King penguins rewarm their skin temperature to normothermia

during the night at sea: a descriptive study in condition of captivity

Agnès Lewden1,2, Tessa van Walsum3, Caroline Bost4, Thibaut Hestin4 and Yves Handrich1,2

Temperature (temp.) of 8 king penguins has been measured within peripheral(Sub-cutaneous flank) and internal tissues (Abdominal cavity, abdo) while the bird was either resting ashore, or resting in the water tank.

We treated the king penguins with 3 nutritional states :- Feeding (Feed), during which they were fed 4 meals during the day, and kept in the seawater tank.- Fasting (Fast), during which we placed them in the sea water tank on day 0, day 7, day10 or/and day 12 of fasting.-Refeeding (Refeed), during which we fed them 4 meals a day after they’ve undergonefasting.

We recorded activity (VEDBA) with accelerometers placed on the penguin’s back.

Agnes.lewden@iphc.cnrs.fr1,2 Université de Strasbourg , IPHC-DEPE, Strasbourg, France 2 CNRS, UMR 7178, Strasbourg, France

3 University of Roehampton, department of Life Sciences, london, UK 4 CEBC - Centre d’Etudes Biologiques de Chizé, CNRS, France

Nighttime body temperature variation of the penguin without human disturbance (for 12 hours) has been studied as similar to measured body

temperature of free living penguins

Context Methods

ResultsA

A

King penguin (Aptenodytes patagonicus) decrease tissue temperature(internal and peripheral) during their daily diving activity to minimiseoxygen consumption and thus extend dive. However, during nightly restin cold water (4°C), we observe body temperature rewarming (back tonormothermia).

Paradox : The king penguin has a higher energy expenditure duringnightly rest at sea than during their daily high intensity diving activity

Why do king penguins undergo nightly normothermia ?

Hypothesis : The individual needs to reconnect its blood circulation to peripheral tissues in order to store free fatty acids (FFA) into its subcutaneous adipose tissues

Prediction : After we have fed them, we should observe a nocturnal increase inperipheral tissue temperature. This increase in temperature should be absent inthe fasting condition, because the penguin will be in an energy saving modus.

Ashore Feed Fast (0) Fast (10) Refeed40

Internal and peripheral tissues are warmer in fasting than feeding state.Prolonged fasting has further increased body temp. compared to recent fasting

penguins

Average nightly body temp. in sea water is lower than ashore. However, during more than 50% of the night, their temp. in sea water is similar to their temp.

ashore (> 35°C)

Penguin activity decreases with increasing time in sea water tank. During fasting, body temp. increases with sea water duration

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

33

33.5

34

34.5

35

35.5

36

36.5

Fast (7) - 1er and 2nd night Fast (12) - 4th and 5th night

Act

ivit

y (

VE

DB

A)

Bo

dy

te

mp

. (°

C)

Flank

Abdo

Discussion

We found peripheral normothermia during the night in the sea water tank for both fasting and feeding. We suggest that individual needs to reconnect its blood circulation in order to store FFA during feeding AND to use FFA during fastingin sea water.

Peripheral temperature increases for both feeding and fasting state with

increasing time spent in the sea water tank. This phenomena could be explained

by body condition (fat or lean) and/or with a sea water tank activity that decreases with habituation.

AB

B

B

A

Penguins maintain the same peripheral temperature in a sea water tank as they do ashore.

Vasoconstriction/vasodilatation of blood flow, which involves the FFA mobilization, might explain their complex body temperature variation

Be continued : What is the cost to normothermia in sea water ?

Activity

Ashore Feed Fast (0) Fast (10) Refeed

25

30

35

40

Bo

dy

te

mp

. (°

C)

Take home message

Daytime

Nighttime

Abdominal temp. is higher than flank except in refeeding phase.The difference between both tissues decreases with increasing fasting

duration

A ABAB

BC

A

B

A A B