R. Hissa

Nocturnal hypothermia in fasting Japanese quail: The effect of ambient temperature

Japanese quail were equipped with intraperitoneal transmitters for telemetric measurement of body temperature (Tb) and activity. Food deprivation at + 24 degrees C for four days induced a well-defined nocturnal hypothermic response. The normal day-night difference (about 1 degrees C) in Tb increased 1 degrees C per day, reaching 5 degrees C on the fourth night of fast. Nocturnal motor activity decreased during the fast, while daytime activity first increased and then returned to the original level by the end of the fasting period. A strong correlation between Tb and motor activity was found during scotophase (r = .91) but not during photophase (r = .02). At + 4 degrees C, where food was deprived for two days, the level of hypothermia was not different from that at + 24 degrees C, but birds fasting in the cold reached the hypothermic level more rapidly. In control birds, the decrease in Tb at the beginning of scotophase was independent of ambient temperature. In the combined data, the level of hypothermia correlated strongly with body mass loss (r = .90), which shows that quail can directly or indirectly sense the amount of body energy reserves. This is the first report of hypothermia in a fasting gallinaceous bird. The consistent level of hypothermia at varying ambient temperatures suggests that either nonenergetic costs or phylogenetic constraints prevent deeper hypothermia in cold. Accordingly, the regulation of hypothermia cannot be explained by using only energetic arguments.

Effects of hand-rearing on physiology and anatomy in the grey partridge

Artificial rearing may result in changes in the physiology and anatomy of gallinaceous birds. This may partially explain the poor survival of released birds. To study the effects of hand-rearing on grey partridges Perdix perdix, we measured the anatomical and physiological characteristics of 14 wild and 15 hand-reared partridges. Captive partridges were heavier, had relatively larger breast muscles but relatively lighter hearts and livers than wild birds. Wild birds had longer small intestines, longer caeca and relatively heavier gizzards than hand-reared birds. They also had higher glycogen content and cytochrome-c oxidase activity in the pectoral muscles, indicating their better flying endurance compared to hand-reared birds. The results suggest that captivity results in altered anatomical and physiological characteristics, and hand-reared partridges may therefore be poorly predisposed for an abrupt release into the wild.

The influence of high ambient temperature on thermoregulatory response to intrahypothalamic injections of noradrenaline and serotonin in the pigeon

Abstract1.Pigeons with chronically implanted injection cannula in the hypothalamus were injected with noradrenaline (NA, 10 μg/μl) and 5-hydroxytryptamine (5-HT, 10 μg/μl) at the ambient temperature (Ta) of 38° or 42°C.2.Initial tests at cold (6°C) indicated that birds responded hypothermically to NA and in most instances also to 5-HT.3.Intrahypothalamic injection of NA (10μ/μl) had no appreciable effect on oxygen consumption (VO2), body temperature (Tb), foot temperature (Tf), or heart and respiratory rates at Ta 38°C. The increase of VO2, Tb and Tf noted after similar injection at 42°C was in all probability due to observed excitement and bursts of struggling rather than effects on thermoregulatory mechanisms.4.5-HT (10 μg/μl) injected at Ta 38°C depressed respiratory frequency from panting (600 breaths·min−1) to normal rate (ca. 50·min−1) within 2–4 min. The absence of panting lasted about 10 min, but only a slight increase of VO2, Tb and Tf followed. At Ta 42°C, no notable changes of VO2, Tb and Tf were recorded after 5-HT injection.5.It is concluded that 5-HT has an inhibitory action on neuronal pathway controlling panting activity in the pigeon, but NA seems to be ineffective.

Breeding dispersal and demography of wild and hand-reared grey partridges Perdix perdix in Finland

To evaluate the usefulness of restocking of grey partridge Perdix perdix in marginal ranges we studied survival, spring dispersal and breeding success of wild and released grey partridge females using radio-tracking. Released females had lower survival during the breeding period than wild females. Within the limitation of the small sample size obtained from the released birds surviving till nesting, there was no difference in spring dispersal, nesting chronology, clutch size, and nest predation between wild and released birds. However, wild partridges produced more fledglings per radio-tracked female than released birds. This difference was mainly due to the higher survival rates of wild hens compared to those of released hens before the incubation period. We conclude that due to their poor survival and reproduction output, released birds may have little value in attempts to boost threatened wild populations of the grey partridge, whereas habitat management and predator control could be more useful tools for the preservation of grey partridge populations in marginal regions.

Summer and Winter Temperature Regulation in the Black Grouse Lyrurus tetrix

Metabolic rate and thermal responses to ambient temperatures between -26.5 C and 34.0 C were studied in the adult black grouse in both summer and winter, and in juvenile (70-80 days old) black grouse in early autumn. At an ambient temperature between 0 C and 20 C, the body temperature of the adult grouse was significantly higher in summer (41.3 ± .09 C) than in winter (40.2 ± .14 C). The standard metabolism at thermoneutrality was 6.5 W/kg in summer and 8.2 W/kg in winter, being higher in both seasons than predicted by theoretical equations. The lower critical temperature was 9.5-12.5 C in summer and around 5 C in winter. However, no clear inflection point was seen in the metabolism in winter. The increase in metabolic rate was only 1.7-fold in winter and 2.2-fold in summer when ambient temperature decreased from 30 C to -23 C. At ambient temperatures ranging from 10 C to -23 C the thermal conductance was higher in winter than in summer; in winter, but not in summer, it decreased with decreasing ambient temperature. The assumption is that in winter the black grouse improve their insulation also at ambient temperature far below the lower critical temperature.

Energetics and Development of Temperature Regulation in Capercaillie Tetrao urogallus

Thermoregulatory capacities of newly hatched and developing capercaillie chicks (Tetrao urogallus) were studied. Metabolic rate and body temperature measurements were conducted at ambient temperatures (Ta) between −30 and 37 C. The chicks rely primarily on behavioral thermoregulation. A sudden increase of basal heat production at the age of 4–5 days constitutes an important element in the control of stable body temperature (Tb) and coincides with the gradual elevation of the body temperature and capacity to stimulate thermoregulatory heat production. Chicks 1–3 days old can more than double their metabolic rate at 15 C. There is no evidence of regulatory nonshivering thermogenesis. Consequently, the only way to increase heat production is to stimulate muscular activity either by shivering or by voluntary muscular activity. The most rapid development of thermoregulatory capacity occurs at the age of 7–11 days, which may be correlated with the synergistic maturation of neuronal thermoregulatory control elements and a functional hypothalamichypophysis axis. Since the development of insulation is only gradual during the first weeks of hatching, it plays only a secondary role in comparison with the behavioral means of seeking shelter under the female and an increased basal metabolic rate. Our results support the field observations which indicate that newly hatched capercaillie chicks can tolerate 10–15 C only a few minutes.

Impact of hand-rearing on morphology and physiology of the capercaillie (Tetrao urogallus)

Morphological and physiological disparities between 20 captive and 11 wild capercaillies were determined. Birds, their pectoral and leg muscles, hearts, livers and gizzards were weighed. The length of small intestines and caeca were measured. Haemoglobin, haematocrit, glucose, triglycerides, total protein, uric acid and thyroid hormones as well as the cytochrome c-oxidase activity of the pectoral muscle and heart were determined. The glycogen and protein contents of pectoral and leg muscles and liver were analysed. Chemical composition (water, fat, protein, ash) of muscles and liver was determined. Captive males had heavier pectoral muscles than wild ones. The result was opposite in females. Wild birds had heavier hearts, livers, and gizzards, and also longer small intestines and caeca than captive birds. The cytochrome c-oxidase activity of pectoral muscle and heart was higher in wild than in hand-reared birds. The chemical composition of livers of wild birds differed significantly from that of hand-reared capercaillies. Plasma uric acid and T(4) concentrations were higher in captive than in wild birds. The observed differences in digestive system and liver can result in diminished ability of captive birds to utilise natural food nutrients. Decreased cytochrome c-oxidase activity of hand-reared birds can affect their takeoff and flying capacity and increase their vulnerability to predation. These facts may contribute to the low survival of hand-reared birds after release.

Annual variation in the concentrations of circulating hormones in capercaillie (Tetrao urogallus)

Seasonal variation in the levels of immunoreactive lutropin (LH), follitropin (FSH), prolactin (PRL), corticosterone (B), thyroxine (T4), and triiodothyronine (T3) was measured in the plasma of male and female capercaillies (Tetrao urogallus, Galliformes) in captivity (latitude N 67 degrees). In male capercaillies there was an increase in the concentrations of LH and FSH beginning in March and reaching their maxima in May, which correlated with the nesting period. The concentration of plasma PRL increased from the end of April and reached its highest level simultaneously with the rapid fall of plasma LH and FSH concentrations. It remained elevated until August, Plasma T4 level was depressed after levels of plasma FSH and LH had reached their maxima and was correlated to simultaneous elevation of plasma PRL level. No dramatic seasonal changes in plasma T3 level were noted. In the female capercaillie no marked changes in plasma FSH and LH concentrations were observed. Although four of six females laid eggs only one of them managed to terminate its nesting successfully; five eggs hatched. Changes in prolactin concentration in females parallel those in males. No marked variations were observed in plasma corticosterone concentrations. On the basis of these results it seems probable that captive female capercaillie show depressed gonadotrophin secretion, resulting in unsuccessful nesting. On the other hand it has to be emphasized that gonadotrophin assays may not be sensitive enough, especially in the female, to measure LH and FSH in the volumes of plasma put in the assays.

Shivering and ptiloerection as complementary cold defense responses in the pigeon during sleep and wakefulness

SummaryThe effects of sleep and wakefulness on two autonomic cold defense responses, shivering and ptiloerection, were studied in the pigeon. Shivering (integrated pectoral muscle EMG), axillary and foot temperatures were measured continuously and the magnitude of ptiloerection was estimated by a specially devised feather index (FI) using a TV-monitor. Behavioral signs of sleep and wakefulness were verified by EEG-recordings.In pigeons placed at +4°C, slow-wave sleep was associated with a gradual decline of shivering and a simultaneous increase of FI. Spontaneous bouts of arousal elicited strong bursts of shivering and coincident drops in FI (Fig. 2). Alerting the sleeping pigeons by a standardized stimulus had the same effects as spontaneous arousal, but the changes were more consistent. The stimulus produced behavioral and electrocortical arousal, a 81% increase in shivering intensity, and an almost complete elimination of ptiloerection. A slight vasodilatation of feet and a neglible increase of axillary temperature followed (Fig. 3). The changes in shivering and FI showed a significant negative correlation both during spontaneous and induced bouts of arousal.These results show that ptiloerection is preferentially used for cold defense during sleep, whereas shivering is recruited during periods of arousal. This complementarity of insulative and thermogenic mechanisms may form a physiological basis for explaining some diurnal patterns in avian bioenergetics.

Thermoregulatory effects of peripheral injections of monoamines on the pigeon.

Abstract 1. The effects of peripheral injections of different doses of monoamines were tested in pigeons at different ambient temperatures. 2. It was observed that noradrenaline produced a dose-dependent hypothermia at +6°C and a dose-dependent hyperthermia at +32°C. At the thermoneutral zone of +26°C a slight hyperthermic effect was also seen. 3. Adrenaline also inhibited shivering, lowered oxygen consumption and decreased body temperature at +6°C. 4. Like noradrenaline serotonin also produced either hypothermia at +6°C or hyperthermia at +32°C. 5. The hypothermic effect of norarenaline was totally blocked by phentolamine but not by propranolol. 6. It is suggested that the thermoregulatory effects of peripherally injected monoamines act at thermoregulatory centers in the nervous system.