Metabolic physiology of euthermic and torpid honey possums, Tarsipes rostratus

Euthermic honey possums have a higher body temperature (Tb), basal metabolic rate and wet thermal conductance than other marsupials of similar mass. Honey possums enter torpor when cold-stressed and deprived of food. The pattern of decline in body temperature and oxygen consumption during torpor generally resembles that of other heterothermic endotherms. The duration of torpor bouts in honey possums was about 10 h; torpor bouts longer than one day were not observed. The Tb, declined during torpor to within 1-2°C of ambient temperature (Ta>5°C) and oxygen consumption rate declined dramatically. The minimal body temperature (Tb min) measured for torpid honey possums was about 5°C, because Tb was regulated at about 5°C by honey possums torpid at Ta 10-15°C) and short-term torpor cycles (e.g. in dasyurids); (2) deep (Tb, min< 10°C) and multi-day torpor cycles (e.g. in burramyids). Honey possums appear to have a third pattern of deep (Tb, min= 5°C) but short-term torpor. The ecological reasons for this pattern of deep torpor and the apparent absence of multi-day torpor in honey possums may be related to their nectarivorous diet and lack of extensive fat stores

Diet of Ctenotus xenopleura (Reptilia: Scincidae) in the southern Goldfields of Western Australia

The diet of Ctenotus xenopleura, a species found in spinifex grasslands in the southern Goldfields of Western Australia, consisted primarily of termites. The high proportion of termites was consistent over different sampling periods, and was higher than observed for most other Ctenotus species. It is not clear whether this high proportion of termites is the result of specialised foraging for termites by C. xenopleura

Standard metabolic rates of three nectarivorous meliphagid passerine birds

Standard metabolic rate (VO2 STD) was determined for three species of passerine bird from the family Meliphagidae to investigate the possible effect of nectarivory on standard metabolic rate in this family. The three species that we investigated did not show a significant departure from allometric predictions of standard metabolic rate for passerine species. Disparities between standard metabolic rate for meliphagids in the present study and previous data appear to reflect methodological differences, and no general allometric relationship is apparent for meliphagids at present. In meliphagids, nectarivory per se is not an important correlate with standard metabolic rate. Data from additional meliphagid species, collected under standardised conditions, are required to confirm the generality of the findings of the present study, that nectarivorous meliphagids have a standard metabolic rate typical of passerine birds

Patterns of diet and microhabitat use by four species of sympatric Ctenotus lizards: Do they reveal foraging specialisation?

The foraging ecology of many Ctenotus species is considered to be generalised and opportunistic. If their foraging ecology is generalised, we would predict that Ctenotus species in spinifex grasslands of and Australia will (1) feed largely on the most abundant food source, termites and (2) that any differences in diet will largely reflect differences in microhabitat use. To test these predictions, we examined diets and patterns of microhabitat use by four sympatric Ctenotus species in the southern Goldfields of Western Australia. Neither prediction was supported by our results. One species, C. brooksi, did not feed on termites and similarity in microhabitat use between species was not related to dietary similarity. Our data suggest that these Ctenotus species may have more specialised foraging ecologies than has been previously appreciated. Future research involving detailed observations of Ctenotus species foraging in the field is required to determine which species have specialised foraging ecologies and to what extent they are specialised

Energetics and water relations of Namib desert rodents

No Abstract

Are day-active small mammals rare and small birds abundant in Australian desert environments because small mammals are inferior thermoregulators?

Small desert birds are typically diurnal and highly mobile (hence conspicuous) whereas small non-volant mammals are generally nocturnal and less mobile (hence inconspicuous). Birds are more mobile than terrestrial mammals on a local and geographic scale, and most desert birds are not endemic but simply move to avoid the extremes of desert conditions. Many small desert mammals are relatively sedentary and regularly use physiological adjustments to cope with their desert environment (e.g., aestivation or hibernation). It seems likely that prey activity patterns and reduced conspicuousness to predators have reinforced nocturnality in small desert mammals. Differences such as nocturnality and mobility simply reflect differing life-history traits of birds and mammals rather than being a direct result of their differences in physiological capacity for tolerating daytime desert conditions.<br /