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The detection of avian viruses in wild populations has considerable conservation implications. For DNA-based studies, feathers may be a convenient sample type for virus screening and are, therefore, an increasingly common technique. This is despite recent concerns about DNA quality, ethics, and a paucity of data comparing the reliability and sensitivity of feather sampling to other common sample types such as blood. Alternatively, skeletal muscle tissue may offer a convenient sample to collect from dead birds, which may reveal viraemia. Here, we describe a probe-based quantitative real-time PCR for the relative quantification of beak and feather disease virus (BFDV), a pathogen of serious conservation concern for parrots globally. We used this method to test for BFDV in wild crimson rosellas (Platycercus elegans), and compared three different sample types. We detected BFDV in samples from 29 out of 84 individuals (34.5%). However, feather samples provided discordant results concerning virus presence when compared with muscle tissue and blood, and estimates of viral load varied somewhat between different sample types. This study provides evidence for widespread infection of BFDV in wild crimson rosellas, but highlights the importance of sample type when generating and interpreting qualitative and quantitative avian virus data.
Prescribed fires for fuel reduction affect wildlife in several ways. We observed a marked increase in superb lyrebird (Menura novaehollandiae) numbers after a controlled burn in Guy Fawkes River National Park, New South Wales, in April and May 2014. The fire occurred during the winter breeding season; however, congregations of males were often seen together in the burnt landscape, indicating an opportunistic prioritisation of foraging. The low-intensity fire cleared brush and low-level vegetation, thus decreasing foraging effort and potentially attracting the species despite the need to seek mating partners. Controlled burns therefore have the potential to attract superb lyrebirds immediately after fire due to ease of movement and foraging effort.
Daily torpor, a short-term reduction in body temperature and metabolism, is an energy-saving strategy that has been interpreted as an adaptation to unpredictable resource availability. However, the effect of food-supply variability on torpor, separately from consistent food restriction, remains largely unexamined. In this study, we investigated the effect of unpredictable food availability on torpor in stripe-faced dunnarts (Sminthopsis macroura). After a control period of ad libitum feeding, dunnarts were offered 65% of their average daily ad libitum intake over 31 days, either as a constant restriction (i.e. as equal amount of food offered each day) or as an unpredictable schedule of feed offered, varied daily as 0%, 30%, 60%, 100% or 130% of ad libitum. Both feeding groups had increased torpor-bout occurrences (as a proportion of all dunnarts on a given day) and torpor-bout frequency (average number of bouts each day) when on a restricted diet compared with ad libitum feeding, but torpor frequency did not differ between the consistently restricted and unpredictably restricted groups. Most importantly, torpor occurrence and daily bout frequency by the unpredictably restricted group appeared to change in direct association with the amount of food offered on each day; torpor frequency was higher on days of low food availability. Our data do not support the interpretation that torpor is a response to unpredictable food availability per se, but rather that torpor allowed a rapid adjustment of energy expenditure to manage daily fluctuations in food availability.
The control of foxes (Vulpes vulpes) is a key component of many fauna recovery programs in Australia. A question crucial to the success of these programs is how fox control influences feral cat abundance and subsequently affects predation upon native fauna. Historically, this question has been difficult to address because invasive predators are typically challenging to monitor. Here, non-invasive DNA analysis was used to determine the fate of radio-collared woylies (Bettongia penicillata) in two reserves in a mesic environment where foxes had been controlled intensively for over two decades. Woylie trap success had increased more than 20-fold after fox baiting commenced in the 1980s but decreased precipitously in 2000. Ninety-eight monitored woylies were killed between 2006 and 2009. DNA analysis of swabs taken from radio-collars and carcasses of these woylies indicated that predation by cats (Felis catus) caused most mortalities (65%) and was three times the fox predation rate (21%). Also, indices of cat abundance were higher in fox-baited sites where foxes were less abundant. Predation on woylies by cats was greater than previously recognised and, by implication, may significantly reduce the effectiveness of fox control programs throughout Australia. Integrated fox and cat control is essential to ensure the success of fauna recovery programs.
We determined preferences of the Pilliga mouse, Pseudomys pilligaensis, for habitat attributes (ground and vegetation cover) through phases of a population irruption, and characterised refuge sites used when environmental conditions were unfavourable. In general, P. pilligaensis preferred areas with substrate dominated by sand and shrubs rather than rock or litter. However, its habitat selection changed with phases of the irruption. In the Increase phase, it showed no strong habitat preferences, perhaps because the abundance of food (seeds) overrode preferences for more stable habitat values. Its sensitivity to habitat variables increased in the Peak phase. In the Low phase, mice preferred ground cover with higher proportions of sand and shrubs, and lower proportions of rock and litter. Regression analyses suggested that sandy substrate is the most important factor for the refuge habitat of P. pilligaensis, perhaps because a sandy surface can support more understorey shrubs which provide seeds and protection from predators, and provides sites for burrows. Judging from areas where P. pilligaensis was caught during the Low phase, water run-on areas could also characterise refuge habitats. However, further studies are needed to define the species’ refuge habitats fully.
Dolichogenidea tasmanica (Hymenoptera: Braconidae) is the most commonly reared parasitoid from larval light brown apple moth (LBAM), Epiphyas postvittana (Lepidoptera: Tortricidae), feeding on grapevines in Australia. In order to evaluate the efficiency of searching behaviour of D. tasmanica, a laboratory study was undertaken to determine how this wasp responds to the susceptible stages of larval LBAM. Observations of searching behaviour were made in a wind tunnel, which allowed the wasp to express its full range of behaviour. The behaviour of D. tasmanica and susceptibility of LBAM to parasitism varies significantly among instars. The wasp most readily parasitises newly hatched larvae, but can parasitise the first three of the six instars. The first instars cause less damage and also produce less faeces and silk than later instars, so they are associated with less volatile cues that may be detected by the parasitoid. Flight initiation to an infested leaf was lower in the presence of first instars compared with second and third instars. The flight duration was shortest when females were exposed to plants infested by third instars. An analysis of the sequence and timing of searching behaviour indicated that females respond differently to each of the instars of LBAM.
Hares were introduced into Australia early in the period of European settlement. This study examined historical issues of newspapers and other historical sources to ascertain the number of importations, the number of hares landed alive, their destinations, relevant habitat characteristics at the sites of the releases, and whether the propagules became established and spread. Forty shipments were identified, and one or more live hares were landed from 27 of those shipments, totalling ∼86 live hares, and resulted in the establishment of 10 populations of hares. The climate and the grasses at the known release sites were suitable for Lepus europaeus and predators were rigorously suppressed, which, acting together with the wealth, power, influence, and determination of the proponents of the importations, made establishment of hares in Australia almost certain. However, 11 of the hares landed alive were almost certainly L. nigricollis, and the fates of seven of those hares are not known. There are populations of hares in Australia at sites suited to L. nigricollis but not L. europaeus on the basis of climate and availability of C4 grass types, and the taxonomic status of those hares should be examined.
Sandalwood (Santalum spicatum) has been almost entirely removed from the agricultural regions of Australia. Remaining stands, in the rangelands of Western Australia, are characterised by poor recruitment due to grazing of seedlings and lack of seed dispersal. The aim of this study was to determine whether reintroduced burrowing bettongs (Bettongia lesueur) would disperse sandalwood seed as part of a rangeland-restoration project. The bettongs removed most of the experimental seed within two days, scatter hoarded and cached seed near potential host plants. No broad conclusions can be made from this short-term study, but it has established that burrowing bettongs carry out an important ecosystem service, because moving sandalwood seeds away from the parent plant and close to a host plant is the primary means of promoting recruitment.
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