It is unclear whether torpor really is uncommon amongst passerine birds. We therefore examined body temperature and thermoregulatory strategies of an Austral passerine, the white-browed babbler (Pomatostomus superciliosus), which has characteristics related to a high probability of torpor use; it is a sedentary, insectivorous, cooperative breeding species, which we studied during winter in a temperate habitat. Wild, free-living babblers maintained normothermy overnight, even at sub-zero ambient temperatures, with a mean minimum body temperature of 38.5±0.04°C that was independent of minimum black bulb temperature. Physiological variables measured in the laboratory revealed that babblers had a low basal metabolic rate and evaporative water loss, but their body temperature and thermal conductance were typical of those of other birds and they had a typical endothermic response to low ambient temperature. Huddling yielded significant energy savings at low temperatures and a roost nest created a microclimate that buffered against low temperatures. Low basal energy requirements, communal roosting and the insulation of a roost nest confer sufficient energetic benefits, allowing babblers to meet energy requirements without resorting to heterothermia, even in their depauperate, low-productivity landscape, suggesting that passerine birds use alternatives to torpor to balance their energy budgets when possible.
In an era characterized by recurrent large wildfires in many parts of the globe, there is a critical need to understand how animal species respond to fires, the rates at which populations can recover, and the functional changes fires may cause. Using quantified changes in habitat parameters over a~400-yr post-fire chronosequence in an obligate-seeding Australian eucalypt woodland, we build and test predictions of how birds, as individual species and aggregated into functional groups according to their use of specific habitat resources, respond to time since fire. Individual bird species exhibited four generalized response types to time since fire: incline, decline, delayed, and bell. All significant relationships between bird functional group richness or abundance and time since fire were consistent with predictions based on known time-since-fire-associated changes in habitat features putatively important for these bird groups. Consequently, we argue that the bird community is responding to post-fire successional changes in habitat as per the habitat accommodation model, rather than to time since fire per se, and that our functional framework will be of value in predicting bird responses to future disturbances in this and other obligate-seeder forest and woodland ecosystems. Most bird species and functional groups that were affected by time since fire were associated with long-unburned woodlands. In the context of recent large, stand-replacement wildfires that have affected a substantial proportion of obligate-seeder eucalypt woodlands, and the multi-century timescales over which post-fire succession occurs, it would appear preferable from a bird conservation perspective if fires initiating loss of currently long-unburned woodlands were minimized. Once long-unburned woodlands are transformed by fire into recently burned woodlands, there is limited scope for alternative management interventions to accelerate the rate of habitat development after fire, or supplement the resources formerly provided to birds by long-unburned woodlands, with the limited exception of augmenting hollow availability for key hollow-nesting species.
The Australian Fairy Tern Sternula nereis nereis is a seabird that breeds along the coast and whose small populations are dispersed over vast stretches of the Australian seaboard and nearshore islands. In recent years, citizen science programs have been developed to bolster monitoring efforts to better understand breeding success and identify site threat profiles. The development of protocols that facilitate the collection of consistent measurements is important for long-term monitoring of this threatened (Vulnerable) species. This study describes plumage development and age-related behaviour in juvenile Australian Fairy Terns using direct observations and photographic recapture of individually marked birds. This information may be used as the basis for the development of a field ageing guide, enabling the collection of standardised information on colony demographics and juvenile development. A temporary colour-banding study was trialled by painting nail varnish onto 15 Australian Bird and Bat Banding Scheme (ABBBS) incoloy bands, avoiding the need to band nestlings with additional readable or PVC colour-bands. The varnish remained intact, albeit chipped, on four surviving birds that were resighted ≤80 days after banding, enabling the identification of individuals away from the colony site, without the need for recapture. The temporary marking of ABBBS bands using nail varnish offered an effective short-term solution for identifying individual juvenile Fairy Terns in the field and for describing plumage changes over a period of c. 3 months.
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