testing its ability to determine population densities of bell miner colonies via counting the distinctive ‘tink’ vocalization of this species. This call was given at a constant rate per individual, and at a common amplitude across 10 colonies throughout the entire geographic range of the species. Theoretical sound transmission and playback trials through typical habitat determined that any bird within a 50-m radius of the recorders used would be louder than 70 dB, enabling this threshold amplitude to be used to determine the number of birds in a 50 m radius of the recorder. Field trials of the acoustic protocol versus human observers using traditional visual surveys found that passive acoustic monitoring was able to detect more individuals, using a less expensive protocol that drastically reduced the need for observer training or expertise. Sound therefore offers a reliable method for determining the density of this vocal, but visually cryptic species. We present methods for calibrating recording devices and detecting calls louder than species-specific thresholds using readily available freeware, enabling our methods to be easily adapted to census a variety of acoustically distinctive species, offering a more effective, yet lower cost and in our case more efficient census technique for surveying difficult species.

Mapping the location and extent of forest at risk from damaging agents or processes assists forest managers in prioritizing their planning and operational mitigation activities. In Australia, Bell Miner Associated Dieback (BMAD) refers to a form of canopy decline observed in eucalypt crowns occupied by colonies of bell miners ( Manorina melanophrys ). High densities of bell miners are associated with decreased avian abundance and diversity and an increase in psyllid abundance on crown foliage. BMAD has recently been nominated as a key threatening process in New South Wales (NSW). Consequently, a modelling system for predicting bell miner distribution in coastal eucalypt forests of NSW has been developed. The presence or absence of bell miners was recorded in 130 plots located within a 12,800 ha catchment study area containing a range of eucalypt forest types. The modelling system was produced by integrating a machine learning software suite (WEKA), and the statistical software R within the geographic resources analysis support system (GRASS) geographical information system (GIS). The variable modelled was the binary variable: presence or absence of bell minors. Six modelling techniques (Logistic regression; generalised additive models; two tree-based ensemble classification algorithms, random forest and Adaboost and Neural Networks) were integrated with airborne laser scanning; SPOT 5 and topographic derived variables. Model evaluation and parameter selection were measured by three threshold dependent measures (sensitivity, specificity and kappa) and the threshold independent Receiver Operator Curve (ROC) analysis. The final presence and absence maps were obtained through maximisation of the kappa statistic and applied at a resolution of 10 m across the entire catchment study area. For this data set, the most accurate algorithm for predicting the distribution of bell miner colonies was random forest (kappa = 0.84; ROC area under curve = 0.97). Variables most commonly selected in the six models were the laser scanning metrics; coefficient of variation, skewness, and the 10th and 90th percentiles derived from the shape of the height frequency distribution which, in turn, is directly influenced by vertical structure of the forest. An image textural statistic based on the shortwave infrared (SWIR) band of SPOT 5 was also commonly selected by the models. The SWIR band is sensitive to vegetation and soil moisture content. These models predicted that forest stands with a sparse eucalypt canopy over a moist, dense understorey were susceptible to being colonised by bell miners and hence BMAD.

Bell miner–associated dieback (BMAD) is a form of canopy decline involving bell miner (Manorina melanophrys) colonies on the eastern coast of Australia. The association can include an understorey of lantana (Lantana camara) preventing eucalypt regeneration. To date, comparatively little is known about the effects of these processes on mammal diversity and abundance. We therefore considered the effects of BMAD and lantana presence on ground mammals and insectivorous bats in four forest sites within New South Wales. These were monitored in association with a restoration project for the treatment of lantana that used glyphosate spraying to kill lantana in half of six 50m×50m quadrats per site (three control and three treated). Passive bioacoustic recorders, infrared cameras and Elliott traps were used to survey understorey fauna over four consecutive nights during each season. We found a greater number of small ground-dwelling and large mammals in control areas with an intact understorey of lantana relative to areas where lantana had been treated. However, insectivorous bats were not influenced by lantana presence. Our results suggest that ground-dwelling mammals benefit from the presence of lantana, as it may provide structural complexity that reduces predation risk and/or provides a food resource.

The hypothesis that bell miners (Manorina melanophrys) improve their alloparenting skills during the period spent as helpers was tested by means of comparing: a) the frequency of nestling care activities, b) the frequency of nestling attendance “mistakes”, c) the gizzard contents and items brought to nestlings, and d) interactions at the nest with the breeders, for helpers of different ages. Results show that young birds made fewer feeding visits to the nestlings and made more empty (i.e. non-feeding) visits than older helpers. The few “mistakes” detected were also made by young helpers. The proportion of food items brought to the nestlings consisting of arthropods was smaller for very young helpers (≤ 3.8 months) than for older helpers. Sexually mature helpers also had relatively more arthropods than psyllid sugary covers (a food item very easy to locate and capture) in their gizzards than immatures in winter, but this difference was marginally not significant. Young helpers must learn their place within the group hierarchy, but no clear division of labor in the alloparental activities studied was detected, which might have increased the effect of learning during the period birds spent as helpers.

In an analysis of the pattern of helping at the nest in bell miners (Manorina melanophrys), Clarke (1989) examined five hypotheses that could explain the evolution of helping behaviour in this species. We applaud the attempt by Clarke to consider many different hypotheses, but believe that more careful formulation of the hypotheses, more appropriate statistical analyses, and eventual experimental testing are required before his conclusions can be accepted.

The amount of aid a helper gave a single brood varied significantly according to the helper's age, sex and breeding status. The rate at which non-breeding helpers fed a brood increased as the helpers aged. Male helpers and unmated breeding-age helpers gave aid at higher rates and to a greater number of different breeding pairs than did female helpers and mated helpers. Breeding pairs which were assisted by six or more helpers during the fledgling period produced more independent offspring per attempt than did pairs assisted by fewer helpers. It is suggested that the helpers reduced the provisioning burden of the breeding pair. Individual helpers fed nondescendant kin at significantly higher rates than they fed recipients of no known genetic relationship. However, most helpers also aided broods to which they had no known genetic relationship. Their pattern of aid distribution amongst such recipients was neither random nor related to the proximity of the recipients. Naturally ‘widowed’ female breeders paired preferentially with the unrelated, unmated, breeding-age male which had provided the most aid to their previous broods. The pattern of aid distribution by bell miners was most accurately predicted by the hypotheses that helpers gain indirect fitness benefits by aiding kin (whenever appropriate kin were present, which was predominantly when an individual was young), and direct fitness benefits through aiding breeders as the helpers approached sexual maturity, thereby increasing the likelihood of being accepted to fill a breeding vacancy.

Jamieson & Craig (1987) have argued that the feeding of nestlings by nonparental birds may simply be an unselected consequence of delayed dispersal in cooperatively breeding birds in which philopatric individuals are responding to the stimulus of begging young in their vicinity (see also Jamieson 1986, 1989). Jamieson & Craig (1990) recently criticized my attempt to examine what they describe as this “unselected” hypothesis of Williams (1966) and several selectionist (or adaptive) hypotheses for the current utility of helping behaviour in the bell miner (Manorina melanophrys) (Clarke 1989). In this paper I address specific issues raised by Jamieson & Craig (1990), especially whether the unselected hypothesis is an adequate explanation of the pattern of helping in the bell miner. I will also attempt to highlight the difficulty of formulating specific predictions from the unselected hypothesis and the apparent ease with which it can be modified to accommodate departures from its general predictions.

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.

Trials were conducted to regenerate declining forests infested with lantana and psyllids near Mt Lindesay in northern New South Wales. Two years after treatment, trees in both controls and treated stands were significantly healthier. These changes were attributed mainly to drought-breaking rains. However, psyllid populations (as indicated by counts of bell miner, Manorina melanophrys) were higher in trees retained in treated areas than in control trees (in untreated areas), suggesting that treatments had not arrested chronic decline. Tree regeneration in treated areas was very variable and was dominated by brush box (Tristaniopsis confertus). Intense fire reduced lantana cover to a very low level in the year after treatment. Lantana cover doubled in the following year, but at 5% was still significantly less than before treatment (more than 80%). Declining eucalypt stands lack seed, and seedlings should be planted at high stockings (more than 1000 ha-1) to achieve canopy closure before lantana can recover to high levels. The cost of rehabilitating severely degraded stands, comprising 20% of the treated area, was AUD3500 ha-1. It appears unlikely that canopy closure will be achieved in the remainder of the treated area where recovery of shrubs and vines may make it difficult to reintroduce low-intensity fire. It is important to use low-intensity fire where possible to maintain essential ecological processes in dry to moist eucalypt forests so that they do not suffer canopy decline and shrub invasion.

Models of parent–offspring conflict and nestling begging honesty often assume that signaling is associated with increased predation risk. However, little evidence exists that begging actually increases predation in the context in which it evolved, especially when the potentially modulating effects of parental defense are taken into account. We measured the cost of begging in cooperatively breeding bell miners (Manorina melanophrys) by baiting 168 inactive nests with a wax egg and broadcasting sounds from nearby speakers. Nests were randomly assigned to 1 of 3 treatments: silence, unmanipulated begging calls, or shaped white noise pulses that matched the amplitude envelope of each corresponding begging call. Moreover, half of the nests were placed outside and half inside bell miner colonies, where miners vigorously mob potential nest predators. Predation was not influenced by vegetation cover, distance of the nest from the speaker, or placement inside the colony. Sounds were costly, however, as nests broadcasting begging signals or white noise were predated more often and more quickly than silent controls. Contrary to theoretical predictions regarding ‘‘stealthy’’ design, we found that predators were just as likely to locate nests with broadband white noise playback as nests broadcasting begging signals. Further, there was an interaction between playback amplitude and predator type (avian vs. rodent): Louder playback led to decreased nest survival for those taken by avian predators. As increased begging drives provisioning rates in many species, including bell miners, this reveals an inescapable trade-off between nestling begging intensity, parental provisioning effort, and predation risk. Key words: costs of signals, parent–offspring conflict, predator–prey interactions, signal design. [Behav Ecol]

Bell Miners (Manorina melanophrys) are cooperatively breeding honeyeaters that defend colonies from potential predators and competitors. Despite extensive study of the social organisation of Bell Miners, little is known about the social dynamics of expansion of colonies and establishment of new territories in this species. We took advantage of an individually marked, molecularly sexed and genotyped study population to examine the social dynamics of two extensions of the range of a colony. These observations indicated colonisation of new areas by colony members was accomplished via two different pathways, either the efforts of a breeding pair and its pre-existing contingent of helpers, or a group of unmated males. Only the former bred, with greater numbers of individuals related to the breeding pair acting as helpers in new areas initially. Most colonists were males that lacked a breeding position. Ultimately both expansions of the colony proved to be temporary, with colonists returning to their former home-ranges after six months.

High densities of bell miners (Manorina melanophrys) are known to accelerate dieback in eucalypt forests presumably through their negative impact on other avian insectivores and predatory insects. Some areas of moist eucalypt forest that are managed for sustained timber production also support very high densities of bell miners. In this study, we quantified the relative population density of bell miners in forests, and investigated the relationship between bell miner population density, the relative population density of other birds and species richness. A study site of 900 ha was selected in Olney State Forest on the Central Coast of New South Wales (33°7′ S, 150°22′ E), an area that has been managed for timber production since the 1920s. Monthly census counts were carried out over a 16-month period to include diurnal and seasonal variation. Bell miner population density ranged from 14–38 birds/ha and was found to be negatively correlated with diversity of other species. A linear empirical relationship was found between bird species richness (y) and bell miner relative population density (x) by the equation y = −0.12x + 7.78 (R = 0.9638, n = 8, P Experiments elsewhere in which bell miners were removed from eucalypt woodland plots have shown a return of avian biodiversity and enhanced tree growth, and this study provides an empirical relationship describing the impact on avian diversity for a given forest. We recommend a test of the hypothesis that manipulation of the understorey during burning and logging, could be used to reduce bell miner population levels in wet eucalypt forests, with corresponding benefits to avian biodiversity and tree growth. Work toward these ends has been initiated by the bell miner Associated Dieback Working Group in northern NSW at present and our findings support their strategy.

Cooperatively breeding bell miners (Manorina melanophrys) have numerous male helpers assisting at multiple nests. Helpers are often related to the brood they aid, consistent with kin selection. However, there are also unrelated helpers for which other direct fitness benefits are likely to accrue. Bell miner nestlings can become infested by the larvae of a parasitic fly (Passeromyia indecora), which reduce growth and can be fatal. We investigated the amount of time that breeding pairs and helpers closely inspected nests and preened nestlings, behaviors apparently directed at detecting and removing parasites, a form of helping previously unstudied in a cooperative bird. Female breeders provided the greatest antiparasite effort, with breeding males and helpers not differing in effort regardless of their relatedness to the breeding female or brood. We also experimentally infested nests with nonparasitic flies and larvae. All individuals removed the introduced ‘‘parasites’’ if and when they encountered them. Compared with control sessions, inspection effort increased for all birds immediately after the experimental infestations, but only for a short, 5-min period. Further, we detected no changes in helper antiparasite behaviors after the temporary experimental removal of either breeding females or males. Such consistent helping behavior, independent of relatedness and potential audience effects, suggests that antiparasite behavior in bell miners is not particularly kin directed or operating as a signal of helper quality. Our results instead suggest that helper antiparasite effort appears to represent adaptive investment in the welfare of the brood, consistent with direct fitness benefits from group augmentation. Key words: dipteran infestation, helping at the nest, parental care, Passeromyia, signaling hypotheses. [Behav Ecol]

Forest attributes including canopy health and stand structure were visually assessed to identify features commonly associated with the bell miner (Manorina melanophrys, Meliphagidae), a cooperatively breeding, insectivorous honeyeater endemic to south-eastern Australia. A stratified random sampling methodology, using a combination of SPOT5 satellite imagery and a 25-m pixel digital altitude model, was used to establish 130 circular plots 40 m in diameter within a 12 800 ha study area in the Watagan mountain range, central coast of New South Wales (NSW). In this study site, the presence of bell miners was significantly associated with unhealthy eucalypt crowns. This supports the proposition that a dieback syndrome known as bell-miner-associated dieback (BMAD) exists in central coastal forests of NSW. Our results also demonstrate a strong association of a sparse eucalypt canopy over a dense lower midstorey with the presence of bell miners. Altitude and fire frequency were negatively correlated with bell miners while the topographical wetness index was positively correlated with bell miners. Logistic regression was used to quantify the effects of a series of explanatory variables including tree species, forest structure variables and selected topographic variables. Although there were significant differences in the ranking of crown condition between eucalypt species, tree species was not selected in the final model. The final variables identified by the logistic regression for the presence of bell miners included sparse eucalypt overstorey cover, dense lower midstorey cover, the absence of young vigorous regrowth trees and higher values of the topographic wetness index. Based on the results of our survey we discuss practical options for managing the forest dieback syndrome associated with bell miners in the central coast region of NSW and an approach to mapping forests at risk from BMAD.

Despite many studies on the evolution of cooperative breeding and helping at the nest, relatively few have explored the possibility that helping functions as a signal to gain social advantage within groups (the ‘‘pay to stay’’ and ‘‘social prestige’’ hypotheses). One of the most promising candidates for such a signaling system is the cooperatively breeding bell miner, Manorina melanophrys. Large numbers of unrelated helpers attend multiple nests while giving individually identifiable vocalizations, breeding females usually remain within monitoring distance of the nest area, and females often re-pair with the hardest working male helper after the death/removal of their breeding partner. We examined the possibility that helping operates as a signal by temporarily removing the potential audience: the breeding male or the breeding female. However, there was no discernable change in provisioning behavior of helpers, relative to control periods. We also simulated the presence of the removed birds through playbacks of their individual-specific calls and again found no effect on others’ visit rates, prey types, load size, and a variety of other behaviors at the nest. If either signaling hypothesis explained helping in this system, we might have expected facultative decreases in conspicuous provisioning behaviors when one or other potential audience was absent. Thus, despite possessing many of the prerequisites of a signal-based helping system, there is no evidence for such a phenomenon in bell miners. Cooperation in these groups of mixed relatedness may instead be driven by a combination of kin selection and direct benefits via group augmentation and/or pseudoreciprocity. Key words: nestling provisioning, cooperative breeding, pay to stay, signaling hypotheses, social prestige. [Behav Ecol]

Various interactions appear to be involved in bell miner associated dieback (BMAD) of eucalypts. Native bell miner birds (Manorina melanophrys) defend the psyllids from predation by other birds while a dense understorey (notably Lantana camara) appears to favour the bell miners. The understory is likely to influence soil nutrient availability to the trees by changing the carbon to nitrogen ratio. We investigated the link between soil and leaf nutrient status and crown health as measured by crown index (CI) for Eucalyptus propinqua. Study sites included Bald Knob State Forest (SF), Donaldson SF, Mt Lindesay SF around Woodenbong and two locations on a Toonumbar private property in north-eastern New South Wales. Comparison of E. propinqua leaf macro-and micronutrient status using the paired data sign test detected leaf nutrient differences between lightly and severely BMAD-affected tree crowns. Single and multivariate analysis investigated nutrient association with CI. Sign test results across all sites indicated that leaf iron content in trees with low CI (less healthy trees) was significantly higher (P = 0.01) than in healthy trees. In the three SFs the affected crowns also had significantly higher nitrogen to potassium ratios (P = 0.02). Other elements correlated with low CI were low boron (P = 0.06) across all sites and high zinc (P = 0.09) and low sodium values (P = 0.09) for Toonumbar sites. The correlation between soil and leaf nutrients was not significant and we found no significant correlations between soil nutrients and CIs. We did not detect any clear association between understorey (L. camara) and soil nutrients. During leaf sampling we found few psyllids but many concealer moth caterpillars. The scarcity of psyllids during sampling, inconclusive nutrient cycling results and nutrient correlations with CI were likely to be due to drought. Resampling under normal weather conditions with more typical organic matter decomposition rates is recommended.

False feeding,' where helpers arrive at nests with food but fail to provision the young, has been reported in several cooperative species. This and other potentially 'deceptive' behavior has been interpreted as indicating that helping may operate as a signal within such social groups. We critically examine these phenomena in the provisioning behavior of the bell miner Manorina melanophrys. Exces- sively close observation distances can artificially elevate the rate of false feeding in this (and other) species, but once this had been accounted for, there was little evidence for any 'deceptive' behavior by helpers or breeders. Natural and experimentally induced variation in the presence of a potential conspecific audience at the nest did not have any consistent influence upon the rate of false feeds, which was low at 7.94% of 6,880 nest visits. Instead, encountering unexpectedly low levels of brood demand provided a more parsimonious explanation for those visits where helpers failed to feed nestlings or ate the food themselves. Failure to completely transfer a load to nestlings was more likely when the load contained a high proportion of sticky lerp, indicating a simple prey-transfer problem. Finally, individu- als that arrived at nests without prey were often members of neighboring breeding pairs, suggesting that these few non- feeding visits may instead involve an information-gathering function. We, therefore, suggest that future studies explicitly exclude the possibility of observer disturbance and all aspects of normal provisioning behavior before applying the terms 'false feeding' or 'deceptive' and inferring anything more than straightforward helping at the nest.

Acoustically-mediated individual discrimination has been the focus of much investigation in ornithology. For cooperatively breeding species, strong selection pressure favouring individual recognition during acts of altruism is predicted under many of the most interesting hypotheses proposed to account for helping behaviour. We investigated differences in 157 calls given by 12 different individuals as they provisioned nestlings, including both breeding and helper bell miners Manorina melanophrys (Meliphagidae), a cooperatively breeding honeyeater endemic to south-eastern Australia. Individual differences were apparent in all 15 call parameters analysed, many with a high level of repeatability. Moreover, the information capacity of mew calls allows as many as 515 different signatures to exist in the system. As many parameters showed strong sex differences, separate discriminant functions were used to predict individual identity within each sex. Five parameters were used in a function that correctly identified over 90% of female calls in both a training (n / 35) and test dataset (n / 11) not used to generate the function. Among males, a separate function used six parameters to correctly assign individual identity in 89.3% (n /84; training) and 77.8% (n /27; test) of cases. Three original parameters, including spectral and spatial characteristics, were highly correlated with functions predicting identity in both sexes. The accuracy of functions was not influenced by a signaller’s sex, breeding status, or by sampling period which was spread over as much as two breeding seasons within individuals. Significant potential therefore exists for bell miners to use these simple provisioning calls in individual discrimination. If this is the case, call information also has the potential to be used by receivers as predicted by signalling hypotheses proposed to account for cooperative helping behaviour, such as the pay-to-stay and social prestige hypotheses.

Brooding of nestlings in cooperatively breeding bird species may be disrupted by the attendance of helpers at the nest. We studied the factors that influence brooding in the cooperatively breeding honeyeater, the Bell Miner (Manorina melanophrys), and how nest attendants interacted with the bird brooding at the nest. Only the breeding female brooded nestlings, despite helpers assisting with many other aspects of the care of nestlings. The number of bouts of brooding by the female per hour was dependent upon the age and number of nestlings, ambient air temperature, and the number of Bell Miners visiting the nest. Behaviours performed by the female differed significantly between brooding and non-brooding visits. These findings are consistent with earlier studies of species with simpler biparental care. However, the complexity of meeting the nutritional and thermoregulatory requirements of nestlings in a cooperatively breeding species is demonstrated by changes in the behaviour of nest attendants when females were brooding, and by the different responses of females to different nest attendants. Nest attendants delayed visiting the nest when the female was brooding. However, if an attendant did visit the nest while the female was brooding, she was more likely to stop brooding and allow nestlings to be fed if the attendant was the breeding male, rather than a helper, irrespective of whether or not the attendants were close relatives of the nestlings.

The ability to alter primary sex ratios has the potential to increase a breeding individual's fitness. This is certainly true in those cooperative breeders where one sex is both philopatric and helps raise future offspring of its parents. We examined the primary sex ratio variation in the cooperatively breeding bell miner (Manorina melanophrys) in southeastern Australia over six breeding seasons. Male offspring are the philopatric and helping sex in this system and can increase the reproductive output of their parents. Bell miners aggressively defend their territory from all interspecific competitors and by doing so allow food resources to dramatically increase. The increase in phytophagous Psyllidae insects (which secrete a carbohydrate-rich coating that constitutes the major component of bell miner diet) leads to a decrease in tree health, often culminating in death of the tree. Bell miners then move as groups to new areas with low psyllid abundance, and the cycle repeats. Using this predictable temporal variation in food availability, we aimed to determine whether female breeders adjusted the sex ratio of broods to produce more of the philopatric sex when food resources were high and more of the dispersing sex when food resources were low. Our results provide clear evidence for such facultative control of sex ratio by female bell miners. Newly founded colonies are characterized by low food availability and a female-biased primary sex ratio, whereas colonies more than 1 year old have an increased food availability and a male-biased primary sex ratio. We suggest treating forces associated with resource enhancement and competition as opposing sides of a single general principle and suggest that it is necessary to view both the costs and benefits of philopatric individuals within a variable environment. Copyright 2003.

Polygamous mating systems are expected to put sexual partners at greater risk of contracting a sexually transmissible microorganism compared with monogamy. Potentially pathogenic cloacal microorganisms such as Candida albicans, Chlamydia, coliforms and non-lactose-fermenting bacteria were studied during the non-breeding and the breeding seasons in four avian host species: two polygamous (Malurus cyaneus and Sericornis frontalis) and two monogamous (Manorina melanophrys and Neochmia temporalis). The results indicate that the highly polygamous M. cyaneus harbours more coliform and non-lactose-fermenting bacteria (which can cause disease) in its cloaca than do the polyandrous S. frontalis and the monogamous M. melanophrys. In addition, we detected higher-intensity levels of the above bacteria in avian cloacae during the non-breeding season than during the breeding season. Although not significant, trends also suggest that monogamous host species are relatively less colonised by cloacal microorganisms than are polygamous host species, whereas the latter also suffer a higher degree of multiple infection than the former.

We examined the sex ratios of adults and nestlings in the cooperatively breeding bell miner Manorina melanophrys. Males were over-represented among helpers (mean of 6.8 male helpers per nest compared to 0.3 female helpers). 58% of nestlings sampled were identified as male using a molecular genetic marker. This was a significant departure from parity, yet the magnitude of the bias varied between years. The beneficial and male-biased nature of helping behaviour in this species and the similar size of male and female nestlings suggest the net cost of raising males is lower than the cost of raising females. Consequently, the male-biased sex ratio of nestlings we observed is consistent with the predictions of the repayment hypothesis that females may bias the production of their young towards the more helpful sex. Difficulties of generating quantitative predictions from repayment models that can be tested in the field are discussed.

Commentaire au sujet du comportement de harcelement du predateur et du risque mortel lie a ce comportement en relation avec differents articles contradictoires. L'auteur rapporte le cas de Manorina melanophrys tue par Dacelo novaguineae au cours d'un harcelement

Cloacal microparasites such as viruses, bacteria and fungi are expected to condition choice of sexual partner, as they can not only affect the expression of secondary sexual traits used in courtship, but they could be also directly transmitted to partners through copulation. We investigated the distribution of three cloacal microparasites (the bacterium Chlamydia psittaci and the yeasts Candida albicans and Kloeckeria sp.) among males and females of the sexually plumage dichromatic Malurus cyaneus and Sericornis frontalis, and the plumage monochromatic Manorina melanophrys. Males tended to be more parasitized than females within species, but the effect was stronger for the sexually dichromatic S. frontalis than for the sexually monochromatic M. melanophrys. In addition, parasitized males of the sexually dichromatic M. cyaneus had more conspicuous ear tufts (a secondary sexual trait used in courtship) than unparasitized males. The above evidence suggest that mate choice may involve a cost in terms of transmission of cloacal microparasites.

The removal of a colony of bell miners Manorina melanophrys from a Eucalyptus radiata forest in Victoria, Australia resulted in an immediate influx of other species of insectivorous birds and a short-term increase in avian diversity and abundance, similar to that reported by Loyn et al. (1983). Once bell miner numbers were greatly reduced on the experimental site, the remaining individuals ceased to exhibit interspecific territoriality and eventually abandoned the site. This suggests that a critical minimum number of individuals is needed to defend a territory. Once bell miners were removed an infestation of Glycaspis sp. psyllids at the site was devoured by the invading insectivorous birds. However, once bell miners recolonised the site, the Glycaspis sp. population returned to close to its former levels. The major reduction in the number of bell miners and psyllids at the site for a period of 10 months did not lead to an improvement in tree health during the 2 1/2 years following the cull. This contrasts with earlier findings by Loyn et al. (1983). Phytophthora cinnamomi (a pathogenic fungus) was present at both the experimental and control sites suffering dieback, and may have been the primary cause of the trees' ill-health and their lack of recovery, despite the reduction in psyllid numbers at the experimental site. Our results highlight the fact that removal of bell miners from a site suffering eucalypt dieback does not guarantee the recovery of the trees, especially if other factors may be contributing to the trees' decline.

We used multi-locus DNA fingerprinting to determine the parentage of 13 broods of Bell Miner (Manorina melanophrys) nestlings. Despite very large contingents of male helpers attending individual nests and living in close proximity to breeding females, we found only one instance of extra-pair paternity in 24 nestlings. The genetic father of the extra-pair nestling was not among the males in our study population. The majority of helpers (67% of 52 cases) were close relatives (r > 0.25) of at least one parent of the brood being provisioned. Helpers were more often closely related to the male than the female parent. Only 17% of cases involved helpers that were apparently unrelated to either of the parents of the broods being aided. We conclude that Bell Miners do not mate promiscuously and that the majority of helpers are close relatives of the breeding pair. Cooperative breeding in Bell Miners seems to have evolved as a system of collateral kinship among the breeding birds and helpers.

The presence of the aggressive, colony-forming honeyeater, Manorina melanophrys (bell miner), in the canopies of unhealthy eucalypts has been well reported. There is, however, some debate as to the actual mechanisms producing these unhealthy trees. To investigate further some of the processes that may be contributing to this form of canopy dieback, two field trials were carried out in Olney State Forest, near Wyong, New South Wales. The study site contained Eucalyptus saligna (Sydney blue gum) with canopy dieback and was occupied by a large colony of bell miners. Close examination of the foliage revealed a large and diverse suite of phytophagous insects, including at least 16 species of psyllid (Hemiptera: Psyllidae). In the first trial, the use of bird exclusion cages over selected branches significantly improved leaf survival compared to leaves exposed to a relatively high density of bell miners. It is proposed that colonization by bell miners may interfere with the efficacy of both other insectivorous birds (through aggressive interspecific territoriality) and the invertebrate predators and parasitoids. Interference with such regulatory factors may enable some phytophagous insect populations to rise to sustained damaging levels. In the second trial, an insecticide application combined with reduced competition from the dense understorey and neighbouring trees was required to significantly improve trunk diameter and crown condition scores. After 12 months, neither treatment, by itself, significantly improved both growth measures. Possibly both treatments were required because the E. saligna trees were suffering from another source of stress (e.g. drought) in addition to the relatively high level of insect attack.

Context The bell miner (Manorina melanophrys) is thought to prefer the dense vegetation of Lantana camara, a dominating noxious weed, to nest in compared with native plant communities in northern New South Wales and south-eastern Queensland. As miner numbers seemed to have increased with increased availability of nesting habitat, larger numbers of despotic bell miners territorially reduce native avian diversity. The resultant high insect numbers in the canopy lead to dieback. It is unknown to what extent the native bell miner relies on lantana for nesting sites and if restoration through removal of lantana, resulting in an influx of native species, changes food availability and thus foraging behaviours. Aims The objective of our study was to understand the relationship between the presence of lantana and bell miners by determining: (1) bell miner behaviours in response to different understorey types; (2) bell miner nesting choices on a broad scale; (3) nesting preference for each site on a broad scale; and (4) whether nest height is related to fledging success. Methods Fifty individual bell miners were observed within five colonies (four containing comparison quadrats of treated and intact lantana as part of a restoration study and one containing water vine for comparison as a pristine site; n=10 per treatment) during four seasons. Five bouts of gleaning, probing or sallying were observed, noting height and plant species. Nest sites were examined over a large area, noting plant species present, nest height and plant height. Key results Bell miners used gleaning as the primary foraging tactic primarily in eucalypts (93%; n=600, mean=13.6m±0.29, s.e.). Bell miners generally nested in understorey vegetation (83.5% of nests observed) at a mean height of 2.7m in 37 different plant species, native and exotic. Nest height did not influence the probability of broods fledging. Conclusions Bell miners exhibit considerable nest plasticity, and the removal of lantana as an oft-used nesting habitat is unlikely to lead to relocation by this species. Implications Instead, future research needs to focus on canopy insect assemblages in bell miner colonies, a potentially more important determinant of bell miner distribution.

Bell Miners Manorina melanophrys are cooperative breeders and occur in discrete colonies. A colony comprised a number of breeding pairs occupying slightly overlapping foraging ranges that they shar...

Plasma concentration of androgens and gonad development were studied in wild cooperatively breeding bell miners (Manorina melanophrys) of different age, sex and social status. Plasma levels of androgens increased with age of birds. For sexually mature (SM) bell miners, androgen levels were higher in breeders than in nonbreeding (NB) helpers (P < 0.005), and they were marginally higher in females than in males (P < 0.10). Thus female breeders showed the highest plasma levels of androgens. This pattern may be explained by an asymmetry between the sexes in the levels of competition needed to reach and defend breeding status; the degree of intra-sexual competition seems to be higher among female bell miners than among males. In general, male breeders had larger gonads than male SMNB helpers; male breeder gonads produced spermatozoa whereas most helpers' gonads did not. However, old (i.e. ≧ 34 months) SMNB male helpers had large gonads producing spermatozoa in spite of having low plasma levels of androgens. We suggest that young male bell miners may be under a “voluntary” mechanism of reproductive suppression perhaps favoured by inbreeding avoidance; although some aggressive interactions observed between very young helpers (about 2 months) and adult members of the breeding unit suggests that a certain degree of imposition also occurs at young ages. Older male helpers may avoid aggression with the male breeder and imposed reproductive suppression, hence the low circulating levels of androgens, but they have the potential to sneak extra-pair copulations. Gonad size decreased during the non-breeding season in both sexes.

Kin selection predicts that helpers in cooperative systems should preferentially aid relatives to maximize fitness. In family-based groups, this can be accomplished simply by assisting all group members. In more complex societies, where large numbers of kin and non-kin regularly interact, more sophisticated kin-recognition mechanisms are needed. Bell miners ( Manorina melanophrys ) are just such a system where individuals regularly interact with both kin and non-kin within large colonies. Despite this complexity, individual helpers of both sexes facultatively work harder when provisioning the young of closer genetic relatedness. We investigated the mechanism by which such adaptive discrimination occurs by assessing genetic kinship influences on the structure of more than 1900 provisioning vocalizations of 185 miners. These ‘mew’ calls showed a significant, positive linear increase in call similarity with increasing genetic relatedness, most especially in comparisons between male helpers and the breeding male. Furthermore, individual helping effort was more heavily influenced by call similarity to breeding males than to genetic relatedness, as predicted if call similarity is indeed the rule-of-thumb used to discriminate kin in this system. Individual mew call structure appeared to be inflexible and innate, providing an effective mechanism by which helpers can assess their relatedness to any individual. This provides, to our knowledge, the first example of a mechanism for fine-scale kin discrimination in a complex avian society.

SummaryThe hypothesis that Bell Miners Manorina melanophrys Meliphagidae when foraging on psyllids selectively consume the sugary cover of the insect (lerp) leaving the nymph behind (the ‘farming’ hypothesis) was tested, using data from the gizzard contents of 122 birds. The ‘farming’ hypothesis predicts that: (a) the gizzards of Bell Miners should contain relatively more lerps than psyllid nymphs; (b) they should have a larger lerps/nymphs ratio than gizzards of other, presumably ‘non-farming’, bird species; and (c) the highest values of lerps/nymphs should be found in adult male Bell Miners during the non-breeding season. None of the above predictions was supported. This preliminary work fails to produce strong evidence for the ‘farming’ hypothesis.

An experimental manipulation of clutch size was carried out on a wild population of the cooperatively breeding Bell Miner (Manorina melanophrys, Meliphagidae) to assess which factor(s) limit clutch size in this species. Results provide some support for the ‘trade-off hypothesis’ since there is a cost of reproduction for the breeding female in terms of loss of body mass. The breeding female performs most of the nestling care. Clutches of three eggs are also laid during the mid-breeding season which is the period most favourable for breeding (i.e. nestlings grow faster). This evidence also supports the ‘intrabrood competition hypothesis’. Clutches that have lost an egg were more likely to be deserted; this may be an antipredator strategy since partial clutch predation has been recorded in the field. Nest predation was high in this study (64.9%), suggesting that many small clutches may be a strategy to decrease the effect of nest predation on reproductive success over the whole breeding season (‘nest predation hypothesis’). Both the ‘trade-off hypothesis’ and the ‘nest predation hypothesis’ may apply in this case since they are not mutually exclusive. The size of the attending group did not greatly affect reproductive success in the short term, although if both age structure and size of the group are taken into account, reproductive success can be better predicted.

Observations of Bell Miner Manorina melanophrys female breeders being fed by one or more nest attendants while the former were incubating or brooding are reported. This behaviour might be the result of some male helpers trying to establish a mating relationship with the breeding female.

Indirect fitness benefits from kin selection can explain why non-breeding individuals help raise the young of relatives. However, the evolution of helping by non-relatives requires direct fitness benefits, for example via group augmentation. Here, we examine nest visit rates, load sizes and prey types delivered by breeding pairs and their helpers in the cooperatively breeding bell miner ( Manorina melanophrys ). In this system, males remain in their natal colony while young females typically disperse, and helpers of both sexes often assist at multiple nests concurrently. We found extremely clear evidence for the expected effect of genetic relatedness on individual helping effort per nest within colonies. This positive incremental effect of kinship was facultative—i.e. largely the result of within-individual variation in helping effort. Surprisingly, no sex differences were detectable in any aspect of helping, and even non-relatives provided substantial aid. Helpers and breeders of both sexes regulated their provisioning effort by responding visit-by-visit to changes in nestling begging. Helping behaviour in bell miners therefore appears consistent with adaptive cooperative investment in the brood, and kin-selected care by relatives. Similar investment by ‘unrelated’ helpers of both sexes argues against direct fitness benefits, but is perhaps explained by kin selection at the colony level.