Body Temperature In Captive Long-Beaked Echidnas (Zaglossus Bartoni)

The routine occurrence of both short-term (daily) and long-term torpor (hibernation) in short-beaked echidnas, but not platypus, raises questions about the third monotreme genus, New Guinea's Zaglossus. We measured body temperatures (Tb) with implanted data loggers over three and a half years in two captive Zaglossus bartoni at Taronga Zoo, Sydney. The modal Tb of both long-beaks was 31 degrees C, similar to non-hibernating short-beaked echidnas, Tachyglossus aculeatus, in the wild (30-32 degrees C) and to platypus (32 degrees C), suggesting that this is characteristic of normothermic monotremes. Tb cycled daily, usually over 2-4 degrees C. There were some departures from this pattern to suggest periods of inactivity but nothing to indicate the occurrence of long-term torpor. In contrast, two short-beaked echidnas monitored concurrently in the same pen showed extended periods of low Tb in the cooler months (hibernation) and short periods of torpor at any time of the year, as they do in the wild. Whether torpor or hibernation occurs in Zaglossus in the wild or in juveniles remains unknown. However, given that the environment in this study was conducive to hibernation in short-beaks, which do not easily enter torpor in captivity, and their large size, we think that torpor in wild adult Zaglossus is unlikely

Application of an Ultralight Aircraft to Aerial Surveys of Kangaroos on Grazing Properties

A Drifter ultralight aircraft was used as a platform for line-transect aerial surveys of three species of kangaroo in the sheep rangelands south-east of Blackall and north of Longreach in central-western Queensland in winter 1993 and 1994. Favourable comparisons between the results of ultralight surveys and those made from a helicopter flying the same transects and foot surveys along another set of transects, all within a few days of the ultralight survey, confirmed the expectation we had that an ultralight would be a satisfactory and much cheaper vehicle for conducting aerial surveys of kangaroos. The comparisons are even more favourable when data for the three species surveyed are combined, pointing to a problem in species identification and underlining the importance of using only experienced observers for aerial survey of kangaroos, whatever the platform. The use of an ultralight aircraft could have particular value where a comparatively small area, such as an individual sheep or cattle property, is under consideration. In this paper, we present the numerical comparisons, along with an evaluation of the practicability of using this type of aircraft. We also describe a possible future scenario in which an accreditation process could see approved kangaroo surveyors undertaking property assessments by ultralight, under contract to graziers or other interested parties

Shelter selection and home range of echidnas, tachyglossus aculeatus, in the highlands of South-East Queensland

We recorded physical attributes of sites used for daily shelter or as hibernacula by nine echidnas, Tachyglossus aculeatus, living on a sheep grazing property in southeastern Queensland. Home ranges were also determined. For daily shelter sites, echidnas most often used hollow logs and depressions under the roots of fallen trees. Daily shelters were found more often on north-facing slopes and usually provided >90% cover. Hibernation sites always provided 100% cover but, in contrast to daily sites, were distributed randomly in relation to the slope of the terrain. Rabbit burrows, which offer much better thermal buffering than hollow logs, were used most commonly as hibernacula. There were differences between individuals in the type of shelter they used and, moreover, echidnas did not use shelter sites in proportion to what was available, indicating that choice was being exercised. Re-use of sites occurred non-randomly, implying that echidnas can recognise previously used shelters and probably have a learned familiarity with their living area. Home ranges varied between 20.6 ha and 93.3 ha (mean = 49.8, s.d. = 25.4), overlapped with those of other echidnas and correlated positively with body weight

Spatial and seasonal relationships between Pacific harbor seals (Phoca vitulina richardii) and their prey, at multiple scales

Knowing where pinnipeds forage is vital to managing and protecting their populations, and for assessing potential interactions with fisheries. We assessed the spatial relationship between the seasonal distribution of Pacific harbor seals (Phoca vitulina richardii) outfitted with satellite transmitters and the seasonal distributions of potential harbor seal prey species in San Francisco Bay, California. Pearson’s correlation coefficients were calculated between the number of harbor seal locations in an area of the San Francisco Bay and the abundance of specific prey species in the same area. The influence of scale on the analyses was assessed by varying the scale of analysis from 1 to 10 km. There was consistency in the prey species targeted by harbor seals year-round, although there were seasonal differences between the most important prey species. The highest correlations between harbor seals and their prey were found for seasonally abundant benthic species, located within about 10 km of the primary haul-out site. Probable foraging habitat for harbor seals was identified, based on areas with high abundances of prey species that were strongly correlated with harbor seal distribution. With comparable local data inputs, this approach has potential application to pinniped management in other areas, and to decisions about the location of marine reserves designed to protect these species

Crocodiles as dinosaurs: Behavioural thermoregulation in very large ectotherms leads to high and stable body temperatures

Empirical field data describing daily and seasonal cycles in body temperature (Tb) of free-ranging Crocodylus porosus (32-1010 kg) can be predicted by a mathematical analysis. The analysis provides a mechanistic explanation for the decreased amplitude of daily cycles in Tb and the increase in 'average' Tb with increasing mass. Assessments of 'average' daily Tb were made by dividing the integral of the difference between measured values of Tb and minimum operative temperature by the period of integration, to yield a thermal index expressing relative 'warmth' of crocodiles. The average daily Tb of a 1010 kg crocodile was 3.7 degrees C warmer than that of a 42 kg individual in summer and 1.9 degreesC warmer than that of a 32 kg individual in winter. The success of this mathematical approach confirms that crocodiles are simple ectotherms and that there is unlikely to be a significant contribution to their thermal biology from physiological mechanisms. Behaviour, however, is very important even in large individuals. Crocodiles in the field typically move daily between land and water in cycles that vary seasonally. We predicted Tb for the reverse of these behavioural cycles, which more than doubled seasonal fluctuations in Tb compared with the observed fluctuations. We were also able to predict the Tb of very large, dinosaur-sized crocodiles in a similar climate to that at our study site. A 10 000 kg 'crocodile', for example, would be expected to have a Tb of 31 degreesC in winter, varying by less than 0.1 degrees C during a day when operative temperatures varied by nearly 20 degrees C, from 20 to 38 degrees C. The study confirms that, in low latitudes at least, large dinosaurs must have had an essentially high and stable value of Tb, without any need for endothermy. Also, access to shade or water must have been crucial for the survival of large dinosaurs at low latitudes. Furthermore, the finding of increasing 'average' Tb as ectotherms grow larger may have implications for the metabolic rates of very large reptiles, because the Q10 effect could counteract the downscaling of metabolic rate with mass, an effect that seems not to have been recognised previously

The Evolution of Endothermy and Its Diversity in Mammals and Birds

Many elements of mammalian and avian thermoregulatory mechanisms are present in reptiles and the changes involved in the transition to endothermy are more quantitative than qualitative. Drawing on our experience with reptiles and echidnas, we comment on that transition and on current theories about how it occurred. The theories divide into two categories, depending upon whether selection pressures operated directly or indirectly on mechanisms producing heat. Both categories of theories focus on explaining the evolution of homeothermic endothermy but ignore heterothermy. However, noting that hibernation and torpor are almost certainly plesiomorphic (= ancestral, primitive), and that heterothermy is very common among endotherms, we propose that homeothermic endothermy evolved via heterothermy, with the earliest protoendotherms being facultatively endothermic and retaining their ectothermic capacity for "constitutional eurythermy". Thus, unlike current models for the evolution of endothermy which assume that hibernation and torpor are specialisations arising from homeothermic ancestry, and therefore irrelevant, we consider that they are central. We note the sophistication of thermoregulatory behavior and control in reptiles, including precise control over conductance, and argue that brooding endothermy seen in some otherwise ectothermic Boidae suggests an incipient capacity for facultative endothermy in reptiles. We suggest that the earliest insulation in protoendotherms may have been internal, arising from of re-distribution of the fat bodies which are typical of reptiles. We note that short-beaked echidnas provide a useful living model of what an (advanced) protoendotherm may have been like. Echdinas have the advantages of endothermy, including the capacity for homeothermic endothermy during incubation, but are very relaxed in their thermoregulatory precision and minimise energetic costs by using ectothermy facultatively when entering short or long term torpor. They also have a substantial layer of internal dorsal insulation. We favor theories about the evolution of endothermy which invoke direct selection for the benefits conferred by warmth, such as expanding daily activity into the night, higher capacities for sustained activity, higher digestion rates, climatic range expansion and, not unrelated, control over incubation temperature and the benefits for parental care. We present an indicative, stepwise schema in which observed patterns of body temperature are a consequence of selection pressures, the underlying mechanisms and energy optimization, and in which homeothermy results when it is energetically desirable, rather than as the logical endpoint

Body Temperatures and Activity Patterns of Tasmanian Devils (Sarcophilus harrisii) and Eastern Quolls (Dasyurus viverrinus) through a Subalpine Winter

During a field study of carnivorous dasyurid marsupials in subalpine Tasmania, the trapping success for Tasmanian devils (Sarcophilus harrisii), but not for spotted-tailed quolls (Dasyurus maculatus) or eastern quolls (Dasyurus viverrinus), was significantly lower when winter weather conditions turned to sleet or snow or when deep snow lay on the ground. This field study was instigated to determine if devils and eastern quolls spend more time in burrows in severe weather conditions and if they enter torpor. Torpor is known to occur in eutherian mammals as large as devils and in a similar-sized congeneric marsupial, the western quoll (Dasyurus geoffroyi). Using radiotelemetry, body temperatures of Tasmanian devils and eastern quolls ranging freely in their natural habitat were monitored throughout winter. Neither species was observed in torpor, even under prolonged severe weather conditions, and the number of hours spent active did not differ between summer and winter or between moderate and severe winter weather conditions. Body temperatures averaged 36.5 degrees C (SD = 0.079, range of 33.5 degrees -38.6 degrees C) for the three male eastern quolls and 35.7 degrees C (SD = 0.575, range of 31.3 degrees - 37.5 degrees C) for the four (male and female) devils. A diel cycle in body temperature occurred in both species; temperatures rose each evening when animals became active, remained high throughout the night despite ambient temperatures falling to the diel minima, and were lower during the day when the individuals were inactive in dens. The amplitude of this cycle was greater in eastern quolls (1.1 degrees C, SD = 0.142) than in devils (0.6 degrees C, SD = 0.252)