Avian Physiology

Dawson, William R.

doi:10.1146/annurev.ph.37.030175.002301

Cited by 25 publications

(8 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although seabird core body temperatures generally range between 36 and 40 °C at rest (Lustick 1984;Prinzinger et al 1991), at high activity levels this can increase to 44 °C in some species (Prinzinger et al 1991), and much of the variability in body temperature can be explained by size (McNab 1966) and ecology (Ellis 1984;Ellis & Gabrielsen 2002). Thermogenesis in flight is much greater because the metabolic rate generally increases between 2 and 11 times basal levels (Dawson 1975;Ellis 1984). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 Thermal demands of climate on endotherms Thus, small, highly-active species (e.g.…”

Section: Metabolic Heat Generationmentioning

confidence: 99%

“…Furness 1988), which might inhibit convective heat loss. In addition, by increasing blood flow to the legs and feet, and by vasodilation, convective heat loss from these structures is improved (Steen & Steen 1965;Dawson 1975Dawson , 1982, especially during flight (Baudinette et al 1976) or if the areas are concurrently shaded from radiative heat gain (Howell & Bartholomew 1961). Respiratory, non-evaporative heat loss, such as the warming and subsequent expiration of inspired air, may also be important in some circumstances (Dawson & Whittow 2000).…”

Section: Convectionmentioning

confidence: 99%

See 1 more Smart Citation

Direct impacts of climatic warming on heat stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints

Oswald

Arnold

2012

Integrative Zoology

View full text Add to dashboard Cite

There is now abundant evidence that contemporary climatic change has indirectly affected a wide-range of species by changing trophic interactions, competition, epidemiology and habitat. However, direct physiological impacts of changing climates are rarely reported for endothermic species, despite being commonly reported for ectotherms. We review the evidence for changing physiological constraints on endothermic vertebrates at high temperatures, integrating theoretical and empirical perspectives on the morphology, physiology and behavior of marine birds. Potential for increasing heat stress exposure depends on changes in multiple environmental variables, not just air temperature, as well as organism-specific morphology, physiology and behavior. Endotherms breeding at high latitudes are vulnerable to the forecast, extensive temperature changes because of the adaptations they possess to minimize heat loss. Low-latitude species will also be challenged as they currently live close to their thermal limits and will likely suffer future water shortages. Small, highly-active species, particularly aerial foragers, are acutely vulnerable as they are least able to dissipate heat at high temperatures. Overall, direct physiological impacts of climatic change appear underrepresented in the published literature, but available data suggest they have much potential to shape behavior, morphology and distribution of endothermic species. Coincidence between future heat stress events and other energetic constraints on endotherms remains largely unexplored but will be key in determining the physiological impacts of climatic change. Multi-scale, biophysical modeling, informed by experiments that quantify thermoregulatory responses of endotherms to heat stress, is an essential precursor to urgently-needed analyses at the population or species level.

show abstract

Section: Metabolic Heat Generationmentioning

confidence: 99%

Section: Convectionmentioning

confidence: 99%

Direct impacts of climatic warming on heat stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints

Oswald

Arnold

2012

Integrative Zoology

View full text Add to dashboard Cite

show abstract

“…Thermoregulatory capacity in birds depends on the functional maturity of the skeletal muscles, which, apparently, are the primary source of heat production in response to cold stress in both adult (Dawson 1975;Hohtola and Stevens 1986) and young (Olson 1994;Marjoniemi and Hohtola 1999) birds. However, development of functional maturity also imposes costs.…”

Section: Introductionmentioning

confidence: 99%

Catabolic Capacity of the Muscles of Shorebird Chicks: Maturation of Function in Relation to Body Size

Krijgsveld¹,

Olson²,

Ricklefs³

2001

Physiological and Biochemical Zoology

View full text Add to dashboard Cite

Newly hatched precocial chicks of arctic shorebirds are able to walk and regulate their body temperatures to a limited extent. Yet, they must also grow rapidly to achieve independence before the end of the short arctic growing season. A rapid growth rate may conflict with development of mature function, and because of the allometric scaling of thermal relationships, this trade-off might be resolved differently in large and small species. We assessed growth (mass) and functional maturity (catabolic enzyme activity) in leg and pectoral muscles of chicks aged 1-16 d and adults of two scolopacid shorebirds, the smaller dunlin (Calidris alpina: neonate mass 8 g, adult mass 50 g) and larger whimbrel (Numenius phaeopus; neonate mass 34 g, adult mass 380 g). Enzyme activity indicates maximum catabolic capacity, which is one aspect of the development of functional maturity of muscle. The growth rate-maturity hypothesis predicts that the development of catabolic capacity should be delayed in faster-growing muscle masses. Leg muscles of both species were a larger proportion of adult size at hatching and grew faster than pectoral muscles. Pectoral muscles grew more rapidly in the dunlin than in the whimbrel, whereas leg muscles grew more rapidly in the whimbrel. In both species and in both leg and pectoral muscles, enzyme activities generally increased with age, suggesting increasing functional maturity. Levels of citrate synthase activity were similar to those reported for other species, but l-3-hydroxyacyl-CoA-dehydrogenase and pyruvate kinase (PK) activities were comparatively high. Catabolic capacities of leg muscles were initially high compared to those of pectoral muscles, but with the exception of glycolytic (PK) capacities, these subsequently increased only modestly or even decreased as chicks grew. The earlier functional maturity of the more rapidly growing leg muscles, as well as the generally higher functional maturity in muscles of the more rapidly growing dunlin chicks, contradicts the growth rate-maturity function trade-off and suggests that birds have considerable latitude to modify this relationship. Whimbrel chicks, apparently, can rely on allometric scaling of power requirements for locomotion and the thermal inertia of their larger mass to reduce demands on their muscles, whereas dunlin chicks require muscles with higher metabolic capacity from an earlier age. Thus, larger and smaller species may adopt different strategies of growth and tissue maturation.

show abstract

“…When not actively foraging, they respond to cooling by shivering to generate heat (Dawson 1975;Hohtola and Stevens 1986), but often neither mechanism can produce enough heat to prevent body cooling (Ricklefs and Williams 2003). Therefore, foraging is regularly interrupted by periods of brooding by the parent, during which body temperature is restored to higher levels.…”

Section: Introductionmentioning

confidence: 99%

Daily energy expenditure in precocial shorebird chicks: smaller species perform at higher levels

2012

View full text Add to dashboard Cite

We measured daily energy expenditure (DEE) during the development periods of precocial chicks of five species of Arctic shorebirds spanning a broad range in size, in order to investigate the relationships between DEE, body size, and growth rate. We also quantified the effect of weather conditions on the energy expenditure of chicks to establish the impact of cold arctic weather on their time and energy budgets. We used the doubly labeled water method to measure DEE at ambient temperatures in an outside enclosure on the subarctic tundra at Churchill, Manitoba, Canada. Growth rate was highest in the smallest species, and in general decreased with adult size, as shown by the decrease in growth rate constant and later inflection point with increasing adult body mass. DEE ranged from 14 kJ day -1 in young chicks of the smaller species to 365 kJ day -1 in older chicks of the larger species. From hatching onward, DEE of shorebirds was high compared to DEE of chicks of altricial species, reflecting the high costs of locomotion and thermoregulation, and mass-specific DEE increased rapidly to adult levels. Chicks of smaller species metabolized more energy per unit mass and functioned at higher multiples of resting metabolic rate than chicks of larger species. As chicks of smaller species also had higher growth rates, and thus simultaneously invested in growth and mature function, it seems that shorebird chicks can adjust total metabolizable energy as well as its relative allocation between investment in growth and mature function. DEE was similar to cold-induced peak metabolic rates achieved by shivering thermogenesis. Because chicks were motionless during laboratory metabolism measurements, the relatively high level of DEE compared to these metabolic rates suggests that locomotion produces similar amounts of heat as shivering. Ambient temperature did not affect DEE in outdoor pens, although higher wind speed resulted in slightly increased energy expenditure. Heat produced by locomotion is possibly sufficient to sustain thermoregulation under local environments. Furthermore, when ambient temperatures are low, chicks spend more time brooding and less time foraging, which presumably counters the tendency to increase thermogenesis in response to cold.

show abstract

Avian Physiology

Cited by 25 publications

References 51 publications

Direct impacts of climatic warming on heat stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints

Direct impacts of climatic warming on heat stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints

Catabolic Capacity of the Muscles of Shorebird Chicks: Maturation of Function in Relation to Body Size

Daily energy expenditure in precocial shorebird chicks: smaller species perform at higher levels

Contact Info

Product

Resources

About