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Litoria cyclorhyncha (Hylidae) is native to southern Western Australia, but a naturalised population has established on the Eyre Peninsula, South Australia. We investigated the diet of this exotic population to assess potential impacts on biodiversity and ecosystems. Seventy-six frogs were collected from three different habitats and their diet items assigned to parataxonomic units (PU) within orders. Stomach contents were diverse, containing 467 prey items from 19 orders and 135 PU, with extrapolation suggesting a diet of ∼200 PU. Shannon diversity estimates of prey items consumed produced different rankings for the three habitats at the PU and order level. Therefore, estimates at the order level may not be representative of the actual diversity of prey items. L. cyclorhyncha consumed mainly arthropods and low numbers of conspecific young frogs, geckos and a juvenile house mouse. This generalist, indiscriminate predatory diet is similar to that of other hylids and implies that the species poses a risk to native biodiversity and ecosystem processes by predation and competition. Therefore, further spread of this species needs to be prevented. Our findings can inform effective policies and management actions to mitigate future impacts of L. cyclorhyncha.
Dual-energy X-ray absorptiometry (DXA) is a non-invasive technology for measurement of body composition that requires validation against reference methods when applied to a new species. The aim of this work was to validate DXA for the assessment of body composition of the echidna. Body composition was determined in the short-beaked echidna (Tachyglossus aculeatus aculeatus) using a Norland XR36 DXA scanner and validated by proximate chemical analysis for dry matter, ash, crude fat (FM) and protein (as 6.25 × N) and bone mineral content (BMC). Echidnas were opportunistically obtained as ‘road kill’. Body composition data were compared between techniques by correlation and limits of agreement (LOA) analyses. Twenty-eight echidnas (11 males, 13 females, 4 not determined), weighing 520–5517 g, underwent analyses. Mean FM was 489.9 ± 439.5 g and 448.5 ± 337.5 g, lean mass was 2276.0 ± 1021.4 g and 2256.0 ± 1026.0 g, fat-free mass was 2356.3 ± 1055.1 g and 2389.5 ± 1081.1 g and BMC was 80.3 ± 39.5 g and 79.9 ± 42.4 g by DXA and chemical analysis, respectively. The two methods were highly correlated (0.84 to 0.99) and not significantly different, although LOA were large. DXA has the potential to be used to assess body composition of echidnas although further work is required to improve accuracy of measurement.
The diet of the European red fox (Vulpes vulpes) was investigated through analysis of 1185 scats collected between 2010 and 2014 from coastal south-east Queensland, Australia. By both frequency of occurrence and volume, its diet was dominated by terrestrial arthropods, marine arthropods, vegetation and birds, although the remains of the short-tailed shearwater (Ardenna tenuirostris) consumed as carrion dominated the latter. Terrestrial arthropods, primarily insects of the order Coleoptera, were eaten all year (61% frequency of occurrence, FO) but varied seasonally (35–67%FO), mostly due to the consumption of large numbers of Christmas beetles (Anoplognathus spp.) in the summer months. Marine arthropods consisted almost entirely of ghost crabs (Ocypode spp.) and seasonal variation in consumption was evident (33–72%FO) and likely correlated with ghost crab abundance. Fruit and berries were an important food item for foxes all year but also varied seasonally (30–65%FO). The opportunistic diet of this fox population is discussed in the context of dietary differences, but common opportunism, reported in other Australian and overseas studies.
The abilities of freshwater turtles to control their body temperatures by behavioural means have implications for activity, food ingestion and digestion, growth, reproduction and potential responses to climate change. I compared various forms of basking in nature, and responses to aquatic and aerial photothermal gradients in the laboratory, among three species of Australian chelid turtles: Chelodina expansa, C. longicollis and Emydura macquarii. Proclivity for behavioural thermoregulation varied substantially among these species, being highest in C. longicollis and lowest in C. expansa. However, C. expansa had a thermophilic response to feeding. For C. longicollis and E. macquarii, behavioural thermoregulation may enhance colonisation of more southerly latitudes or higher elevations as climatic warming proceeds. However, increasing air temperatures may pose a hazard to turtles dispersing or sheltering terrestrially (for example, when water bodies dry during drought). C. longicollis appears the best placed of the three species to avoid this hazard through its abilities to thermoregulate behaviourally and to aestivate in terrestrial microenvironments that are buffered against temperature extremes.
The presence of nymphs of the introduced pentastomid parasite Linguatula serrata is verified in a native Australian animal, the red-necked wallaby (Notamacropus rufogriseus), for the first time. Morphological and genetic analyses confirmed the species identification, with a 100% genetic match to samples collected from various introduced animals from the same location in Kosciuszko National Park. Previous reports of pentastomids, including possible Linguatula sp. infections, in native animals are discussed. More research is required to confirm the validity of these reports.
Plant secondary metabolites can affect insect feeding but responses are species-specific. Sideroxylonal-A (a formylated phloroglucinol) has been shown to inhibit feeding in several vertebrate and invertebrate herbivores. To investigate whether sideroxylonal-A affected feeding in sawfly larvae, Perga affinis affinis, we fed larvae eucalypt leaves containing various concentrations of sideroxylonal-A, and measured frass production as an indicator of consumption. We found that: (1) at least 80% of the sideroxylonal-A ingested by larvae was stored in the diverticulum; (2) less than 1% was excreted in frass; (3) feeding was unaffected by the concentration of sideroxylonal-A; and (4) larvae produced more frass on natal host leaves than on non-natal host leaves.
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