Trichosurus Vulpecula Research Articles

Major Histocompatibility Complex Class II in the red-tailed phascogale (Phascogale calura)

Diversity in major histocompatibility complex (MHC) genes can be correlated with the level of immunological fitness of an individual or group of individuals. This study tested published primer sets designed to amplify fragments of the MHC Class II DAB and DBB genes to amplify the equivalent gene fragments in red-tailed phascogales (Phascogale calura). Seventeen genomic DNA samples extracted from phascogale muscle tissue were used to amplify the initial DAB and DBB fragments; however, only DAB PCR proved successful. The fragments were 172 bp in length between the primers and had a high level of identity to other known marsupial MHC Class II DAB gene sequences (89–98%), including those of the koala (Phascolarctos cinereus), Tasmanian devil (Sarcophilus harrisii), common brushtail possum (Trichosurus vulpecula) and several wallaby species. Multiple sequence alignment revealed limited variability of MHC Class II genes between the individuals, but eight individual sequences in total. Genomic DNA was subsequently extracted from three fresh red-tailed phascogale scat samples and DAB fragments successfully amplified. The technique will allow for red-tailed phascogales to be sampled non-invasively in the wild and to determine the level of MHC diversity among individuals in the population.

The Use of Polyethylene Glycol in Mammalian Herbivore Diet Studies: What Are We Measuring?

Polyethylene glycol (PEG) has been used to study the intake and digestion of tannin-rich plants by mammalian herbivores because it preferentially binds to tannins. However, it is not clear whether the responses of herbivores to dietary PEG is due to increased protein availability from the release of tannin-bound protein, amelioration of tannin effects, or whether PEG also may bind to other compounds and change their activity in the gut. We used three native New Zealand tree species to measure the effect of PEG on the amount of foliage eaten by invasive common brushtail possums (Trichosurus vulpecula) and on in vitro digestible nitrogen (available N). The addition of PEG increased the in vitro available N content of Weinmannia racemosa foliage, and possums ate significantly more PEG-treated foliage than untreated foliage. However, possums also ate more PEG-treated Fuchsia excorticata foliage, even though PEG did not increase in vitro available N in this species. Possums ate very little Melicytus ramiflorus, regardless of PEG treatment, even though M. ramiflorus contained the highest concentration of in vitro available N. These results prompted us to use PEG and a protein supplement, casein, to manipulate the available N concentration of diets containing ground eucalypt foliage, a well-studied food species for possums. Again, the response of possums to PEG was independent of changes in in vitro available N. In addition, altering the protein content of the diet via the addition of casein did not affect how much food the possums consumed. We conclude that the effects of PEG on dry matter intake by mammalian herbivores are not due solely to the release of tannin-bound protein. There is need for a better understanding of PEG-tannin interactions in order to ensure that the use of PEG in nutritional studies does not outstrip an understanding of its mechanisms of action.

Sex difference in the survival rate of wild brushtail possums (Trichosurus vulpecula) experimentally challenged with bovine tuberculosis

The main wildlife reservoir of bovine tuberculosis (TB) in New Zealand is the introduced brushtail possum (Trichosurus vulpecula), with spillover of infection from possums to livestock being regarded as the largest barrier to eradicating TB from the country. Past studies have experimentally challenged possums with Mycobacterium bovis (the causative agent of TB) to quantify infection parameters. However, the challenge models used are invariably non-representative of natural infection due to their resulting in much faster rates, and different clinical patterns of disease progression. We monitored the survival of 16 wild free-living possums, fitted with VHF mortality collars and experimentally challenged with a new model, out to six months post-challenge. The aim was to assess whether the new model does indeed result in an ongoing pathogenesis trajectory that is more reflective of natural TB in possums. The mean survival period of challenged possums (~4.6months) did not differ from that estimated for wild free-living possums with naturally acquired TB. In addition, and unexpectedly, infected males survived on average for five weeks longer than females. This significant difference has not been previously observed in experimental trials with other TB/possum challenge models. If this is reflective of natural disease (as is the survival period produced by the percutaneous challenge model), TB infected males in the wild may be generating more secondary cases of infection than infected females. This insight has important implications for understanding the dynamics of, and managing, the disease in its New Zealand wildlife reservoir.

Foliar Nutritional Quality Explains Patchy Browsing Damage Caused by an Invasive Mammal.

Introduced herbivores frequently inflict significant, yet patchy damage on native ecosystems through selective browsing. However, there are few instances where the underlying cause of this patchy damage has been revealed. We aimed to determine if the nutritional quality of foliage could predict the browsing preferences of an invasive mammalian herbivore, the common brushtail possum (Trichosurus vulpecula), in a temperate forest in New Zealand. We quantified the spatial and temporal variation in four key aspects of the foliar chemistry (total nitrogen, available nitrogen, in vitro dry matter digestibility and tannin effect) of 275 trees representing five native tree species. Simultaneously, we assessed the severity of browsing damage caused by possums on those trees in order to relate selective browsing to foliar nutritional quality. We found significant spatial and temporal variation in nutritional quality among individuals of each tree species examined, as well as among tree species. There was a positive relationship between the available nitrogen concentration of foliage (a measure of in vitro digestible protein) and the severity of damage caused by browsing by possums. This study highlights the importance of nutritional quality, specifically, the foliar available nitrogen concentration of individual trees, in predicting the impact of an invasive mammal. Revealing the underlying cause of patchy browsing by an invasive mammal provides new insights for conservation of native forests and targeted control of invasive herbivores in forest ecosystems.

Demonstration of the scalar property of timing with possums (Trichosurus vulpecula).

Many diverse species have demonstrated interval timing, the ability to respond appropriately to time in the range of seconds to minutes, suggesting that an ability to time is adaptive. The peak procedure is a common method of studying interval time perception. In the peak procedure, animals experience a mix of fixed-interval (FI) and extinction (EXT) trials. On EXT trials, responding typically increases to a peak at the time the FI schedule would normally deliver reinforcers before decreasing. Responding on different FI schedules within the peak procedure has been found to conform to Weber's law, whereby response variability is proportional to the length of the fixed interval. We conducted possibly the first investigation of the timing abilities of a marsupial common to Australia and New Zealand, the brushtail possum (Trichosurus vulpecula), using FI 15-, 30-, and 60-s schedules of reinforcement in the peak procedure. Response rates on EXT trials peaked at the time of usual reinforcer delivery, decreasing at longer time intervals, and were well fit by 3-parameter Gaussian curves, demonstrating the ability of possums to respond to time-based stimuli. Coefficients of variation suggested that the ability of possums to time was less accurate than that of mammals, but similar to that of birds, invertebrates, and reptiles. Coefficients of variation did not differ consistently over increasing FI intervals, showing that timing responses of possums likely conforms to the scalar property of timing also shown by other species. (PsycINFO Database Record

Incorporating Field Studies into Species Distribution and Climate Change Modelling: A Case Study of the Koomal Trichosurus vulpecula hypoleucus (Phalangeridae).

Species distribution models (SDMs) are an effective way of predicting the potential distribution of species and their response to environmental change. Most SDMs apply presence data to a relatively generic set of predictive variables such as climate. However, this weakens the modelling process by overlooking the responses to more cryptic predictive variables. In this paper we demonstrate a means by which data gathered from an intensive animal trapping study can be used to enhance SDMs by combining field data with bioclimatic modelling techniques to determine the future potential distribution for the koomal (Trichosurus vulpecula hypoleucus). The koomal is a geographically isolated subspecies of the common brushtail possum, endemic to south-western Australia. Since European settlement this taxon has undergone a significant reduction in distribution due to its vulnerability to habitat fragmentation, introduced predators and tree/shrub dieback caused by a virulent group of plant pathogens of the genus Phytophthora. An intensive field study found: 1) the home range for the koomal rarely exceeded 1 km in in length at its widest point; 2) areas heavily infested with dieback were not occupied; 3) gap crossing between patches (>400 m) was common behaviour; 4) koomal presence was linked to the extent of suitable vegetation; and 5) where the needs of koomal were met, populations in fragments were demographically similar to those found in contiguous landscapes. We used this information to resolve a more accurate SDM for the koomal than that created from bioclimatic data alone. Specifically, we refined spatial coverages of remnant vegetation and dieback, to develop a set of variables that we combined with selected bioclimatic variables to construct models. We conclude that the utility value of an SDM can be enhanced and given greater resolution by identifying variables that reflect observed, species-specific responses to landscape parameters and incorporating these responses into the model.

Movements and habitat preferences of pests help to improve population control: the case of common brushtail possums in a New Zealand dryland ecosystem.

Introduced brushtail possums are controlled in New Zealand to mitigate their spread of bovine tuberculosis in livestock. Given the low rainfall and extreme variation in seasonal temperatures in dryland areas of the South Island, the habitats of possums in these areas differ in many respects from those in the rest of New Zealand. We investigated the movements and habitat preferences of possums at two dryland sites to identify where they aggregate following population control by using GPS collars and cards chewed by possums. At one site, possum numbers were reduced from high levels by 65%, and at the other site, possums had already been reduced to low levels for some time beforehand but were further reduced to maintain them at low levels. This resulted in different possum densities. Possum home ranges were about 3 times smaller at the higher-density site, but average ranges expanded by 27% following initial control. Home ranges were already large at the lower-density site but did not expand further after maintenance control. No preference for habitat types was apparent at the higher-density site, but at the lower-density site possums selected rock and shrubby habitats and avoided open grassy areas. Home range sizes and habitat preferences were density dependent: the lower the density, the larger was the home range; and habitat preferences were highly variable between individuals, but less so for possums at low density. Preference for shrubs and rocks is likely to benefit population control if population control devices are focused on these habitat types. © 2016 Society of Chemical Industry.

Tattoo pens as a low‐cost approach to in‐field permanent identification of medium‐sized mammals

ABSTRACTReliable identification of individual animals is a primary requirement of population research where data consist of recaptures. Tattooing is a simple and cost‐effective method for permanently marking many mammal species with minimal negative effects, unlike other marking methods, which are often invasive or harmful. Here, we investigate whether a battery‐operated tattoo pen designed for rabbits (Leporidae) is an effective, minimally invasive and low‐cost alternative to other forms of marking and tattooing, which can be successfully applied in the field without altering capture rates. We used the “Rabbi‐tatt” rabbit tattoo pen (Bass Equipment Company, Monnett, MO, USA; http://www.bassequipment.com) to apply identification marks to the ears of northern brown bandicoots (Isoodon macrourus) and common brushtail possums (Trichosurus vulpecula) captured between January 2013 and May 2015 in conservation reserves near Brisbane, Queensland, Australia. Recapture rates did not differ between within‐week recapture rates where tattooing was not used, compared with periods where tattooing was used. During the tattooing period, 50% of possums and 67% of bandicoots were recaptured at least once and many displayed behavior indicative of trap‐happiness after tattooing. The use of the battery‐operated tattoo pen on mammals addresses a number of difficulties associated with tattoo pliers and other forms of permanent marking. We conclude that tattoo pens are a viable method for simply and cost‐effectively marking appropriate species in a minimally invasive way. © 2016 The Wildlife Society.

Species- and site-specific impacts of an invasive herbivore on tree survival in mixed forests.

Invasive herbivores are often managed to limit their negative impact on plant populations, but herbivore density – plant damage relationships are notoriously spatially and temporally variable. Site and species characteristics (both plant and herbivore) must be considered when assessing the potential for herbivore damage, making it difficult to set thresholds for efficient management. Using the invasive brushtail possum Trichosurus vulpecula in New Zealand as a case study, we parameterized a generic model to predict annual probability of browse‐induced mortality of five tree species at 12 sites. We compared predicted and observed tree mortality for each species + site combination to establish herbivore abundance – tree mortality thresholds for each site on a single and combined tree species basis. Model results indicated it is likely that possum browse was the primary cause of all tree mortality at nine of the 12 species‐site combinations, allowing us to estimate site‐specific thresholds below which possum population numbers should be reduced and maintained to keep tree mortality under a predetermined level, for example 0.5% per year. The browse model can be used to set site‐ and species‐specific management action thresholds, and can be adapted easily for other plant or herbivore species. Results for multiple plant or herbivore species at a single site can be combined to create conservative, site‐wide management strategies, and used to: determine which sites will be affected most by changes in herbivore abundance; quantify thresholds for herbivore management; and justify expenditure on herbivore control.

Effects of entrance size, tree size and landscape context on nest box occupancy: Considerations for management and biodiversity offsets

The effectiveness of nest boxes as a management and biodiversity offset tool remains equivocal and controversial. Improving nest box programs requires urgent empirical research to identify the spatial factors that affect occupancy outcomes. Understanding which fine, local and landscape-level attributes influence nest box selection by wildlife can assist practitioners in refining nest box designs and placement in the field. We asked: Does entrance size, tree size and landscape context affect nest box occupancy? We monitored 144 nest boxes with six different entrance sizes (20, 35, 55, 75, 95 and 115mm diameter), secured to individual trees of three sizes (small 20–50cm DBH, medium 51–80cm and large >80cm) situated in four different landscape contexts with varying degrees of modification (reserves, pasture, urban parklands and urban built-up areas). We found that six common native and exotic species accounted for 89% of nest box occupancies. Entrance size had a significant effect on overall occupancy. Nest boxes with larger entrance sizes (115, 95, 75 and 55mm) were occupied more (⩾77% of nest boxes occupied) than nest boxes with smaller entrance sizes (35 and 20mm; ⩽45% of nest boxes occupied). Tree size and landscape context had no significant effect on overall occupancy. However, multinomial analysis revealed that entrance size and landscape context affected occupancy by common fauna (i.e. species that occupied ⩾5% of nest boxes). Nest boxes with small (20 and 35mm), intermediate (55 and 75mm) and large (95 and 115mm) entrance sizes were predominately occupied by the European honey bee Apis mellifera, common exotic (e.g. common myna Acridotheres tristis) and native birds (e.g. eastern rosella Platycercus eximius), and the common brushtail possum Trichosurus vulpecula, respectively. Nest boxes in reserves and pasture had near equal occupancy by common fauna while nest boxes in urban parklands and urban built-up areas were predominately occupied by the common brushtail possum and the European honey bee. Establishing nest boxes with different entrance sizes could maximise occupancy by a variety of common hollow-nesting species. Targeting occupancy by some species requires consideration of landscape context but not tree size. Nest boxes were predominately occupied by a few common native and exotic species, suggesting that nest boxes may not be highly effective management and biodiversity offset tools for rare and threatened taxa in modified landscapes. Management policies and practices aimed at avoiding the loss of large, hollow-bearing trees must be prioritised.

The aetiology of wobbly possum disease: Reproduction of the disease with purified nidovirus

The objective of this study was to investigate a role of a recently discovered marsupial nidovirus in the development of a neurological disease, termed wobbly possum disease (WPD), in the Australian brushtail possum (Trichosurus vulpecula). Four possums received 1mL of a standard inoculum that had been prepared from tissues of WPD-affected possums, 4 possums received 1.8mL (1×106 TCID50) of a cell lysate from inoculated cultures, and 4 possums received 1mL (×107 TCID50) of a purified WPD isolate. All but one possum that received infectious inocula developed neurological disease and histopathological lesions characteristic for WPD. High levels of viral RNA were detected in livers from all possums that received infectious inocula, but not from control possums. Altogether, our data provide strong experimental evidence for the causative involvement of WPD virus in development of a neurological disease in infected animals.

A modelling framework for predicting the optimal balance between control and surveillance effort in the local eradication of tuberculosis in New Zealand wildlife

Bovine tuberculosis (TB) impacts livestock farming in New Zealand, where the introduced marsupial brushtail possum (Trichosurus vulpecula) is the wildlife maintenance host for Mycobacterium bovis. New Zealand has implemented a campaign to control TB using a co-ordinated programme of livestock diagnostic testing and large-scale culling of possums, with the long-term aim of TB eradication. For management of the disease in wildlife, methods that can optimise the balance between control and surveillance effort will facilitate the objective of eradication on a fixed or limited budget. We modelled and compared management options to optimise the balance between the two activities necessary to achieve and verify eradication of TB from New Zealand wildlife: the number of lethal population control operations required to halt the M. bovis infection cycle in possums, and the subsequent surveillance effort needed to confidently declare TB freedom post-control. The approach considered the costs of control and surveillance, as well as the potential costs of re-control resulting from false declaration of TB freedom. The required years of surveillance decreased with increasing numbers of possum lethal control operations but the overall time to declare TB freedom depended on additional factors, such as the probability of freedom from disease after control and the probability of success of mop-up control, i.e. retroactive culling following detection of persistent disease in the residual possum population. The total expected cost was also dependent on a number of factors, many of which had wide cost ranges, suggesting that an optimal strategy is unlikely to be singular and fixed, but will likely vary for each different area being considered. Our approach provides a simple framework that considers the known and potential costs of possum control and TB surveillance, enabling managers to optimise the balance between these two activities to achieve and prove eradication of a wildlife disease, or the pest species that transmits it, in the most expedient and economic way. This cost- and risk-evaluation approach may be applicable to other wildlife disease problems where limited management funds exist.

A systematic approach to evaluating and ranking the relative animal welfare impacts of wildlife control methods: poisons used for lethal control of brushtail possums (Trichosurus vulpecula) in New Zealand

Context Control of unwanted wildlife (‘pest’ animals) is undertaken for conservation and economic reasons, and when such animals are considered a nuisance. Such control should be undertaken using approaches that minimise, as far as possible, detrimental impacts on the welfare of the animals. Using a scientific framework based on the Five Domains model, the relative welfare impacts of pest control methods can be compared across methods and pest species. Aims We demonstrate the application of a modified version of this framework to evaluate the relative impacts of seven Vertebrate Toxic Agents (VTAs) used to control brushtail possums (Trichosurus vulpecula) in New Zealand. The evaluation is used to produce a ranking of the seven VTAs based on their relative impacts on possum welfare. Methods Scientific literature describing mode of toxic action, specific effects in possums or other animals and reports from human poisonings was collated as reference material for a panel of six experts. The panel produced a median welfare impact score (‘none’ to ‘extreme’) for each of the Five Domains. The ‘Overall Grade’ (1 to 8) reflected the intensity and duration of all impacts of a VTA on possums. Key results All VTAs evaluated have at least moderate impacts on possum welfare, lasting for at least minutes. Cyanide was assessed as having the lowest welfare impacts (median grade 4), and cholecalciferol and the anticoagulants the highest impacts (7.5 to 8). Zinc phosphide was assigned an intermediate grade (6) with high confidence. While the overall impacts of sodium fluoroacetate (1080) and phosphorus were also assessed as intermediate (6), the panel’s confidence in these scores was low. Conclusions From an animal welfare perspective, anticoagulant poisons and cholecalciferol should be the least preferred options for controlling possums in New Zealand, as VTAs with less severe welfare impacts are available. Implications The results of such assessments allow animal welfare impacts to be integrated with other factors in wildlife management decision-making and policy development, and are thus useful for managers, researchers, regulators and operators. Evaluation of welfare impacts aligns with the goals and mandates of ethical wildlife control and may also be valuable in wider wildlife research and management activities.

Effective field-based methods to quantify personality in brushtail possums (Trichosurus vulpecula)

Context There is growing recognition of the importance of animal personality in wildlife ecology and management. Individuals that differ consistently in their behaviours from others of the same population are considered to exhibit different personalities. Personality can be easily quantified with repeat tests on animals held in captivity. However, captive-based tests may not always be possible for logistical reasons and tests conducted in captivity can alter naturally occurring behaviours. Development of methods to assess personality in the field over short-term capture is an important alternative to long-term captive tests. Aims To develop and refine field-based tests that can be used to easily define personality traits of wild common brushtail possum (Trichosurus vulpecula), eliminating the need to bring individuals into captivity for an extended period of time. Methods We developed a series of short-term capture protocols to quantify personality traits of the common brushtail possum in the field, using handling-bag tests, modified open-field tests, trap-behaviour tests and release tests. Key results Personality traits of brushtail possums could be measured in several different ways, but refining methods was crucial to reveal traits efficiently. Behaviours related to several personality traits (boldness, docility and activity/exploration) could be measured rapidly in the field with our methods, and were repeatable over time. Conclusions Rapid, reliable and easy-to-perform quantification of personality of brushtail possums in the field is possible. This may sometimes be the only available option, and has advantages over long captive trials in terms of animal welfare and cost. Implications The present study provides a baseline for future research on the personality of common brushtail possums and its application to management and control strategies for the species.

A review of biodiversity outcomes from possum-focused pest control in New Zealand

Worldwide, introduced vertebrate pests impact primary production, native biodiversity, and human health. In New Zealand, extensive pest control (~10 million ha) is undertaken to protect native biota and to prevent losses to the primary sector from wildlife vectors of bovine tuberculosis (TB), primarily possums (Trichosurus vulpecula). Control is conducted by TBfree New Zealand and by conservation agencies. Remote, forested terrain is treated using the toxin 1080 via aerial delivery in bait with a return time of ~5 years. Ground-based control is conducted annually using traps and/or poison bait. Possums are controlled to very low abundance by these operations. Aerial 1080 is effective against another forest-dwelling vertebrate pest, the ship rat (Rattus rattus). Possum control has reduced TB rates, but collateral benefits for native biodiversity have not been quantified, making it difficult to demonstrate a return on investment. We review information from 47 accounts of responses of native biota to possum control. Of these, 60% quantified responses to aerial 1080; the remainder were ground-based. Possum control benefited vegetation by increasing foliage and fruit production, and by reducing tree mortality. Controlling ship rats and possums together improved bird populations, but rats recovered rapidly and long-term outcomes for rat-vulnerable birds are unknown.Large-bodied invertebrates also benefited from extensive pest control. We conducted a meta-analysis of 84 response measures from 35 of these 47 studies in order to provide a quantitative assessment of these findings. The analysis demonstrated that both ground and aerial control of this invasive pest in New Zealand has provided substantial collateral benefits for native biota. Few studies have taken advantage of decades of extensive pest control in New Zealand to monitor ecosystem-level outcomes, which have received only short-term attention thus far. Non-treatment experimental controls and replicate sites that enable validated assessments of outcomes for native biota are vital. Future studies would benefit from a standardised set of biodiversity indicators from a range of taxonomic and functional groupings, and from standardising experimental designs so individual studies can contribute to future meta-analyses, to strengthen the evidence base for the impacts of invasive pests on native biota in New Zealand and worldwide.

Interactions between humans and urban-adapted marsupials on private properties in the greater Perth region

This study documents a range of interactions between humans and quenda (Isoodon obesulus) and brushtail possums (Trichosurus vulpecula) in urbanised Perth, Australia. These interactions are of veterinary public health significance. Findings suggest that public education is important to safeguard the health of both the marsupials and humans involved in such interactions.

A novel device for controlling brushtail possums (Trichosurus vulpecula)

A novel device for controlling brushtail possums (Trichosurus vulpecula)

Predicting survivors: animal temperament and translocation

Translocation is an important conservation management tool. However, not all individuals are equally suited to translocation, and temperament traits (e.g., boldness, reactivity, exploration, sociability, and aggression) are likely to influence survival in a new environment. A few empirical studies have examined the consequences of personality differences on captive-bred translocated animals, but this has not been done for wild-caught animals. We compared behavioral responses to trapping, processing, holding, and release for 56 wild common brushtail possums (Trichosurus vulpecula). Twenty individuals were captured twice, once to attach radio-tracking collars, the second time (2 weeks later) for the translocation. Consistency of behavioral responses was compared between capture events and radio-tracking allowed estimates of pretranslocation home range, rest site selection, and foraging behavior. Survivors (n = 10 survivors, 5 months later) were individuals showing the most fear or emotional reactivity during holding (less likely to have slept, eaten, defecated, or nested) and those that had the smallest home ranges and selected the safest den sites in their original habitat. Conversely, the greatest increase in body mass was recorded for individuals that had demonstrated unsafe behavior in their original habitat. To our knowledge, this is the first time this type of behavioral screening during handling and holding prior to release as part of a translocation has been undertaken. These methods have broad applicability for screening potential translocation candidates and are easily translated to a range of threatened and vulnerable animal species.

Common Mynas attack Common Brushtail Possums and nesting Southern Boobook, and diet of the nesting Boobooks

Over a 30-night period a Common Myna Acridotheres tristis was observed attacking Common Brushtail Possums Trichosurus vulpecula and harassing a female Southern Boobook Ninox boobook near her nest. One night a Myna that had been attacking Possums was chased by the male Boobook, which appeared to be chasing it as prey. We did not observe further attacks by Mynas after this night. Common Mynas were found in the dietary analysis for this pair of Boobooks.

Observations of mobbing and other agonistic responses to the Powerful Owl Ninox strenua

Mobbing is an anti-predator strategy in which prey animals, notably birds and mammals, aggravate a potential predator to either distract or drive them from the vicinity. The Powerful Owl Ninox strenua is a large forest owl endemic to eastern Australia that preys mainly on arboreal mammals and birds. We identified records of 30 species of birds and one mammal known to mob the Powerful Owl from scientific literature and unpublished studies. In our study in southern Sydney, Powerful Owls were most frequently mobbed by Noisy Miners Manorina melanocephala and Pied Currawongs Strepera graculina, followed by Grey Butcherbirds Cracticus torquatus and Australian Magpies Cracticus tibicen. We observed mobbing by three species of bird and one mammal that were not previously recorded as mobbing species, including agonistic responses by a Tawny Frogmouth Podargus strigoides and Common Brushtail Possum Trichosurus vulpecula during the time owls were active.