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It costs to be clean and fit: energetics of comfort behavior in breeding-fasting penguins.

Viblanc VA, Mathien A, Saraux C, Viera VM, Groscolas R - PLoS ONE (2011)

Bottom Line: Understanding the adaptive value of comfort behavior would benefit from knowledge on the energy costs animals are willing to pay to maintain it, particularly under situations of energy constraints, e.g., during fasting.It shows that although breeding on a tight energy budget, king penguins devote a substantial amount of time and energy to comfort behavior.Such findings underline the importance of comfort behavior for the fitness of colonial seabirds.

View Article: PubMed Central - PubMed

Affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, Strasbourg, France. vincent.viblanc@iphc.cnrs.fr

ABSTRACT

Background: Birds may allocate a significant part of time to comfort behavior (e.g., preening, stretching, shaking, etc.) in order to eliminate parasites, maintain plumage integrity, and possibly reduce muscular ankylosis. Understanding the adaptive value of comfort behavior would benefit from knowledge on the energy costs animals are willing to pay to maintain it, particularly under situations of energy constraints, e.g., during fasting. We determined time and energy devoted to comfort activities in freely breeding king penguins (Aptenodytes patagonicus), seabirds known to fast for up to one month during incubation shifts ashore.

Methodology/principal findings: A time budget was estimated from focal and scan sampling field observations and the energy cost of comfort activities was calculated from the associated increase in heart rate (HR) during comfort episodes, using previously determined equations relating HR to energy expenditure. We show that incubating birds spent 22% of their daily time budget in comfort behavior (with no differences between day and night) mainly devoted to preening (73%) and head/body shaking (16%). During comfort behavior, energy expenditure averaged 1.24 times resting metabolic rate (RMR) and the corresponding energy cost (i.e., energy expended in excess to RMR) was 58 kJ/hr. Energy expenditure varied greatly among various types of comfort behavior, ranging from 1.03 (yawning) to 1.78 (stretching) times RMR. Comfort behavior contributed 8.8-9.3% to total daily energy expenditure and 69.4-73.5% to energy expended daily for activity. About half of this energy was expended caring for plumage.

Conclusion/significance: This study is the first to estimate the contribution of comfort behavior to overall energy budget in a free-living animal. It shows that although breeding on a tight energy budget, king penguins devote a substantial amount of time and energy to comfort behavior. Such findings underline the importance of comfort behavior for the fitness of colonial seabirds.

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Heart rate increase during an episode of comfort behavior in an incubating king penguin.Shadowed zones delimit pre- and post-comfort resting periods and comfort behavior, respectively, whereas the white zone delimits the recovery period. Dotted lines give average HR during comfort behavior and recovery period, respectively, whereas the dashed lined gives average HR during pre- and post-comfort resting periods.
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pone-0021110-g001: Heart rate increase during an episode of comfort behavior in an incubating king penguin.Shadowed zones delimit pre- and post-comfort resting periods and comfort behavior, respectively, whereas the white zone delimits the recovery period. Dotted lines give average HR during comfort behavior and recovery period, respectively, whereas the dashed lined gives average HR during pre- and post-comfort resting periods.

Mentions: Energy expenditure during comfort episodes (both for estimate 2 of global comfort and for specific comfort behaviors) was determined according to [44] and as illustrated in Fig. 1. It was the energy spent in excess to resting metabolic rate (RMR) during comfort behavior plus the potential recovery phase. RMR was calculated from resting HR (mean of pre- and post-comfort resting HR). Comfort HR was the mean HR during comfort behaviors and recovery HR was the mean HR during the recovery phase. Comfort behaviors ended when the bird settled back into resting posture and the recovery phase ended when HR returned to resting levels. The recovery phase lasted on average 0.5±0.1 min (from 0 to 5.3 min, N = 192). Excess HR during comfort behaviors was calculated as [(comfort HR – resting HR)×comfort duration]/resting HR [44] and corresponded to the time that would be required for the number of heart beats in excess to occur at the resting HR level [45]. The same calculation was done for the recovery phase, using recovery HR, and the total excess due to a comfort episode was the sum of excess during comfort plus recovery. The energy cost of a comfort episode (kJ) was calculated as: excess in time (min)×RMR (kJ/hr). Dividing the cost of the episode by its duration (min) yielded an energy cost in kJ/hr.


It costs to be clean and fit: energetics of comfort behavior in breeding-fasting penguins.

Viblanc VA, Mathien A, Saraux C, Viera VM, Groscolas R - PLoS ONE (2011)

Heart rate increase during an episode of comfort behavior in an incubating king penguin.Shadowed zones delimit pre- and post-comfort resting periods and comfort behavior, respectively, whereas the white zone delimits the recovery period. Dotted lines give average HR during comfort behavior and recovery period, respectively, whereas the dashed lined gives average HR during pre- and post-comfort resting periods.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139590&req=5

pone-0021110-g001: Heart rate increase during an episode of comfort behavior in an incubating king penguin.Shadowed zones delimit pre- and post-comfort resting periods and comfort behavior, respectively, whereas the white zone delimits the recovery period. Dotted lines give average HR during comfort behavior and recovery period, respectively, whereas the dashed lined gives average HR during pre- and post-comfort resting periods.
Mentions: Energy expenditure during comfort episodes (both for estimate 2 of global comfort and for specific comfort behaviors) was determined according to [44] and as illustrated in Fig. 1. It was the energy spent in excess to resting metabolic rate (RMR) during comfort behavior plus the potential recovery phase. RMR was calculated from resting HR (mean of pre- and post-comfort resting HR). Comfort HR was the mean HR during comfort behaviors and recovery HR was the mean HR during the recovery phase. Comfort behaviors ended when the bird settled back into resting posture and the recovery phase ended when HR returned to resting levels. The recovery phase lasted on average 0.5±0.1 min (from 0 to 5.3 min, N = 192). Excess HR during comfort behaviors was calculated as [(comfort HR – resting HR)×comfort duration]/resting HR [44] and corresponded to the time that would be required for the number of heart beats in excess to occur at the resting HR level [45]. The same calculation was done for the recovery phase, using recovery HR, and the total excess due to a comfort episode was the sum of excess during comfort plus recovery. The energy cost of a comfort episode (kJ) was calculated as: excess in time (min)×RMR (kJ/hr). Dividing the cost of the episode by its duration (min) yielded an energy cost in kJ/hr.

Bottom Line: Understanding the adaptive value of comfort behavior would benefit from knowledge on the energy costs animals are willing to pay to maintain it, particularly under situations of energy constraints, e.g., during fasting.It shows that although breeding on a tight energy budget, king penguins devote a substantial amount of time and energy to comfort behavior.Such findings underline the importance of comfort behavior for the fitness of colonial seabirds.

View Article: PubMed Central - PubMed

Affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, Strasbourg, France. vincent.viblanc@iphc.cnrs.fr

ABSTRACT

Background: Birds may allocate a significant part of time to comfort behavior (e.g., preening, stretching, shaking, etc.) in order to eliminate parasites, maintain plumage integrity, and possibly reduce muscular ankylosis. Understanding the adaptive value of comfort behavior would benefit from knowledge on the energy costs animals are willing to pay to maintain it, particularly under situations of energy constraints, e.g., during fasting. We determined time and energy devoted to comfort activities in freely breeding king penguins (Aptenodytes patagonicus), seabirds known to fast for up to one month during incubation shifts ashore.

Methodology/principal findings: A time budget was estimated from focal and scan sampling field observations and the energy cost of comfort activities was calculated from the associated increase in heart rate (HR) during comfort episodes, using previously determined equations relating HR to energy expenditure. We show that incubating birds spent 22% of their daily time budget in comfort behavior (with no differences between day and night) mainly devoted to preening (73%) and head/body shaking (16%). During comfort behavior, energy expenditure averaged 1.24 times resting metabolic rate (RMR) and the corresponding energy cost (i.e., energy expended in excess to RMR) was 58 kJ/hr. Energy expenditure varied greatly among various types of comfort behavior, ranging from 1.03 (yawning) to 1.78 (stretching) times RMR. Comfort behavior contributed 8.8-9.3% to total daily energy expenditure and 69.4-73.5% to energy expended daily for activity. About half of this energy was expended caring for plumage.

Conclusion/significance: This study is the first to estimate the contribution of comfort behavior to overall energy budget in a free-living animal. It shows that although breeding on a tight energy budget, king penguins devote a substantial amount of time and energy to comfort behavior. Such findings underline the importance of comfort behavior for the fitness of colonial seabirds.

Show MeSH
Related in: MedlinePlus