Body surface temperature responses to food restriction in wild and captive great tits.

The winter roosting and awakening behaviour of captive great tits

This study is an experimental demonstration of lethal mobilization of DDT by brown-headed cowbirds (Molothrus ater) and the effects of food deprivation on the distribution and loss of DDT, DDD, and DDE. The principal experimental group consisted of 20 birds fed a dietary dosage of 100 ppm of DDT for 13 days. After 2 days of full rations of untreated food, they were subjected to food restriction. Food was reduced to 43 percent of normal. Seven of the 20 birds died within 4 days. No birds died in the three control groups, treated as follows: ( 1 ) 20 birds fed 100 ppm DDT for 13 days and full rations of untreated food thereafter, (2) 20 birds fed only untreated food but subjected to food restriction, and (3) 20 birds fed full rations of untreated food throughout. In a pilot study, birds were fed 100, 200, or 300 ppm of DDT and subjected to two periods of food restriction, the first of these immediately after dosage ceased and the second 4 months later. DDT-dosed birds from all dosage levels died in each period of food restriction. Before the weight loss that accompanied food restriction, the brains of DDT-dosed birds had concentrations of DDT and DDD that were far below the lethal range. Concentrations increased rapidly to lethal levels. In these birds, DDT in carcasses decreased while DDD increased. DDTdosed birds that died during food restriction lost 16 percent of their total body burden of DDT + DDD + DDE, 21 percent of their weight, and 81 percent of their fat. The DDT-dosed birds that were subjected to food restriction but survived lost a significantly greater proportion of their body burden of residues than similarly dosed birds not subjected to weight loss. Brain levels of DDT and DDD in birds that died during food restriction soon after dosage did not differ significantly from brain levels of birds that died in a period of food restriction 4 months after dosage. Concentrations of DDE were significantly higher in the latter group, although they were lower than concentrations considered to be lethal. In contrast, carcass levels of DDT and DDD were significantly lower, and DDE was only slightly higher, in the birds that died in the second period of food restriction. It is concluded that stored DDT residues present a hazard to birds, which utilize stored fat during periods of stress due to reproduction, cold weather, disease, injury, limited food supply, or migration. DDT [l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane] has been used extensively for insect control in the United States for many years. Direct mortality of birds has followed recommended treatments in many areas (Dustman and Stickel 1966). Birds that survive treatments that kill a portion of the population will themselves carry high residues of DDT in their bodies (Stickel and Stickel 1969). DDT has become sufficiently widespread in the environment so that residues are present in essentially all wild birds and often cannot be traced to specific treatment programs. Mortality of birds due to mobilization of stored DDT during food restriction was suggested by Bernard (1963:178). Additional evidence of the hazard of stored DDT to birds under starvation or other stress was recorded by Stickel ( 1965 ), Ecobichon and Saschenbrecker ( 1969 ), and Stickel and Rhodes (19709. The present study is an experimental demonstration of lethal mobilization of DDT by cowbirds and the effects of food deprivation on the distribution and loss of DDT, DDD, and DDE. We thank W. H. Stickel for assistance in the experiment and D. Hughes for his carefully conducted chemical analyses and his advice on chemical matters.

2020 turned out to be an eventful year – and not just because of the huge impact of COVID-19. From a journal perspective, JEB has seen lots of changes too, particularly within the team of editors. We said a sad farewell to both Michael Dickinson and Editor-in-Chief (EiC) Hans Hoppeler – both of

Photoperiodic control of reproduction in birds is based on two processes, a positive effect leading to gonadal maturation and an inhibitory effect subsequently inducing regression. Nonphotoperiodic cues can modulate photoperiodic control, particularly the inhibitory process. In previous studies of common starlings (Sturnus vulgaris), (1) restriction of food availability to 8 h after dawn had little effect on testicular maturation but dramatically delayed subsequent regression and (2) lower ambient temperature also had little effect during maturation but delayed regression. Could the effects of food restriction and temperature share a common underlying mechanism? Four groups of starlings were kept on a simulated natural cycle in photoperiod in a 2 × 2 factorial experimental design. Two groups were held under an ambient temperature of 16°C, and the other two were held under 6°C. One of each of these groups had food provided ad lib., and in the other two groups access to food was denied 7 h after dawn. In both the ad lib. food groups and the food-restricted groups, lower temperature had little effect on testicular maturation but delayed subsequent regression and molt. In both the 16°C groups and the 6°C groups, food restriction had no effect on testicular maturation but delayed regression and molt. The daily cycle in body temperature was recorded in all groups when the photoperiod had reached 12L∶12D, the photoperiod at which regression is initiated. In both 6°C groups, nighttime body temperature was lower than in the 16°C groups, a characteristic of shorter photoperiods. In the two ad lib. food groups high daytime temperature was maintained until dusk, whereas in the two food-restricted groups body temperature began to decrease after food withdrawal. Thus, both lower temperature and food restriction delayed regression, as if the photoperiod was shorter than it actually was, and both resulted in daily cycles in body temperature that reflected cycles under shorter photoperiods. This implies that the daily cycle in body temperature is possibly a common pathway through which nonphotoperiodic cues may operate.

Background Many behavioural, pharmacological, and metabolic studies in mice require fasting, yet the possibility of fasting-induced torpor affecting data is rarely considered. Torpor is a state characterised by depressed metabolism and profound alterations in physiology and behaviour. In this study, we aimed to determine whether a chronic food restriction paradigm, common in behavioural studies, was sufficient to induce torpor in mice. Methods Mice were food restricted to ~85-90% of their bodyweight, as is typically done, and monitored using continuous thermal imaging. Results We observed that body temperature significantly decreased over days of food restriction, and it was significantly related to the drop in bodyweight (r2=0.8989, p<0.0001). All mice reliably entered torpor daily from day 8 of food restriction which coincided with bodyweight stabilisation at ~85%. We found a strong positive relationship between the magnitude of the decrease of bodyweight and the proportion of mice entering torpor each day (r2=0.8715, p<0.0001). Conclusions Overall, we found that torpor is readily induced in response to food restriction. Considering that hunger is frequently used as a motivational drive in behavioural tasks, it is likely that torpor occurrence is common in such studies, while remaining undetected and unaccounted for. Due to the profound effect of torpor on physiology, it is possible that torpor induction may be confounding subsequent data and represents an important source of variation. We recommend that body temperature is always monitored noninvasively in studies where food restriction is employed, to determine when torpor is occurring, and that torpor history is appropriately controlled for within and across experimental groups.

Summary Endothermic animals in the boreal region experience considerable thermoregulatory costs in winter, especially during inactive periods when high demands cannot be met by increased food intake. This might necessitate a trade‐off between resting thermoregulation and other energetically expensive processes, such as immune function, but this has rarely been investigated. We evaluated how immune activation affected rest‐phase hypothermia (an important energy conservation mechanism in small animals), in wild great tits (Parus major L.) wintering under semi‐natural conditions in southern Sweden. The acute phase response was triggered immediately prior to sunset through intramuscular lipopolysaccharide (LPS, an endotoxin) administration in two contrasting, naturally occurring, thermal regimes (cold, mild). We then noninvasively measured the thermoregulatory response throughout the night using subcutaneously implanted temperature‐sensitive transmitters. Despite the energetic benefits of hypothermia, immunized great tits displayed an attenuated hypothermic response manifested through the onset of fever, possibly at the expense of a higher sustained metabolic rate. In line with this, these birds lost more body mass overnight (but only in mild conditions) and consequently were in worse condition the subsequent morning. Fever expression was remarkably similar in cold and mild conditions, despite substantial variation in the energetic cost for thermoregulation. This suggest that the degree of fever is flexible and represents a trade‐off between the minimum body temperature required to mount an adequate acute phase response and the energy expenditure needed to maintain it. We suggest that while energy conservation and immune function may not always be exclusive activities, costs of immune defences probably constitute an important additive energetic cost during northern winter conditions, sometimes calling for trade‐offs with other important physiological processes to survive the night.

AimsTo assess if ambient temperature-related effects on serum potassium levels impact clinical decision-making.MethodsThis study is an ecological time series consisiting of 1 218 453 adult patients with at least one...

Because of their small size and the high energetic costs of hovering and forward flight, hummingbirds achieve the highest mass-specific metabolic rates known among vertebrates. Rufous hummingbirds (Selasphorus rufus) stop to refuel on floral nectar in subalpine meadows as they migrate south from British Columbia to Mexico. In such habitats they face the challenge of achieving daily net energy gain despite the high energetic costs of flight and thermoregulation at near-freezing morning temperatures. Hummingbirds provided with 15 or 20% sucrose while subjected to these conditions for 4 h in the laboratory did not remain in energy balance and lost mass. However, they achieved energy balance or net energy gain on 30% sucrose. Because these sucrose concentrations are within the range observed in the nectar of hummingbird-visited flowers, the results suggest that the energetic cost of thermoregulation may influence the coevolution of hummingbirds and flowers. Hummingbirds maintaining energy balance at low ambient temperature via high foraging frequencies and high rates of energy intake can sustain average metabolic rates of about 250 W/kg over a 4-h period. These are the highest metabolic rates known among vertebrates at which rates of dietary energy intake equal rates of energy expenditure.

Given the current and future threats to Asian elephants (Elephas maximus), maintaining a sustainable ex situ population is crucial for the longevity of the species. Using Infrared Thermography (IRT), thermoregulation of Asian elephants at low ambient temperatures was examined. Thermal images were taken at 15 min intervals over 60–90-min observation periods, once weekly, during January and February 2022. A total of 374 images were examined from 10 Asian elephants, which varied from 1 to 56 years of age. Data from thermograms of the ear and body were interpreted in view of weight, age and behavior. Variability in surface temperature was found most frequently in the ears, occasionally presenting as thermal windows—areas with dense underlying blood supply that aid in heat exchange. Thermal windows occurred most frequently in the distal, then medial, regions of the ear. The pattern of appearance of thermal windows in the ear provides support that the increase of blood flow is utilized as a method of warming. This preliminary study provides key insight into Asian elephant thermoregulation, suggesting that the species may be more well-adapted to lower ambient temperatures than previously thought.

In nature, photoperiod signals environmental seasonality and is a strong selective “zeitgeber” that synchronizes biological rhythms. For animals facing seasonal environmental challenges and energetic bottlenecks, daily torpor and hibernation are two metabolic strategies that can save energy. In the wild, the dwarf lemurs of Madagascar are obligate hibernators, hibernating between 3 and 7 months a year. In captivity, however, dwarf lemurs generally express torpor for periods far shorter than the hibernation season in Madagascar. We investigated whether fat-tailed dwarf lemurs (Cheirogaleus medius) housed at the Duke Lemur Center (DLC) could hibernate, by subjecting 8 individuals to husbandry conditions more in accord with those in Madagascar, including alternating photoperiods, low ambient temperatures, and food restriction. All dwarf lemurs displayed daily and multiday torpor bouts, including bouts lasting ~ 11 days. Ambient temperature was the greatest predictor of torpor bout duration, and food ingestion and night length also played a role. Unlike their wild counterparts, who rarely leave their hibernacula and do not feed during hibernation, DLC dwarf lemurs sporadically moved and ate. While demonstrating that captive dwarf lemurs are physiologically capable of hibernation, we argue that facilitating their hibernation serves both husbandry and research goals: first, it enables lemurs to express the biphasic phenotypes (fattening and fat depletion) that are characteristic of their wild conspecifics; second, by “renaturalizing” dwarf lemurs in captivity, they will emerge a better model for understanding both metabolic extremes in primates generally and metabolic disorders in humans specifically.

When the body temperature of a small neonate falls below 35 degrees C, lassitude can be noted; severe derangements of cardiovascular, renal, hepatic, immunological, and hematological systems may also occur depending in part on the duration and severity of hypothermia. Diagnosis requires a low-reading thermometer, lacking which the diagnosis can be suspected, but most often is missed. Fatal cases of diagnosed cold injury commonly have terminal pneumonia or sepsis. Prevention involves identification and home visits to high-risk infants; intensive care of those with the diagnosis at Soroka Hospital Medical Center has reduced the case-fatality rate from 30% in 1971 to 3% in 1988-1989. During the same period in our region, the proportion of neonatal deaths occurring in winter months of December, January, and February has dropped from 55 to 27%. The expected proportion is 25%. We hypothesize that excess neonatal mortality during winter months, especially due to pneumonia and sepsis or sudden infant death syndrome (SIDS) is an indicator of missed cold injury syndrome. A preliminary evaluation was made form U.S. data by state, provided by the National Center for Health Statistics, which records no fatalities from cold injury during 1986. Contrasted with this are 26 cold injury deaths in Israel for 1977-1980. In the U.S., though, excess winter neonatal deaths in 1986 from SIDS, pneumonia, and sepsis are reported.(ABSTRACT TRUNCATED AT 250 WORDS)ImagesFIGURE 3.

This study use miniature temperature-sensitive data loggers to record core body temperature (Tb) in Lemniscomysbarbarus, a diurnal Muridae rodent living in Africa. The work shows the existence of a strong and bimodal daily Tb rhythm in this species whose external synchronizer is the light-dark cycle; it’s also confirmed the diurnal and photoperiodic character of this animal. The highest values of Tb were registered during the light-phase in anti-phase with the nocturnal species. In the experimental conditions of this work Lemniscomysbarbarus do not express the phenomenon of diurnal torpor. Nevertheless, this characteristic mechanism of energy saving in small-sized mammals could be appearing by the association of the combined effects of short photoperiod, low ambient temperature and limited food supply.

Effects of Streptozocin-Induced Diabetes and Food Restriction on Quantities and Source of T4 and T3 in Rat Tissues

Dietary energy shortage and ethanol intake in golden hamsters

Lack of agreement among analysers of infrared thermal images in the temperature of eye regions in sheep