It Costs to Be Clean and Fit: Energetics of Comfort Behavior in Breeding-Fasting Penguins

), seabirds known to fast for up to one month during incubation shifts ashore.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.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

External pH modulation during the growth of Vibrio tapetis , the aetiological agent of brown ring disease

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The energy cost of global comfort behavior in incubating king penguins.

<p>Relationships between the proportion of time spent in comfort behavior during 15 min periods (C %) and corresponding mean heart rate (HR) level. Data are for 3 males (□, Δ, ○) and 2 females (▪, ▴) with 96 values per individual. General equation for the mixed model is HR (bpm) = 65.89±3.95+0.28±0.02 * C %. (GEE, R² = 0.19, Wald = 167, P<0.001). From the slope of the relationship and the equation relating HR to energy expenditure, the energy cost of comfort behavior was estimated at 61.2 kJ/hr (i.e. 17 W).</p

Heart rate increase during an episode of comfort behavior in an incubating king penguin.

<p>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.</p

The energy cost of specific comfort behaviors in breeding king penguins.

<p>Light bars and dashed lines show the range of values, heavy bars medians. Boxes give the inter-quartile values. Sample sizes are given in brackets. Values not sharing a common superscript are significantly different for P<.</p