A heterothermic spectrum in hummingbirds

Many endotherms use torpor, saving energy by a controlled reduction of their body temperature and metabolic rate. Some species (e.g., arctic ground squirrels, hummingbirds) enter deep torpor, dropping their body temperatures by 23-37°C, while others can only enter shallow torpor (e.g., pigeons, 3-10°C reductions). However, deep torpor in mammals can increase predation risk (unless animals are in burrows or caves), inhibit immune function, and result in sleep deprivation, so even for species that can enter deep torpor, facultative shallow torpor might help balance energy savings with these potential costs. Deep torpor occurs in three avian orders, but the trade-offs of deep torpor in birds are unknown. Although the literature hints that some bird species (mousebirds and perhaps hummingbirds) can use both shallow and deep torpor, little empirical evidence of such an avian heterothermy spectrum within species exists. We infrared imaged three hummingbird species that are known to use deep torpor, under natural temperature and light cycles, to test if they were also capable of shallow torpor. All three species used both deep and shallow torpor, often on the same night. Depending on the species, they used shallow torpor for 5-35% of the night. The presence of a heterothermic spectrum in these bird species indicates a capacity for fine-scale physiological and genetic regulation of avian torpid metabolism.

Case Report: Anorexia as a new type of adverse reaction caused by the COVID-19 vaccination: a case report applying detailed personal care records

Background: In Japan, more than 1,000 participants died shortly after receiving the coronavirus disease 2019 (COVID-19) vaccine, but the causal relation between the injection and death remains uncertain. Methods: Applying long-term personal vital care data for 28 months for an elderly patient, I investigated and evidenced adverse reactions after the first dose of the COVID-19 Pfizer vaccination. Results: The precise, detailed, and continuous data statistically clarified the long-term fevers associated with no meals or drinks. Interrupted time series analysis showed significant and fluctuating increases of body temperatures, pressures, and pulses, although solely long-term plots showed an abrupt and timely increase in these vital data after the vaccine. Conclusions: Anorexia was fatal, and newly reported in the present care records since the patient received the first dose of the COVID-19 vaccine.

Do Incubation Temperatures Affect the Preferred Body Temperatures of Hatchling Velvet Geckos?

In many lizards, a mother’s choice of nest site can influence the thermal and hydric regimes experienced by developing embryos, which in turn can influence key traits putatively linked to fitness, such as body size, learning ability, and locomotor performance. Future increases in nest temperatures predicted under climate warming could potentially influence hatchling traits in many reptiles. In this study, we investigated whether future nest temperatures affected the thermal preferences of hatchling velvet geckos, Amalosia lesueurii. We incubated eggs under two fluctuating temperature treatments; the warm treatment mimicked temperatures of currently used communal nests (mean = 24.3°C, range 18.4–31.1°C), while the hot treatment (mean = 28.9°C, range 20.7–38.1°C) mimicked potential temperatures likely to occur during hot summers. We placed hatchlings inside a thermal gradient and measured their preferred body temperatures (Tbs) after they had access to food, and after they had fasted for 5 days. We found that hatchling feeding status significantly affected their preferred Tbs. Hatchlings maintained higher Tbs after feeding (mean = 30.6°C, interquartile range = 29.6–32.0°C) than when they had fasted for 5 d (mean = 25.8°C, interquartile range = 24.7–26.9°C). Surprisingly, we found that incubation temperatures did not influence the thermal preferences of hatchling velvet geckos. Hence, predicting how future changes in nest temperatures will affect reptiles will require a better understanding of how incubation and post-hatchling environments shape hatchling phenotypes.

Interspecific Interactions: A Case Study using the Tuatara-Fairy Prion Association

<p>Some of the key relationships in the life of an organism are interactions with individuals of other species within the community, for example, negative interactions such as predation and competition are well known to shape natural communities. Positive interactions also have well documented influences, such as intertidal seaweed canopies extending the distribution of many organisms to higher tidal heights, by reducing thermal and desiccation stresses. However, investigating interactions and measuring their significance for fitness is notoriously difficult. For example, several groups of fish are known to ‘clean’ other fish species by feeding on their ectoparasites, a mutually beneficial arrangement. However, foraging by cleaners can damage scales of their hosts and this interaction can become parasitic in times of low ectoparasite abundance. Using both field and laboratory data, I investigated factors that influenced the dynamics of an unusual vertebrate association, the cohabitation of tuatara and fairy prions in a burrow. The end goal was to contribute to the understanding of the classification of this association. The fairy prion is a seabird that comes to land only for the breeding season and the tuatara is a burrowing reptile, active primarily at night in a temperate climate. Specifically, I measured the effects that this association had on tuatara thermoregulation, and demonstrated the difficulty in applying that information to categorize a complex interaction. Investigations into the temporal and spatial habitat of the tuatara, and the degree to which this influenced thermal opportunities, revealed that mean tuatara body temperatures were always within mean environmental temperatures. Males and females did not differ in mean body temperature or effectiveness of thermoregulation. Body size did not predict body temperature or cooling rates, but heating rates were influenced, with larger animals heating faster than smaller individuals. The presence of a fairy prion in a burrow increased humidity within the burrow, and tuatara that occupied burrows containing a fairy prion were able to maintain up to 1.8°C higher body temperatures through the night during the austral summer months. Thus, burrow use behaviour and burrow selection had greater influences on tuatara body temperature than an individual’s sex or size. Experimental evidence revealed that tuatara are capable of adjusting their habitat selection behaviour in response to different humidity constraints. More time was spent outside the burrows and tuatara were more active under humid laboratory conditions. Use of the burrow by tuatara almost halved the time that fairy prions spent at the burrow with their chick, indicating that tuatara were having a negative effect on fairy prions’ use of their burrow. There was no evidence to support the fact that fairy prions were gaining any fitness benefits from their association with tuatara. Thus, we cannot call this interaction a commensalism or a mutualism. In certain instances, it may be that this interaction is best classed as a parasitism with the tuatara benefitting from burrow use and easy predation opportunities, to the detriment of the lifetime reproductive success of the fairy prion. In other instances it may simply be a case of competition for a limited resource (a burrow) with the outcome varying depending on the individuals and the circumstances involved. Being able to categorize interactions between species of high conservation value or at least to have an understanding of the costs and benefits associated with the interaction is desirable for conservation purposes, as failure to consider the ecological network within which a threatened species is embedded, may lead to counterproductive management measures. Further, these results can be used to develop future research into how climatic changes in temperature and rainfall may interact with habitat availability to influence the full range of natural outcomes of the tuatara-fairy prion association.</p>

Interspecific Interactions: A Case Study using the Tuatara-Fairy Prion Association

<p>Some of the key relationships in the life of an organism are interactions with individuals of other species within the community, for example, negative interactions such as predation and competition are well known to shape natural communities. Positive interactions also have well documented influences, such as intertidal seaweed canopies extending the distribution of many organisms to higher tidal heights, by reducing thermal and desiccation stresses. However, investigating interactions and measuring their significance for fitness is notoriously difficult. For example, several groups of fish are known to ‘clean’ other fish species by feeding on their ectoparasites, a mutually beneficial arrangement. However, foraging by cleaners can damage scales of their hosts and this interaction can become parasitic in times of low ectoparasite abundance. Using both field and laboratory data, I investigated factors that influenced the dynamics of an unusual vertebrate association, the cohabitation of tuatara and fairy prions in a burrow. The end goal was to contribute to the understanding of the classification of this association. The fairy prion is a seabird that comes to land only for the breeding season and the tuatara is a burrowing reptile, active primarily at night in a temperate climate. Specifically, I measured the effects that this association had on tuatara thermoregulation, and demonstrated the difficulty in applying that information to categorize a complex interaction. Investigations into the temporal and spatial habitat of the tuatara, and the degree to which this influenced thermal opportunities, revealed that mean tuatara body temperatures were always within mean environmental temperatures. Males and females did not differ in mean body temperature or effectiveness of thermoregulation. Body size did not predict body temperature or cooling rates, but heating rates were influenced, with larger animals heating faster than smaller individuals. The presence of a fairy prion in a burrow increased humidity within the burrow, and tuatara that occupied burrows containing a fairy prion were able to maintain up to 1.8°C higher body temperatures through the night during the austral summer months. Thus, burrow use behaviour and burrow selection had greater influences on tuatara body temperature than an individual’s sex or size. Experimental evidence revealed that tuatara are capable of adjusting their habitat selection behaviour in response to different humidity constraints. More time was spent outside the burrows and tuatara were more active under humid laboratory conditions. Use of the burrow by tuatara almost halved the time that fairy prions spent at the burrow with their chick, indicating that tuatara were having a negative effect on fairy prions’ use of their burrow. There was no evidence to support the fact that fairy prions were gaining any fitness benefits from their association with tuatara. Thus, we cannot call this interaction a commensalism or a mutualism. In certain instances, it may be that this interaction is best classed as a parasitism with the tuatara benefitting from burrow use and easy predation opportunities, to the detriment of the lifetime reproductive success of the fairy prion. In other instances it may simply be a case of competition for a limited resource (a burrow) with the outcome varying depending on the individuals and the circumstances involved. Being able to categorize interactions between species of high conservation value or at least to have an understanding of the costs and benefits associated with the interaction is desirable for conservation purposes, as failure to consider the ecological network within which a threatened species is embedded, may lead to counterproductive management measures. Further, these results can be used to develop future research into how climatic changes in temperature and rainfall may interact with habitat availability to influence the full range of natural outcomes of the tuatara-fairy prion association.</p>

Body Temperature Frequency Distributions: A Tool for Assessing Thermal Performance in Endotherms?

There is increasing recognition that rather than being fully homeothermic, most endotherms display some degree of flexibility in body temperature. However, the degree to which this occurs varies widely from the relatively strict homeothermy in species, such as humans to the dramatic seasonal hibernation seen in Holarctic ground squirrels, to many points in between. To date, attempts to analyse this variability within the framework generated by the study of thermal performance curves have been lacking. We tested if frequency distribution histograms of continuous body temperature measurements could provide a useful analogue to a thermal performance curve in endotherms. We provide examples from mammals displaying a range of thermoregulatory phenotypes, break down continuous core body temperature traces into various components (active and rest phase modes, spreads and skew) and compare these components to hypothetical performance curves. We did not find analogous patterns to ectotherm thermal performance curves, in either full datasets or by breaking body temperature values into more biologically relevant components. Most species had either bimodal or right-skewed (or both) distributions for both active and rest phase body temperatures, indicating a greater capacity for mammals to tolerate body temperatures elevated above the optimal temperatures than commonly assumed. We suggest that while core body temperature distributions may prove useful in generating optimal body temperatures for thermal performance studies and in various ecological applications, they may not be a good means of assessing the shape and breath of thermal performance in endotherms. We also urge researchers to move beyond only using mean body temperatures and to embrace the full variability in both active and resting temperatures in endotherms.

PSIII-2 Infrared technology: A potential tool for improved pork production

This study investigated infrared technology (IRT) as a non-invasive tool for identifying febrile or stressed pigs before slaughter. A total of 120 market pigs (BW= 105.1 ± 4.9 kg) were transported in five replicate trips (20–25 pigs/replicate) for ~2 hr to an abattoir during summer 2020. Ocular and body temperatures of the pigs were recorded using a consumer grade digital infrared camera (FLIR C3, FLIR Systems) in lairage immediately after transport. Thermographic images were taken from 0.25m and 2m from pigs’ eyes and body (back/flank), respectively. At slaughter, blood samples were collected from each animal for cortisol, glucose and lactate analyses. Carcass pH measures were taken at 1 and 3 h post-mortem and loin samples were collected for meat quality assessment. Linear regression models (SAS 9.4) were used to evaluate whether post-transport temperature was predictive of blood and meat quality responses using ambient temperature and relative humidity as covariates. There were significant relationships between pigs’ ocular and body temperatures and blood measures. The regression coefficient (r2) of ocular temperatures for blood cortisol, glucose and lactate were 0.15, 0.15 and 0.04, respectively (P ≤0.03). There were significant relationships between pig ocular temperatures and pH taken at 1, 3 and 24 h post-mortem (r2=0.32, 0.18 and 0.51 respectively, P &lt; 0.001). Meat yellowness (b*) and drip loss increased with body temperatures [r2=0.12 (P =0.0002) and 0.05 (P = 0.024), respectively]. Results for Warner-Bratzler shear force showed that higher temperatures were associated with tougher meat (ocular temperature: r2=0.51, P &lt; 0.0001). In conclusion, as pig temperature increased, blood stress markers and drip loss increased and pH at 1 and 3 h post-mortem decreased, indicative of pale, soft and exudative (PSE) meat traits. IRT shows potential for identifying diseased/stressed pigs prior to slaughter and could be a valuable tool for improved food safety and meat quality.

The effect of analytical temperature on thromboelastography tracings in dogs

Viscoelastic testing methods such as thromboelastography (TEG) are becoming increasingly available to veterinarians in a clinical setting. TEG is useful in determining therapeutic transfusion needs and assessing global abnormalities of hemostasis of patients, given that it provides a more comprehensive assessment of coagulation than traditional tests. TEG is standardly performed at 37°C, which is considered a normal body temperature for human patients; however, 37°C is lower than normal body temperature for most canine patients. In an in vitro study, we investigated the potential effect that this difference in body temperature and test temperature might have on TEG results. Citrated blood samples were collected from clinically normal, as well as sick, dogs with various body temperatures. Samples were analyzed concurrently at the patient’s body temperature and at 37°C. There was very high correlation between TEG performed at body temperature and at 37°C for R (min) and MA (mm), high correlation for K (min) and alpha angle (deg), and moderate correlation for LY30 (%) and LY60 (%). For canine patients with normal to mildly abnormal body temperatures, performance of TEG at the standard 37°C is acceptable.