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West Perth, Australia

Chambers L.E.,Center for Australian Weather and Climate Research | Devney C.A.,James Cook University | Congdon B.C.,James Cook University | Dunlop N.,Conservation Council WA | And 2 more authors.
Emu | Year: 2011

Although there is growing evidence of climate warming, for many regions the broader effects of climate variation on marine top predators remains unknown owing to the difficulty in obtaining, for synthesis, long-term and short-term datasets on multiple species. In the Australian region, climatic and oceanographic variability and change have been shown to affect marine species, often with profound consequences. Many seabirds are apex predators for which changes in climatic and oceanic dynamics have driven range movements poleward, reduced breeding success and altered breeding timing for some species. Here we review the literature to assess and determine the vulnerability of Australian seabirds to variation and change in climate and identify which species and ecosystems may be more resilient to future climate warming. It is clear from this synthesis that not all Australian seabirds are affected similarly, with responses varying by species and location. In addition, the paucity of information on the distribution and biology of seabird prey, foraging patterns and movements of seabirds, and the ability of seabirds to switch between prey species or adjust timing of life-cycles make generalisations about potential effects of future climate change and adaptive capacity in seabirds difficult. This applies both within Australia and elsewhere, where data are similarly sparse. © 2011 Royal Australasian Ornithologists Union. Source

The activity levels of seven species of insectivorous microbats in five habitats widespread across the Charles Darwin Reserve in the Murchison region of Western Australia were measured using echolocation detectors and compared with results of habitat usage revealed by stable isotope analysis. The activity levels were further compared with projective foliage density as a surrogate of productivity within each habitat. Habitat use, estimated from echolocation activity of the microbat species and from stable isotope analysis of their fur, agree and each provides complementary information on the habitats preferred by species. Both methods show that five of the species, Chalinolobus gouldii, C. morio, Mormopterus species 3, Nyctophilus geoffroyi and Tadarida australis, are active and forage over each of the five habitats. Scotorepens balstoni is shown by both methods to prefer habitats with C3 woodland over C4 shrubs and grasses. Vespadelus baverstocki is shown by both methods to fly and forage over habitats with developed arid-zone shrubland understorey vegetation. The echolocation method shows that bat activity levels align with the foliage mass of the vegetation as measured by the projected foliage density. The species' stable isotope signatures show that the insects captured are feeding primarily on the ground cover of the habitats. The two species that have high C signatures, S. balstoni and V. baverstocki, are shown to be most active in habitats with a C4 ground cover. © Australian Rangeland Society 2012. Source

The microbat assemblage on Charles Darwin Reserve was investigated between 2007 and 2009 to provide a benchmark for monitoring long-term responses to climate change on a major bioregional boundary, the mulgaeucalypt line. Stable isotope analysis of bat fur was used to interpret the current local habitat and trophic relationships between microbat species with different biogeographical affinities. The stable isotope values of the ants inhabiting 10 broad vegetation types were used to provide an isotopic baseline of the Reserve to assist in the interpretation of the C or N signatures observed in the bat assemblage. The C signatures of ants in both a Salmon Gum woodland and an arid shrubland shifted significantly after the breaking of a prolonged drought but there was no change in the bats. The ubiquitous bat species, and those with south-western affinities, probably used most of the available vegetation types on the Reserve and displayed some significant differences in mean trophic level. Scotorepens balstoni, a species of the southern interior of Western Australia, specialised at foraging within patches of eucalypt woodland. Vespadelus baverstocki, a southern arid zone species, was evidently restricted to the proximal arid habitats with distinctively high N signatures. © 2011 Australian Rangeland Society. Source

This paper uses stable isotope analysis to examine the foraging ecology of the tropical dark terns breeding in the subtropics off southwestern Australia and wintering at lower geographic latitudes. The δ 13C and δ 15N values of feathers and eggshell membranes indicated that Brown Noddies Anous stolidus breeding in this region were foraging in waters characterised by higher inorganic nitrogen availability and productivity than those occupied by Bridled Terns Onychoprion anaethetus. However, Bridled Terns probably foraged at a higher trophic level than Brown Noddies, and this was probably related to their habit of foraging on a range of marine organisms associated with floating rafts of macro-algae and other flotsam. The δ 13C and δ 15N values of adult primary feathers indicated that Sooty Terns Onychoprion fuscata and Bridled Terns foraged in wintering areas close to the equator, but Sooty Terns again utilised more productive water masses. The Brown Noddies breeding off southwestern Australia appear to winter closer to the subtropics than Bridled and Sooty Terns. Source

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