Matthew C. McDowell

The status of non-volant mammals along a rainfall gradient in the south-west Kimberley, Western Australia

To assess the current status of mammals in relation to mean annual rainfall and to improve knowledge of the original mammalian assemblages in tropical Western Australia, extant terrestrial mammals and subfossil mammalian remains were sought along a rainfall gradient in two parallel ranges in the Kimberley, Western Australia. As expected, extant mammal species richness decreased with decreasing rainfall. Data from other studies in higher-rainfall areas complemented this conclusion and a parallel decline in trap success implied an overall decline in abundance, although numbers of two rodents (Rattus tunneyi and Zyzomys argurus) were highly variable. Small rodents were rare. Subfossil deposits were biased by accumulation processes, with most attributable to tytonid owls. They largely consisted of rodent and, to a lesser extent, small dasyurid bones and there was a high level of consistency in the proportional composition of many common species across the rainfall gradient. Most deposits appear to predate the introduction of stock in the 1880s and some may be much older. All species persist in the study area except two Notomys spp. and three Pseudomys spp. Both the Notomys and one Pseudomys are apparently undescribed, extinct species. However, there were marked ratio differences between subfossil and modern assemblages. Although specimens of species larger than those taken by tytonid owls were scarce, their occurrences were broadly consistent with the modern understanding of distributions.

LAST RECORDED EVIDENCE FOR MEGAFAUNA AT WET CAVE, NARACOORTE, SOUTH AUSTRALIA 45,000 YEARS AGO

Over 85 percent of Australian terrestrial vertebrate genera with a body mass greater than 44 kg became extinct during the late Pleistocene. These included all marsupials exceeding 100 kg (1 9 species) and 22 of the 38 species between 10 and 100 kg. Dwarfing occurred in many other species (Flannery 1990; Miller et al. 1999). The larger of these extinct animals have been categorised as megafauna.

Natural Resource Management implications of the pre-European non-volant mammal fauna of the southern tip of Eyre Peninsula, South Australia

Sinkholes and coastal caves located in, around and between the Coffin Bay and Lincoln National Parks were surveyed for pre-European fossils, which were collected from or just below the sediment surface. Twenty-four pre-European fossil samples, including eight already in the collections of the South Australian Museum, were analysed and 25 native and five introduced species of non-volant mammal were identified. Native and introduced species were often found together, indicating that the sites have accumulated mammal remains in both pre- and post-European times. Only four of the non-volant native mammals recovered are known to be extant in the study area today: Lasiorhinus latifrons, Macropus fuliginosus, Cercartetus concinnus and Rattus fuscipes. In contrast, 20 native species recorded have been extirpated and one (Potorous platyops) is now extinct. C. concinnus was recorded from only one of the fossil assemblages but is known to be widespread in the study area today. This may indicate recent vegetation change related to European land management practices and have implications for natural resource management in the area.

The effects of drought on prey selection of the barn owl (Tyto alba) in the Strzelecki Regional Reserve, north-eastern South Australia

Changes in the diet of the barn owl (Tyto alba) were determined by analysing 619 egested pellets collected in eight samples over 12 months from a roost in the Strzelecki Regional Reserve, north-eastern South Australia. These data were used to examine the occurrence and change in frequency of small vertebrates in the region. In January 2003, at the end of a prolonged dry period, reptiles (predominantly geckos) dominated the diet of the barn owl, forming over 74% of Prey Units (PU%). This is the first Australian study to report reptiles as the primary prey of the barn owl. After substantial rain in February 2003, mammalian prey became much more common, and eventually accounted for almost 80 PU%. At least nine species of small mammal, at least four reptiles, nine birds and a frog were identified from the pellets. Mammalian prey included Leggadina forresti, Mus musculus, Notomys fuscus (endangered), Pseudomys desertor (not previously recorded in the reserve), P. hermannsburgensis, Planigale gilesi, Sminthopsis crassicaudata, S. macroura and Tadarida australis. This research showed that barn owls are capable of switching to alternative prey when mammals become rare, but that they return to preferred prey as soon as it becomes available.

Late-Holocene mammal fauna from southern Australia reveals rapid species declines post-European settlement: Implications for conservation biology

The arrival in Australia of Europeans and the species they brought with them initiated a sharp decline in native mammalian biodiversity. Consequently, one-third of the original or pre-European terrestrial mammal fauna is now extinct or threatened with extinction. Although the distributional ranges of many Australian mammals have contracted markedly, modern distributions are frequently used as baselines for conservation management and understanding ecological requirements. However, these often poorly reflect pre-European distributions, particularly in areas where biodiversity declines were rapid and occurred soon after European arrival. Here we analyse two late Holocene mammalian assemblages from Fleurieu Peninsula, South Australia, and reconstruct the pre-European terrestrial non-volant mammal fauna. The region was previously estimated to have lost perhaps 30% of its original terrestrial non-volant mammal fauna, but our results indicate a loss of almost 50%. We provide the first local records of the murids Mastacomys fuscus, Pseudomys australis, P. gouldii, P. novaehollandiae and P. shortridgei, and confirm the past occurrence of the now-extinct Conilurus albipes. Our study contributes new knowledge of species biogeography and ecology and will help refine restoration targets.

Cryptic grey-bellied dunnart (Sminthopsis griseoventer) discovered in South Australia: genetic, morphological and subfossil analyses show the value of collecting voucher material

The assumption that almost all mammal species are known to science has led to a recent trend away from collecting voucher specimens/tissues during field studies. Here we present a case study of a recently discovered cryptic marsupial (Sminthopsis griseoventer) in South Australia (SA) and show how such collections can contribute to rigorous biodiversity and biogeographic assessments. Morphological and genetic (allozyme and mitochondrial control region (CR) sequence data) analyses, including ancient DNA analyses of type material, were applied to 188 voucher specimens and 94 non-vouchered tissues of Sminthopsis held at the SA Museum. These data were used to confirm the presence of S. griseoventer in SA, validate means of identifying it morphologically and describe recent and pre-European distributions. Pelage differences between S. griseoventer and S. dolichura enabled their identification, but external measurements overlapped considerably. Subfossil S. griseoventer were identified from seven deposits and confirmed that in the past the species was more widespread in SA. CR divergences (>1.8%) among Western Australian and SA S. griseoventer suggested its long-term presence in SA. Discrepancies between the mitochondrial and allozyme affinities of S. aitkeni and S. griseoventer, coupled with the lack of obvious morphological differences, indicate that a taxonomic reappraisal of these species is warranted. The study strongly demonstrates an ongoing need for the routine collection of mammal voucher material in biological and environmental impact surveys.

Additional AMS radiocarbon dates for Wet Cave and the timing of megafaunal extinctions in the Naracoorte region of South Australia

Previously published AMS radiocarbon ages for charcoal obtained from a stratigraphic profile at Wet Cave (5U10), Naracoorte World Heritage Area, southeastern South Australia (Pate et al. 2002), suggested that a range of megafauna disappeared from the site by ca. 45,000 years ago. The Wet Cave radiocarbon chronology provided additional data to support claims for a continentwide extinction of megafauna in Australia by about 46,000 years ago (See Miller et al. 1999, 2005; Roberts et al. 2001, Johnson & Prideaux 2004, Johnson 2005). Here we report an additional eight AMS radiocarbon ages for charcoal from the same stratigraphic sequence at Wet Cave in order to provide other researchers with access to the expanded dataset.

Chronology and stratigraphy of the Wet Cave vertebrate fossil deposit, Naracoorte, and relationship to paleoclimatic conditions of the Last Glacial Cycle in south-eastern Australia

The Wet Cave vertebrate fossil deposit of the Naracoorte Caves in south-eastern South Australia contains a rich and diverse assemblage of small mammal fauna known to span the Upper Pleistocene–Holocene. Here, we describe five previously unidentified in situ units (A, B, C, E and F) and one likely reworked unit (D) in the Wet Cave sedimentary profile, which are correlated with paleoclimatic conditions associated with the Last Glacial Cycle. Additional radiocarbon dates presented here provide a finer temporal resolution for the upper sections of the sequence than previously available and reveal rapid deposition of polished quartz sands laminated with brown silts during the last glacial maximum (LGM). Change in sediment type and depositional processes are dated from 16.8 to 16.4 k cal y BP and are associated with the onset of deglaciation. The characteristics of the five in situ depositional units are similar to those identified from the contemporaneous fossil and sedimentary sequence of Blanche Cave 3rd Chamber, located approximately 400 m away, reflecting interactions between paleoclimate, sediment mobility and deposition at this locality. Greater variation is evident between the Wet Cave sedimentary profile and the inner chamber of Robertson Cave, located approximately 6 km away and shows that local processes and cave structure exerted some control on sediment accumulation. Paleoclimatic inferences from the depositional sequence of Wet Cave are broadly consistent with those inferred from regional landforms for south-eastern Australia but provide a local signal more suitable for cross-correlation of the fossil faunas. In particular, the Wet Cave sequence suggests that local conditions were relatively stable in the lead up to the LGM despite fluctuation in both local and regional effective precipitation. Sedimentary units associated with the post-LGM deglaciation are characterised by alternating sand and sandy-silt layers, assumed to reflect the impact of enhanced seasonality and/or climatic fluctuation leading towards the Holocene.

Using the diet of the barn owl (Tyto alba) as an indicator of small vertebrate abundance in the Channel Country, south-western Queensland

The diet of the barn owl (Tyto alba) was determined by analysing pellets and bulk pellet debris found in the ruins of Baryulah Homestead, south-western Queensland. Nine species of mammal, at least eight bird, five reptile and three frog species were identified. The majority of prey consisted of small mammals and was dominated by Mus musculus, which accounted for almost 40 Prey Unit percent (PU%) of all prey. Rattus villosissimus was an important secondary prey species, which, due to its comparatively large mass, contributed 21.79 PU%. Other native mammals were present in low frequency only. Reptiles (primarily geckos) were more abundant than expected, collectively contributing >15 PU%, suggesting that they were an important component of the barn owl’s diet.

Morphological and molecular evidence supports specific recognition of the recently extinct Bettongia anhydra (Marsupialia: Macropodidae)

In 1933, geologist and explorer Michael Terry collected the skull of a small macropodid captured by members of his party near Lake Mackay, western Northern Territory. In 1957, this skull was described as the sole exemplar of a distinct subspecies, Bettongia penicillata anhydra, but was later synonymized with B. lesueur and thereafter all but forgotten. We use a combination of craniodental morphology and ancient mitochondrial DNA to confirm that the Lake Mackay specimen is taxonomically distinct from all other species of Bettongia and recognize an additional specimen from a Western Australian Holocene fossil accumulation. B. anhydra is morphologically and genetically most similar to B. lesueur but differs in premolar shape, rostrum length, dentary proportions, and molar size gradient. In addition, it has a substantial mitochondrial cytochrome b pairwise distance of 9.6–12% relative to all other bettongs. The elevation of this recently extinct bettong to species status indicates that Australias mammal extinction record over the past 2 centuries is even worse than currently accepted. Like other bettongs, B. anhydra probably excavated much of its food and may have performed valuable ecological services that improved soil structure and water infiltration and retention, as well as playing an important role in the dispersal of seeds and mycorrhizal fungal spores. All extant species of Bettongia have experienced extensive range contractions since European colonization and some now persist only on island refugia. The near total loss of these ecosystem engineers from the Australian landscape has far-reaching ecological implications.