Intraspecific variation in avian pectoral muscle mass: constraints on maintaining manoeuvrability with increasing body mass

Dietz, Maurine W.; Piersma, Theunis; Hedenström, Anders; Brugge, Maarten

doi:10.1111/j.1365-2435.2006.01234.x

Cited by 82 publications

(82 citation statements)

References 54 publications

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“…constant body mass throughout winter as a consequence of higher wing loading, in order to minimise flight costs and maintain manoeuvrability (Pennycuick, 1975;Lindström et al, 2000;Lind and Jakobsson, 2001;Dietz et al, 2007). The positive relationship between pectoral muscle size and maximal thermogenic capacity confirms previous findings (O 'Connor, 1995;Marjoniemi and Hohtola, 1999;Cooper, 2002;Vézina et al, 2007;.…”

Section: Discussionsupporting

confidence: 80%

Phenotype manipulations confirm the role of pectoral muscles and haematocrit in avian maximal thermogenic capacity

Petit

Vézina

2013

Journal of Experimental Biology

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In small resident bird species living at northern latitudes, winter cold acclimatization is associated with an increase in pectoral muscle size and haematocrit level, and this is thought to drive the seasonal increase in summit metabolic rate (Ṁ sum , a measure of maximal shivering thermogenic capacity). However, evidence suggesting that pectoral muscle size influences Ṁ sum is correlational and the link between haematrocrit level and Ṁ sum remains to be demonstrated. We experimentally tested the relationship between pectoral muscle size and Ṁ sum by manipulating muscle size using a feather clipping protocol in free-living wintering black-capped chickadees (Poecile atricapillus). This also allowed us to investigate the link between haematocrit and thermogenic capacity. After a first series of measures on all birds, we cut half of the flight feathers of experimental individuals (N=14) and compared their fat and pectoral muscle scores, Ṁ sum and haematocrit level at recapture with their previous measures and with those of control birds (N=17) that were captured and recaptured at comparable times. Results showed that: (1) experimental birds developed larger pectoral muscles than control individuals and (2) mass-independent Ṁ sum was up to 16% higher in birds expressing large pectoral muscles. Ṁ sum was also positively correlated with haematocrit, which was not affected by the experimental manipulation. These findings demonstrate that, for a given body mass, large pectoral muscles are associated with a higher Ṁ sum in black-capped chickadees and that oxygen carrying capacity likely supports thermogenesis in this species.

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Section: Discussionsupporting

confidence: 80%

Phenotype manipulations confirm the role of pectoral muscles and haematocrit in avian maximal thermogenic capacity

Petit

Vézina

2013

Journal of Experimental Biology

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“…Yet, the relationship with change in body mass remained nonsignificant in birds experiencing variable conditions, when considering individual effects and repeated measures. A likely explanation for this finding is provided by a recent study performed by Dietz et al (23). Using dissection data collected over 21 years (155 islandica Fig.…”

Section: Changes In Body Mass and Pectoral Muscles And Their Effects mentioning

confidence: 97%

Thermogenic side effects to migratory predisposition in shorebirds

Vézina

Jalvingh²,

Dekinga³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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.-In the calidrine sandpiper red knot (Calidris canutus), the weeks preceding takeoff for long-distance migration are characterized by a rapid increase in body mass, largely made up of fat but also including a significant proportion of lean tissue. Before takeoff, the pectoral muscles are known to hypertrophy in preparation for endurance flight without any specific training. Because birds facing cold environments counterbalance heat loss through shivering thermogenesis, and since pectoral muscles represent a large proportion of avian body mass, we asked the question whether muscle hypertrophy in preparation for long-distance endurance flight would induce improvements in thermogenic capacity. We acclimated red knots to different controlled thermal environments: 26°C, 5°C, and variable conditions tracking outdoor temperatures. We then studied within-individual variations in body mass, pectoral muscle size (measured by ultrasound), and metabolic parameters [basal metabolic rate (BMR) and summit metabolic rate (M sum)] throughout a 3-mo period enclosing the migratory gain and loss of mass. The gain in body mass during the fattening period was associated with increases in pectoral muscle thickness and thermogenic capacity independent of thermal acclimation. Regardless of their thermal treatment, birds showing the largest increases in body mass also exhibited the largest increases in M sum. We conclude that migratory fattening is accompanied by thermoregulatory side effects. The gain of body mass and muscle hypertrophy improve thermogenic capacity independent of thermal acclimation in this species. Whether this represents an ecological advantage depends on the ambient temperature at the time of fattening. muscle mass; summit metabolic rate; basal metabolic rate; thermogenic capacity; phenotypic flexibility LONG-DISTANCE MIGRATION IN birds is an energy-demanding phenomenon that leads to remarkable physiological adjustments that are among the best-known examples of phenotypic flexibility in higher vertebrates (52,59). In birds preparing for long-distance flights, the period of migratory fattening often involves a reorganization of specific physiological systems, including metabolic changes ranging from the level of the cell (24,42,43,44,46,65,66) to that of the whole animal (6,33,39,79). In the weeks preceding takeoff, as well as during a refueling stopover, birds have to maximize energy input to accumulate the fat stores necessary to fuel their nonstop flight. To do so, they enter a hyperphagic phase with extreme energy assimilation rates (34,38,60

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“…The flight muscles change in parallel with overall body mass (e.g. Lindström et al 2000), but the increase does not match the increase in power requirements in the red knot Calidris canutus (Dietz et al 2007). When birds are very fat, the power margin is reduced compared with when they are lighter, suggesting that they are trading escape flight capacity (predation risk) against migratory flight economy.…”

Section: What Is the Evidence For Time-selected Migration?mentioning

confidence: 99%

Adaptations to migration in birds: behavioural strategies, morphology and scaling effects

Hedenström

2007

Phil. Trans. R. Soc. B

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217

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The annual life cycle of many birds includes breeding, moult and migration. All these processes are time and energy consuming and the extent of investment in any one may compromise the others. The output from breeding is of course the ultimate goal for all birds, while the investment in moult and migration should be selected so that lifetime fitness is maximized. In particular, long-distance migrants breeding at high latitudes face severe time pressures, which is a probable reason why natural selection has evolved efficient behaviours, physiological and morphological adaptations allowing the maximum possible migration speed. Optimal migration theory commonly assumes time minimization as an overall strategy, but the minimization of energy cost and predation risk may also be involved. Based on these assumptions, it is possible to derive adaptive behaviours such as when and at which fuel load a stopover site should be abandoned. I review some core components of optimal migration theory together with some key predictions. A review of accumulated empirical tests of the departure rule indicates that time minimization is an important component of the overall migration strategy, and hence gives support to the assumption about time-selected migration. I also briefly discuss how the optimal policy may be implemented by the bird by applying a set of simple rules. The time constraints on migrants increase with increasing body size. Some consequences of this are discussed.

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Intraspecific variation in avian pectoral muscle mass: constraints on maintaining manoeuvrability with increasing body mass

Cited by 82 publications

References 54 publications

Phenotype manipulations confirm the role of pectoral muscles and haematocrit in avian maximal thermogenic capacity

Phenotype manipulations confirm the role of pectoral muscles and haematocrit in avian maximal thermogenic capacity

Thermogenic side effects to migratory predisposition in shorebirds

Adaptations to migration in birds: behavioural strategies, morphology and scaling effects

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