George C. West

Daily and seasonal variation in metabolic response to cold during rest and forced exercise in the common redpoll

Abstract Metabolic measurements of common redpolls ( Carduelis = Acanthis flammea ) acclimatized to outdoor conditions throughout the year at Fairbanks, Alaska, have shown that: 1. 1. Day-night (circadian) differences in the rate of oxygen consumption at various ambient temperatures, and changes in the slope of the metabolism vs. temperature relationship are more pronounced during winter than during summer. 2. 2. Heat production at very low temperatures (below −30°C) measured during daytime at rest and during forced exercise is significantly higher during winter than during summer. Higher rates of oxygen consumption are associated with higher body temperatures under both conditions. From the results it is concluded that the high capacity for heat production during the day as well as the reduced heat loss (increased insulation) during the night are the principal physiological factors permitting survival of the common redpoll at extreme low temmperatures in subarctic winter.

Seasonal differences in resting metabolic rate of Alaskan ptarmigan

Abstract 1. 1. The resting metabolic rates at thermal neutrality of willow ptarmigan acclimatized to summer and winter and of rock ptarmigan acclimatized to winter of 78·84, 70·50 and 70·84 kcal/bird per day respectively, are all higher than predicted by several body weight-metabolic rate equations. 2. 2. The slope of the metabolic rate-ambient temperature line below thermal neutrality was steeper in summer than in winter in willow ptarmigan. The critical temperature of summer birds was 7·7°C and of winter birds, -6·3°C, lower than for any bird species thus far tested. 3. 3. The slope of the metabolic rate-ambient temperature line below thermal neutrality for winter rock ptarmigan was similar to that of winter willow ptarmigan and the critical temperature was -1·3°C. 4. 4. Alaska willow and rock ptarmigan are capable of maintaining their normal body temperature at any ambient temperature which they might encounter in arctic Alaska by a combination of excellent insulation and adequate metabolic capacity.

Fatty acid composition of caribou bone marrow.

Abstract 1. 1. The fatty acid composition of caribou ( Rangifer tarandus ) leg bone marrow decreased in saturation distally, which corresponds with changes observed in melting point. 2. 2. The major changes were in (a) oleic acid (C 18-1 ) which increased from 42 per cent at the head of the femur and humerus to 74 per cent in the phalanges; (b) stearic acid (C 18 ) which decreased from 21 per cent to 6 per cent; and (c) palmitic acid (C 18 ) which decreased from 26 per cent to 13 per cent in the same tissue.

Cecal Fermentation in the Willow Ptarmigan

Gallinaceous birds have two relatively large ceca arising from the junction of the small and the large intestines. The size of these organs has led to speculation regarding their role in digestion of cellulose and other resistant materials (Farner 1960). Suomalainen and Arhimo (1945) showed by the use of enrichment cultures that cellulose fermentation could be induced by inoculation with cecal content from several grouse species, including the Willow Ptarmigan, Lagopus lagopus. The responsible bacteria were not isolated.

The effect of acclimation and acclimatization on the resting metabolic rate of the common redpoll

Abstract 1. 1. Average resting metabolic rates at thermal neutrality of common redpolls (Acanthis = Carduelis flammea) tested in the dark during the day did not differ among all conditions of acclimation (20°C, 0°C, t20°C and light: dark cycles of 12 : 12 and 20 : 4 hr) and acclimatization to season (6·84 kcal/bird per 24 hr) except in winter (9·47 kcal/bird per 24 hr). The former value agrees with the prediction of Aschoff & Pohl (1969). 2. 2. There were statistically significant differences in slope or level of the regression lines of metabolic rate vs. ambient temperature among most acclimation groups but the only trend evident was that metabolic rates of birds acclimated to short photoperiods (4 : 20) at moderate temperatures (20°C) were elevated in the cold in an amount equivalent to that of those either acclimatized to winter or acclimated to cold (−20°C). 3. 3. Winter and summer metabolic rates were higher than those in spring and fall at low ambient temperatures indicating either an increased requirement for metabolic capacity in winter and summer or conversely a decreased resting energy requirement in spring and fall. 4. 4. Heat loss coefficients of redpolls below the critical temperature (0·819 cal/g per hr per °C) were lower than those measured on dead birds of the same body weight (Herreid & Kessel, 1967). 5. 5. The hypothesis that the slope of the metabolic rate vs. temperature regression line of birds tested for short periods of time (ca. 1 hr) at the temperature of acclimation would be flat as is found in studies utilizing the food consumption method (several days) was not substantiated for the small (14 g) redpoll. However, when applied to the larger (550 g) willow ptarmigan (Lagopus lagopus) the hypothesis held true.

Fat content, fatty acid composition and estimates of energy metabolism of adélie penguins (Pygoscelis adeliae) during the early breeding season fast

Abstract 1. 1. Adelie penguins (Pygoscelis adeliae) breeding at Cape Crozier, Antarctica, arrive in the colony from the sea in October at the beginning of the austral summer. Both sexes fast while on the breeding colony for 3–6 weeks before returning to the sea to feed. 2. 2. Six individuals collected during the first fast period showed decreased blubber thickness and a linearly corresponding decrease in ether extractable fat with time after arrival in the breeding area. Birds contained about 45 per cent of dry weight as fat upon arrival, and in a typical incubation, males decreased to about 20 per cent after day 27. 3. 3. The decrease in fat represents approximately 56 g of fat used per day by fasting male Adelies for the 27-day period. On the basis of this value, it has been estimated that 490 kcal/bird per day approximates energy demands for these fasting birds during the early part of the breeding season. 4. 4. Fatty acid compositions of total ether extractable lipids, subcutaneous fat and abdominal depot fat did not differ significantly except in a few of the long-chain acids. Depot fat fatty acids of normal breeding birds did not change significantly from arrival on the colony to day 27. 5. 5. Proportions of fatty acids in Adelie penguin depot fat correspond with the proportions of fatty acids in their normal diet of krill (Euphausia superba).

The annual lipid cycle and feeding behavior of Alaskan redpolls

SummaryTotal lipids were extracted from 161 redpolls (Acanthis spp.) collected each month of the year from October 1962 to September 1963, in interior Alaska. A lipid index (Weight of ether extract x100/live body weight) was calculated for each sample. Lipids were also extracted from sections of pectoral muscle, livers and hearts representing each month.Body weight and lipid index were significantly positively correlated being highest in January and lowest in September. Total lipid content was significantly inversely correlated with air temperature; the high autumn and spring pre-migratory lipid peaks of migratory species were only weakly expressed in the redpolls. Liver lipid showed a significant annual variation being highest in December and lowest in August, while lipid from heart and pectoral muscle did not vary seasonally.Five birds were held in captivity during spring and summer at a constant temperature of 22°C. Food consumption was 5.1 g/day or 22.4 kcal. The caloric value of the most extensively utilized natural food, birch seed (Betula papyrifera), was determined (5.4–5.5 kcal/g dry wt). When esophageal diverticulae are full (2.0 g wet wt) of birch seeds, the resulting energy yield may sustain an individual for only a fraction of a 24 h winter day in contrast to other arctic herbivores (e.g. ptarmigan, Lagopus sp.) in which a full crop may suffice for the full 24 h period.

Fatty acid composition of Dall sheep bone marrow.

Abstract 1. 1. The fatty acid composition of Dall sheep (Ovis dalli) front leg bone marrow decreased in saturation distally with the major changes occurring in the radius. 2. 2. Oleic acid (C18:1) increased from 44% in the upper humerus to 70% in the phalanges while palmitic (C16) and stearic (C18) acids decreased from 19 and 18% to 13 and 5% respectively over the length of the leg.

Latitudinal and population specific differences in timing of daily and seasonal functions in redpolls (Acanthis flammea)

Summary1.The daily (circadian) rhythm of activity and rest of common redpolls (Acanthis f. flammea L.) from 65°N lat. was measured for about one year in individuals outdoors at two latitudes (48° and 65°N). During winter at both latitudes, activity-time (α) of common redpolls approximated the duration of daylight (including civil twilights); onset of activity, however, occurred at lower light intensities than end of activity. During mid-summer, a rest-time (p) of ca. 5 h was maintained at both latitudes. During the times of spring and fall migration (extending into summer or winter, respectively), common redpolls showed nightly unrest or shifted their onset of daily activity into the pre-dawn hours.2.Redpolls of two subspecies (A. f. flammea and A. f. cabaret Müller) resident at different latitudes (ca. 65° and 49°N) were maintained and measured under the same light conditions at 48°N lat. The two populations showed significant differences in their responses to the same annual changes in day length which included: (i) differences in the timing of the circadian activity rhythm with respect to the daily solar cycle; (ii) differences in the amount and range of seasonal changes in nightly unrest; (iii) differences in the mean level and range of seasonal changes of body weight; and (iv) differences in the timing of postnuptial molt.3.In all experimental groups of redpolls, the highest “precision” (i.e. lowest mean day-to-day variation) in onset and end of activity was observed when both phases occurred during the twilights. The different effects of annually changing light conditions on onset and end of activity with respect to solar time indicated that timing of these two phases of the activity rhythm is independently controlled. It is further indicated that an annually changing sensitivity to light controls the termination of activity in common redpolls, although ambient temperature can modify this response.4.Besides the direct influence of latitude on timing and the amount of changes of various circadian and annual functions throughout the year, the important role of long-term (genetic?) adaptation to the light and temperature conditions prevailing in the respective habitats of redpoll populations is emphasized by the results of this study.

The Spring Migration of Gambel's Sparrows through Southern Yukon Territory

In their study of the spring migration in the Lapland Longspur (Calcarius lapponicus alascensis) through southern Yukon Territory, West et al. (1968a) hypothesized that longspur flocks are temporary associations, changing almost daily in composition. The authors also present evidence that longspurs enter Alaska by several routes: from prairies of southwestern Canada, through the Rocky Mountains, and along the Pacific Coast. To learn whether there is evidence for similar