Wallabia Research Articles

Habitat-specific and season-specific faecal pellet decay rates for five mammalian herbivores in south-eastern Australia

The accuracy of population abundance estimates of mammalian herbivores from faecal pellet counts is potentially affected by pellet decay. We collected fresh pellet groups from hog deer (Axis porcinus), European rabbit (Oryctolagus cuniculus), eastern grey kangaroo (Macropus giganteus), swamp wallaby (Wallabia bicolor) and common wombat (Vombatus ursinus) (n = 300 per species) at Wilsons Promontory National Park, Victoria, Australia. We deposited five pellet groups per species per month within each of five vegetation types in the park, then monitored pellet group decay over 24 months. We demonstrate that age estimation of pellet groups was inaccurate and is unlikely to improve the efficiency of pellet counts. We present habitat- and species-specific estimates of pellet and pellet group decay using two measures: decay rate (the proportion of pellets surviving per unit of time); and mean time to decay. We explain how our data can be used to optimise faecal pellet count design, and to improve the accuracy of both indices and estimates of abundance from pellet counts. The variability observed in the decay of pellet groups among vegetation types, and for species among seasons, suggests that caution should be used if applying pellet decay rates over long time-frames or to locations with differing environmental conditions.

Do body size, diet type or residence time explain habitat use in a vertebrate herbivore community?

Many theories attempt to explain patterns of community organisation among large herbivores. We explored the role of body size, diet type and residence time on habitat use in a community comprising four metatherians (western grey kangaroo, Macropus fuliginosus; eastern grey kangaroo, M. giganteus; red-necked wallaby, Notamacropus rufogriseus; swamp wallaby, Wallabia bicolor) and two eutherians (red deer, Cervus elaphus; European rabbit, Oryctolagus cuniculus) in south-eastern Australia. We used camera traps to estimate habitat occupancy, quantified habitat specialisation using relative entropy, and ran regressions using percentage grass consumed, log(mass) and log(time at site) as predictor variables and relative entropy as the response. If body size influenced habitat use, we predicted smaller species would occupy fewer habitats. If diet type influenced habitat use, we predicted intermediate feeders would use more habitats. If the time that a species had been present at a site predicted community organisation, newer species would use more habitats. None of these theories explained habitat use in our community. Red deer used a narrower range of habitats than expected, perhaps due to the poor suitability of habitats available in the Grampians. While interactions between our hypotheses are likely to be important, the body size model deserves further attention in this community.

Ecological specialisation in habitat selection within a macropodid herbivore guild

Specialist species show stronger resource selection, narrower niches and lower niche overlap than generalist species. We examined ecological specialisation with respect to habitat selection in a macropodid community comprising the western grey kangaroo Macropus fuliginosus, red-necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor in the Grampians National Park, Victoria, Australia. We used radio tracking to quantify habitat selection. We predicted that because the fitness benefits of generalisation and specialisation differ, there would be a mix of generalised and specialised species in our community. As all three macropodid species show marked sexual dimorphism, we also expected that they would show sex-based specialisation. Finally, because many large herbivores select different habitats for foraging and resting, we predicted that our species would specialise on a subset of their overall selected habitat based on activity period (diurnal or nocturnal). All three species specialised on the available resources to some degree. Western grey kangaroos were specialists, at least during the active period. Niche data for the two wallaby species were harder to interpret so we could not determine their degree of specialisation. Within species, we found no evidence of sex-based specialisation. However, we found clear evidence of specialisation by activity period in western grey kangaroos and red-necked wallabies, but not in swamp wallabies. The strength of behavioural decisions made during the active period in influencing specialisation points to the likelihood that bottom-up processes regulate this community.

Oils ain’t oils: can truffle-infused food additives improve detection of rare and cryptic mycophagous mammals?

We tested whether an artificial food additive, truffle oil, improved detection of mycophagous mammals when added to a standard bait type of peanut butter and rolled oats used with camera traps. Sixteen mammalian taxa were subsequently recorded, the most common being antechinus, bush rat (Rattus fuscipes), swamp wallaby (Wallabia bicolor) and long-nosed bandicoot (Perameles nasuta) as well as the long-nosed potoroo (Potorous tridactylus) and southern brown bandicoot (Isoodon obesulus). The only species for which detection rate was improved by the addition of truffle oil to standard bait was the ringtail possum (Pseudocheirus peregrinus), a species that has never been recorded eating fungi. In contrast, the total number of detections of all species at any given site was significantly higher, on average, using standard bait without truffle oil, as was the average number of detections of the partially mycophagous bush rat. Time to first detection of bush rats and swamp wallabies was significantly shorter using the standard bait type, compared with one with truffle oil added. Overall, the use of the truffle oil additive did not improve the chance or rate of detecting mycophagous mammals. To maximise the number of detections of mammals at camera traps the use of a standard bait type of peanut butter and rolled oats is recommended.

Fine-Scale Habitat Heterogeneity Influences Occupancy in Terrestrial Mammals in a Temperate Region of Australia.

Vegetation heterogeneity is an inherent feature of most ecosystems, characterises the structure of habitat, and is considered an important driver of species distribution patterns. However, quantifying fine-scale heterogeneity of vegetation cover can be time consuming, and therefore it is seldom measured. Here, we determine if heterogeneity is worthwhile measuring, in addition to the amount of cover, when examining species distribution patterns. Further, we investigated the effect of the surrounding landscape heterogeneity on species occupancy. We tested the effect of cover and heterogeneity of trees and shrubs, and the context of the surrounding landscape (number of habitats and distance to an ecotone) on site occupancy of three mammal species (the black wallaby [Wallabia bicolor], the long-nosed bandicoot [Perameles nasuta], and the bush rat [Rattus fuscipes]) within a naturally heterogeneous landscape in a temperate region of Australia. We found that fine-scale heterogeneity of vegetation attributes is an important driver of mammal occurrence of two of these species. Further, we found that, although all three species responded positively to vegetation heterogeneity, different mammals vary in their response to different types of vegetation heterogeneity measurement. For example, the black wallaby responded to the proximity of an ecotone, and the bush rat and the long-nosed bandicoot responded to fine-scale heterogeneity of small tree cover, whereas none of the mammals responded to broad scale heterogeneity (i.e., the number of habitat types). Our results highlight the influence of methodological decisions, such as how heterogeneity vegetation is measured, in quantifying species responses to habitat structures. The findings confirm the importance of choosing meaningful heterogeneity measures when modelling the factors influencing occupancy of the species of interest.

Comparative finite element analysis of the cranial performance of four herbivorous marsupials.

Marsupial herbivores exhibit a wide variety of skull shapes and sizes to exploit different ecological niches. Several studies on teeth, dentaries, and jaw adductor muscles indicate that marsupial herbivores exhibit different specializations for grazing and browsing. No studies, however, have examined the skulls of marsupial herbivores to determine the relationship between stress and strain, and the evolution of skull shape. The relationship between skull morphology, biomechanical performance, and diet was tested by applying the finite element method to the skulls of four marsupial herbivores: the common wombat (Vombatus ursinus), koala (Phascolarctos cinereus), swamp wallaby (Wallabia bicolor), and red kangaroo (Macropus rufus). It was hypothesized that grazers, requiring stronger skulls to process tougher food, would have higher biomechanical performance than browsers. This was true when comparing the koala and wallaby (browsers) to the wombat (a grazer). The cranial model of the wombat resulted in low stress and high mechanical efficiency in relation to a robust skull capable of generating high bite forces. However, the kangaroo, also a grazer, has evolved a very different strategy to process tough food. The cranium is much more gracile and has higher stress and lower mechanical efficiency, but they adopt a different method of processing food by having a curved tooth row to concentrate force in a smaller area and molar progression to remove worn teeth from the tooth row. Therefore, the position of the bite is crucial for the structural performance of the kangaroo skull, while it is not for the wombat which process food along the entire tooth row. In accordance with previous studies, the results from this study show the mammalian skull is optimized to resist forces generated during feeding. However, other factors, including the lifestyle of the animal and its environment, also affect selection for skull morphology to meet multiple functional demands.

Dental fluorosis and skeletal fluoride content as biomarkers of excess fluoride exposure in marsupials

Particulate and gaseous fluoride emissions contaminate vegetation near fluoride-emitting industries, potentially impacting herbivorous wildlife in neighboring areas. Dental fluorosis has been associated with consumption of fluoride-contaminated foliage by juvenile livestock and wildlife in Europe and North America. For the first time, we explored the epidemiology and comparative pathology of dental fluorosis in Australian marsupials residing near an aluminium smelter. Six species (Macropus giganteus, Macropus rufogriseus, Wallabia bicolor, Phascolarctos cinereus, Trichosurus vulpecula, Pseudocheirus peregrinus) demonstrated significantly higher bone fluoride levels in the high (n=161 individuals), compared to the low (n=67 individuals), fluoride areas (p<0.001). Necropsy examinations of all six species from the high-fluoride area near the smelter revealed dental lesions considered characteristic of dental fluorosis in eutherian mammals. Within the high-fluoride area, 67% of individuals across the six species showed dental enamel lesions, compared to 3% in the low-fluoride areas. Molars that erupted before weaning were significantly less likely to display pathological lesions than those developing later, and molars in the posterior portion of the dental arcade were more severely fluorotic than anterior molars in all six species. The severity of dental lesions was positively associated with increasing bone fluoride levels in all species, revealing a potential biomarker of excess fluoride exposure.

Herbivore search behaviour drives associational plant refuge

Herbivore foraging decisions leading to consumption of a plant are complex and multi-faceted, shaped both by the plant itself and by its neighbours. Associational plant refuge arises when neighbours reduce focal plant susceptibility to herbivory. The specific foraging behaviours generating refuge patterns have rarely been examined in free-ranging systems, yet these are key to understanding why such refuge works or fails. We aimed to integrate herbivore foraging and associational plant refuge theories by linking foraging decisions directly to browsing outcomes on focal plants and their neighbours. We tested whether obstructive, unpalatable neighbours reduce the number of patch visits and/or interrupt searching, leading to associational refuge of focal plants. We compared visits by and behaviours of free-ranging mammalian browsers, swamp wallabies (Wallabia bicolor), in control and manipulated plant patches using cameras. Patches (7 m2) comprised a central focal plant (palatable native tree seedling, Eucalyptus pilularis) with neighbours of either existing or manipulated vegetation (unpalatable native daisy, Coronidium elatum). Wallabies made fewer visits to control than manipulated patches, but always browsed the focal plant during the first visit to a control patch. In contrast, wallabies often visited manipulated patches multiple times before browsing the focal plant. These ‘futile’ visits were both shorter and involved less searching time than visits when the focal plant was browsed. Focal plants escaped browsing for longer in manipulated than in control patches, and although none had escaped browsing after one year, survival was significantly greater in manipulated patches. We demonstrate that reduced investment in searching during visits to manipulated patches drove the associational plant refuge, but this refuge was eventually surmountable. Understanding the behaviours underpinning refuges allows better prediction of outcomes, and explains why refuge can collapse. By shaping foraging behaviour in patches, neighbouring vegetation can increase the probability that palatable plants persist despite high herbivore pressure.

Interspecific and geographic variation in the diets of sympatric carnivores: dingoes/wild dogs and red foxes in south-eastern Australia.

Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna. We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia. The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size. The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus). Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox. The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability. We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.

Shrub expansion alters forest structure but has little impact on native mammal occurrence

AbstractThe expansion (or encroachment) of shrubs in forests and woodlands is generally considered a serious threat to biodiversity. The effects of shrub expansion on forest fauna, however, are poorly understood and likely to depend on the availability of key resources in shrub‐encroached forest. Coranderrk Bushland, like many conservation reserves in south‐eastern Australia, is considered threatened by the spread of an indigenous shrub. We investigated the associations between cover of Yarra burgan (Kunzea leptospermoides (Myrtaceae)), vegetation structure and the occurrence of terrestrial native mammals within the reserve, basing our predictions on prior knowledge of burgan growth habits and fauna habitat preferences. We quantified burgan cover and other potentially important habitat attributes using structure surveys, and used motion‐sensing cameras to detect terrestrial mammals. Dense burgan cover was associated with less grass, a sparser understorey, and more cryptogams, dead trees and coarse woody debris. However, there was no evidence that these changes negatively affected native mammals: burgan cover had little influence on the occurrence of any species except swamp wallabies (Wallabia bicolor), which occurred in all areas of the reserve but shifted from sites with high burgan cover during the day to sites with low cover at night. Our findings contrast with those from grassland shrub‐expansion studies, where fauna generally show strong responses to shrub cover. The effects of shrub expansion on forest fauna may be mitigated by the greater pre‐existing structural diversity in forests or the longer time required for structural changes to be fully realized. The large quantities of dead wood in areas with high shrub cover may also provide compensatory resources for small mammals, while the proximity to un‐encroached areas may enable large herbivores to move between dense shelter and forage. Shrub‐encroached forests clearly provide resources for some native fauna, and management strategies need to consider the potential impacts of shrub removal on these taxa.

Associational refuge in practice: can existing vegetation facilitate woodland restoration?

Herbivores can dramatically diminish revegetation success, but associational refuge theory predicts that neighbouring plants could hinder browsing of planted seedlings. The key to strategic restoration using associational refuge is to define which patch variables are effective against the appropriate herbivores, at multiple scales, and to understand which stages of the foraging process these variables disrupt. Our study aimed to test the capacity of existing vegetation to act as associational refuge for planted seedlings by affecting search, detection and consumption decisions, and more generally influence herbivore foraging patterns. We conducted a field trial with free‐ranging, mammalian herbivores and nursery‐raised, native tree seedlings. We quantified seedling browsing damage over time in relation to a suite of existing patch variables at two spatial scales (100 m2 and 4 m2). After two months, 78% of seedlings were browsed, suffering mean foliage loss of 90.5%. Focal seedlings were almost exclusively consumed by swamp wallabies Wallabia bicolor, an abundant generalist browser. Once a swamp wallaby investigated a seedling, the probability of consumption was high (86%). At the large scale, browsing of seedlings was delayed in patches with lower canopy cover and fewer browsed plant species. Seedlings in fern‐dominated patches escaped browsing for longer than those in grass‐dominated patches. At the small scale, browsing was delayed with higher cover of understorey vegetation. Associational refuge was provided by vegetation with characteristics, and at spatial scales, consistent with disrupted search and detection of focal seedlings by herbivores. Thus strategic placement of seedlings in existing vegetation – based on understanding which herbivore species is responsible and how it responds to vegetation – can take advantage of associational refuge during restoration. However, given rapid seedling detection by herbivores, associational refuge may be inadequate in the long‐term under high browsing pressure unless high absolute numbers of seedlings are planted among refuge.

Genetic variation within and among species of Cloacina (Strongyloidea: Cloacinine) from the swamp wallaby, Wallabia bicolor (Marsupialia: Macropodidae)

This study examined genetic variation within and among species of Cloacina found in the swamp wallaby (Wallabia bicolor) collected at different localities along the eastern coast of Australia, and evaluated geographical distance as a potential driver for genetic variation. The first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of the nuclear ribosomal DNA were used to characterize individuals of 11 morphospecies of Cloacina that parasitize W. bicolor. The results of the molecular analyses revealed multiple genotypes for the nine morphospecies of Cloacina (i.e. Cloacina annulata, Cloacina edwardsi, Cloacina eos, Cloacina gallardi, Cloacina mawsonae, Cloacina papillata, Cloacina papillatissima, Cloacina pollux, and Cloacina wallabiae) for which multiple individuals were available for analysis. However, phylogenetic analyses of the sequence data revealed that for each morphospecies, there was no subdivision of individuals into distinct clades based on geographical region from which they were collected. Additional studies are needed to determine the drivers of genetic variation in cloacinid nematodes, and hence increase our understanding of the diversity of parasitic nematodes in macropodid marsupials.

Quantifying the response of free-ranging mammalian herbivores to the interplay between plant defense and nutrient concentrations.

While trying to achieve their nutritional requirements, foraging herbivores face the costs of plant defenses, such as toxins. Teasing apart the costs and benefits of various chemical constituents in plants is difficult because their chemical defenses and nutrient concentrations often co-vary. We used an approach derived from predator-prey studies to quantitatively compare the foraging response of a free-ranging mammalian herbivore, the swamp wallaby (Wallabia bicolor), through three feeding trials with artificial diets that differed in their concentrations of (1) the terpene 1,8-cineole, (2) primary constituents (including nitrogen and fiber), and (3) both the terpene and the primary constituents. Applying the giving-up density (GUD) framework, we demonstrated that the foraging cost of food patches increases with higher dietary cineole concentration and decreases with higher dietary nutrient concentration. The effect of combined differences in nutrients and cineole concentrations on GUD was interactive, and high nutrient food required more cineole to achieve the same patch value as low nutrient food. Our results indicate that swamp wallabies equate low nutrient, poorly defended food with high nutrient, highly defended food, providing two contrasting diets with similar cost-benefit outcomes. This behavior suggests that equal concentrations of chemical defenses provide nutrient-poor plants with relatively greater protection as nutrient-rich plants. Nutrient-rich plants may therefore face the exacerbated problem of being preferred by herbivores and therefore need to produce more defense compounds to achieve the same level of defense as nutrient-poor plants. Our findings help explain the difference in anti-herbivore strategy of nutrient-poor and rich plants, i.e., tolerance versus defense.

Inter‐ and intraspecific effects of body size on habitat use among sexually‐dimorphic macropodids

Body size affects key life‐history parameters including dietary requirements and predation risk. We examined these effects on diel habitat use in a community of three sexually‐dimorphic macropodid marsupial species: western grey kangaroo Macropus fuliginosus, red‐necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor. In particular, our study seeks evidence of these effects operating concurrently at the intra‐ and interspecific levels. We used radio‐tracking to quantify habitat use and characterised each used location by recording the cover of plant functional groups and the presence of plant species. During nocturnal foraging periods we predicted that smaller animals (between and within species) should use habitats with higher‐quality forage, which is often less abundant, than larger animals, as metabolic demand scales with body size. During diurnal resting periods we predicted that smaller animals (between and within species), being more vulnerable to predation, should use greater concealment cover than larger animals. Western grey kangaroos and swamp wallabies behaved as predicted during foraging periods, but red‐necked wallabies did not, using more open, poorer‐quality habitats than expected. Only western grey kangaroos showed a within‐species effect on habitat use: the relatively smaller females foraged in higher‐quality patches. Habitats used by animals during the resting period generally offered greater concealment cover than those used during the foraging period, but there were no clear body size effects on the density of vegetation used. In our system, body size alone could not explain all of the observed patterns, suggesting that there may also be individual differences in habitat requirements influenced by factors such as reproductive costs, predation risk and social facilitation.

New Species of Cloacina Von Linstow, 1898 (Nematoda: Strongylida) from the Swamp Wallaby, Wallabia Bicolor (Desmarest, 1804) (Marsupialia)

Although the principal species of the parasitic nematode genus Cloacina von Linstow, 1898 found in the stomach of the swamp wallaby, Wallabia bicolor (Desmarest, 1804) (Marsupialia) are relatively well established, continuing collections from this host have led to the finding of additional new species often with restricted geographical distributions or occurring rarely in the host. Three new species are described and an additional five undescribed species are identified which cannot be named due to lack of specimens. The three new species are C. aethra sp. nov. from Victoria, C. galatea sp nov. from Queensland and C. anthea sp. nov. from both Victoria and Queensland.

Does diet constrain the occupation of high elevations by macropods? A comparison between Macropus rufogriseus and Wallabia bicolor

The ability to utilise a diet of shrubs or trees is key to the survival of herbivores in deep snow. However, reduction in snow depth with climate change may allow herbivores into higher elevations where herbfields are dominant. Wallabia bicolor occurs above the winter snowline of the Snowy Mountains in the subalpine zone, whereas Macropus rufogriseus, does not although it is present in alpine Tasmania. The winter diet of W. bicolor in the Snowy Mountains consisted of shrubs, trees, and herbs. With &gt;60% of food sources (shrubs and trees) available above the snow, the change from occupation of habitat below the winter snowline to above requires little change in its diet. Consumption of shrubs, forbs and monocots by M. rufogriseus was similar between the Snowy Mountains and alpine Tasmania. M. rufogriseus includes a high proportion of shrubs in its diet; however, it may be excluded from snow-covered habitat due to a lesser ability to utilise poor-quality browse. Globally, migratory herbivores respond to deep snow with seasonal movements. However, W. bicolor and M. rufogriseus are not migratory and can only occupy higher elevations of the Snowy Mountains as snow depth and duration diminish. Because they do not currently occupy the alpine zone and the vegetation has not evolved to accommodate their presence, their impact on alpine vegetation is likely to be greater than migratory alpine grazers/browsers.

Estimations of Species Richness in The Complex Communities of Nematode Parasites Found in The Stomachs of Kangaroos and Wallabies (Family Macropodidae)

Kangaroos and wallabies harbour a diverse array of strongyloid nematodes in their sacculated forestomachs. Determining the number of nematode species present in complex communities such as these can be technically difficult due to the large size of the host organ, the large numbers of nematodes and the large number of closely related nematode species. This problem was investigated using species accumulation methods in 16 eastern grey kangaroos (Macropus giganteus), 15 red-necked wallabies (Macropus rufogriseus) and 6 swamp wallabies (Wallabia bicolor). Nematodes from a subsample of known size were identified individually to species and the number of nematodes which needed to be examined before all of the species in the subsample were found was determined. In M. giganteus (mean worm burden 20,500), between 27 and 92 (mean 57) nematodes had to be examined before all (13) species were recovered. In M. rufogriseus (mean worm burden 60,600), an examination of between 16 and 178 (mean 57) nematodes recovered all (8) species while in W. bicolor (mean worm burden 16,300), 16–196 (mean 67) nematodes needed to be examined to recover all (15) species present. It was concluded that examination of samples of 200 nematodes from each animal would have been sufficient to identify all parasite species present.

Roles of the volatile terpene, 1,8-cineole, in plant–herbivore interactions: a foraging odor cue as well as a toxin?

Olfaction is an important sense for many animals, yet its role in foraging by herbivores is poorly known. Many plants contain volatile compounds, such as terpenes, that are not only volatile but can be toxic if ingested. Volatile terpenes can be used by herbivores to assess leaf quality, but there is little evidence for whether they are also used as a searching cue. We applied the giving-up density (GUD) framework to examine fine-scale foraging by two free-ranging mammalian herbivores, the brush-tail possum (Trichosurus vulpecula) and the swamp wallaby (Wallabia bicolor), using patches with food and an inedible matrix that varied in content of a volatile terpene, 1,8-cineole. We tested the effect of (1) increasing dietary cineole concentration, and (2) masking the food odor by adding cineole to the inedible matrix, thus overriding the smell released by the diet. In both species GUD was affected by dietary cineole; a high cineole concentration raised GUD, consistent with its role as a toxin. There was a significant effect of masking on GUD for wallabies but not for possums, suggesting that odor was an important foraging cue at the feeding patch only for the former. Differences in ecological niche and diet may explain this pattern. We suggest that herbivores, such as the swamp wallaby, opportunistically eavesdrop on plant volatiles, i.e., take advantage of the signal proffered for a different function. The cost of this eavesdropping for plants, however, is presumably counteracted by other ecological benefits of these volatiles, including a reduction in leaf consumption as a function of toxicity.

Camera traps provide insight into factors influencing trap success of the swamp wallaby, Wallabia bicolor

Trapping programs for mammals often have low capture success, which is known to be influenced by a range of environmental factors, in addition to aspects of the traps themselves. However, the behavioural responses to traps by the target species are largely unknown. We simultaneously set camera traps and soft-walled double-layered traps for swamp wallabies, Wallabia bicolor, and used images from the camera traps to investigate responses by the target species. Wallabies mostly visited traps after sunset, with the number of visits declining steadily through the night. Visits to traps were more frequent during crescent and new moon phases and when the moon was set. In the majority (59%) of these visits, wallabies did not enter the traps. In some cases wallabies consumed only the bait outside the trap, or the trap door had been closed, usually by other swamp wallabies or bobucks, Trichosurus cunninghami, but in many cases (28% of visits) we could not discern why wallabies failed to enter. When wallabies did enter traps, just 14% of visits resulted in successful capture, with non-captures mainly occurring because wallabies reached in to obtain bait without triggering the trap.

Retrospective study of oral necrobacillosis in 54 swamp wallabies

Oral necrobacillosis (lumpy jaw) is known as one of the most common and significant diseases in captive macropods (Vogelnest and Portas 2008). The most important pathogen is the anaerobic bacteria, Fusobacterium necrophorum (Samuel 1983). Many studies have shown dental calculus as one of the risk factors for oral necrobacillosis, oral injury, feed contaminated with faeces, adverse environmental conditions, and molar exfoliation (Butler 1981, Oliphant and others 1984, Vogelnest and Portas 2008). In the present study, we conducted a retrospective study to reveal recurrence and evaluate the risk factors in swamp wallabies that presented with oral necrobacillosis. We showed that oral necrobacillosis recurred in all cases after apparent complete recovery, and that advanced age and cold weather were the contributing risk factors. Seventy-five swamp wallabies were housed at the Nogeyama Zoological Gardens from 1987 to 2011. For this retrospective study, we selected 54 individuals for which clinical records had been maintained from birth to death. The average age at the onset of the first lesion was examined. Further, the number of diseased individuals and the rate of diseased swamp wallabies were counted and calculated, respectively, at each age. The location(s) and number of lesion(s) were counted and analysed in each month, which also included recurrence cases. The average temperature of …