Brage NP

Pavlova, Olga

Winther, Jan-Gunnar

English

Sea ice concentration off Dronning Maud Land, Antarctica

Ohta, Yoshihide

Larionov, Alexander N.

Tebenkov, Alexander M.

Lepvrier, Claude

Maluski, Henri

Lange, Michael

Hellebrandt, Barbara

Single-zirkon Pb-evaporation and 40Ar/39 dating of the metamorphic and granitic rocks in north-west Spitsbergen

Burkow, Ivan C.

Herzke, Dorte

Wolkers, Hans

Gabrielsen, Geir Wing

Norwegian

Analyse av bromerte flammehemmere, PCB og pesticider inkludert toksafen i polarmåke (Larus hyperboreus) fra Bjørnøya

Casacchia, Ruggero

Lauta, Francesca

Salvatori, Rosamaria

Cagnati, Anselmo

Valt, Mauro

Ørbæk, Jon Børre

Radiometric investigation of different snow covers in Svalbard

Criscuolo, Francois

Gauthier-Clerc, Michel

Le Maho, Yvon

115Criscuolo et al. 2001: Polar Research 20(1), 115–118
Brood patch temperature during provocation of incubating 
common eiders in Ny-Ålesund, Svalbard
Francois Criscuolo, Michel Gauthier-Clerc, 
Yvon Le Maho & Geir W. Gabrielsen
In this short note we describe the behaviour and body temperature 
changes of three incubating female common eiders (Somateria mollis-
sima) during provocation made by humans approaching the nest. The 
study site was near the settlement of Ny-Ålesund, Svalbard. Temperature 
transmitters were implanted subcutaneously at the brood patch and data 
recorded using a VHF receiver. We found that the female eiders in the 
experiment exhibited a passive defence response (“freezing”), accompa-
nied by a significant drop in brood patch temperature (0.6 °C) during 
provocation; this temperature drop lasted for 5 minutes. These results 
accord with other studies of the physiological changes which accompany 
the passive defence response in birds and other animals.
F. Criscuolo, M. Gauthier-Clerc & Y. Le Maho, Centre d‘Ecologie et Physiologie Energetiques, CNRS, 23 
rue Becquerel, 67087 Strasbourg Cedex 2; G. W. Gabrielsen, Norwegian Polar Institute, Polar Environmen-
tal Centre, N-9296 Tromsø, Norway.
Environmental stressors, such as approaching 
predators, induce physiological changes in birds, 
mammals and other animals. Autonomic 
responses must enhance the physiological and 
behavioural ability of the animal to cope with 
these events (Harvey et al. 1984). In wild birds, 
two types of behavioural responses have been 
described: the active and the passive defence 
responses. The former involves the activation of 
the sympathetic nervous system, which induces 
the “fight-or-flight” response. The animal reacts 
actively against the stressor, preparing itself either 
to confront the threat or to escape (Gabrielsen 
& Smith 1995). The physiological changes which 
accompany the active defence response include 
increased heart rate and respiration, redistribu-
tion of the blood flow to the skeletal muscles, 
enhanced glycemia and higher body temperature 
(Siegel 1980; Culik et al. 1990; Gabrielsen & 
Smith 1995). In contrast, other birds show a 
passive defence response in which the animal 
crouches or freezes (Gabrielsen, Blix et al. 1985). 
This behaviour is particularly suited to incubat-
ing birds, which, by remaining motionless on the 
nest, enhance their chances of being undetected 
by predators (Gabrielsen 1984; Steen et al. 1988). 
The physiological aspects of the passive defence 
response include reduced skeletal blood flow and 
lowered heart rate and respiration (which lessens 
the body odour emitted, hindering detection by a 
predator) (Gabrielsen & Smith 1995).
In a previous study of incubating female com-
mon eiders (Somateria mollissima) in Svalbard, 
Gabrielsen (1984) found that both females nest-
ing close to the settlement of Ny-Ålesund and 
those nesting in dense colonies on small islands in 
the area showed the passive (“freezing”) defence 
response. However, the physiological changes 
accompanying this behavioural response showed 
some interesting differences  between the birds 
nesting in the settlement vs. the island colonies 
(see discussion in Gabrielsen 1984).
Research Note
116 Brood patch temperature during provocation of incubating common eiders 
Although respiration and heart rate data have 
been recorded during provocation of incubating 
common eiders in Svalbard, less is known about 
the effect on body temperature of incubating 
eiders. In this paper we describe the changes in 
body temperature, measured at the brood patch, 
during human provocation of incubating female 
eiders breeding in Svalbard. In this species, main-
taining a constant nest temperature is of espe-
cially important because the high Arctic is a 
harsh environment in which eggs can cool rap-
idly, and frequent reheating of eggs is energet-
ically demanding for a bird fasting during the 
24 - 26 day incubation (Korschgen 1977; Gabriel-
sen, Mehlum et al. 1991). After arriving at the 
Svalbard breeding site in mid-April, the female 
lays a clutch of 4 - 6 eggs, which it then incu-
bates alone. During this period, the female relies 
entirely on its body reserves for its energy needs, 
losing 30 - 40 % of its initial body mass (Kor-
schgen 1977; Parker & Holm 1990; Gabrielsen, 
Mehlum et al. 1991; Criscuolo et al. unpubl. data). 
This fasting strategy enables the female eider to 
maintain a high level of nest attendance (Melhum 
1991; Criscuolo et al. unpubl. data), which reduces 
egg predation—mainly from gulls (Larus hyper-
boreus).
Materials and methods
The fieldwork was carried out in Ny-Ålesund 
(78°55 N), on the western coast of Spitsbergen. 
In June 1999, three female eiders nesting close to 
the settlement were caught on the nest and trans-
ported to the Norwegian Polar Institute labora-
tory (less than 150 m away). During the females’ 
absence from the nest, the eggs were covered 
with down and grass to avoid nest predation and 
egg cooling (egg temperatures were not meas-
ured during the study). The eiders were anaesthe-
tized with isofluorane-enriched O2. Temperature 
transmitters (TXH 2 radio tag 148 MHz, Televilt 
International) were implanted subcutaneously in 
the brood patch, the defeathered abdominal area 
which functions to warm eggs. The birds were 
transported back to the nest, still under anaes-
thesia, 100 - 120 min after being captured. The 
birds were placed on the nest and awoke from the 
anaesthesia while sitting on the eggs.
Behavioural observations of the incubating 
eiders were done from behind a hide, ca. 50 m 
away from the nest. Body temperature was 
recorded (± 0.1 °C) every 5 - 10 sec by a VHF 
receiver placed 100 m away from the nest site. 
After implantation we did not observe nest deser-
tion. However, one female eider lost her eggs two 
days after implantation. The two other females 
incubated until hatching. Only one female was 
recaptured at the end of the experiment and its 
thermistor retrieved under anesthesia.
The defence response was provoked by the 
approach of a human, walking slowly toward the 
female on the nest. The person stayed two m away 
from the bird for 7 min (including the approach 
period) and then left the area. The birds were 
never flushed from their nests. The provocation 
experiment was carried out twice a day—morn-
ing and evening. Each bird was provoked by 
humans seven times (n = 7).
Brood patch temperature was measured: 1) 
before the experiment, as the mean brood patch 
temperature during the two minutes before human 
provocation; 2) during provocation, as the mean 
brood patch temperature during the 7 min of 
human presence; and 3) after the provocation, as 
the mean brood patch temperature recorded for 
an additional 5 min following the researcher’s 
withdrawal from the breeding area. This study 
was approved by the Norwegian Animal Research 
Authority, the ethical committee of the Institut 
Français pour la Recherche et la Technologie 
Polaires, the Norwegian Polar Institute and the 
Governor of Svalbard.
 
Fig. 1. Effect of the approach of a human towards the nest on 
body temperature of incubating female eiders. After 7 min of 
provocation the stress experiment stopped (T7) and the tem-
perature of the bird was recorded for an additional 5 min (T7 
to T12). This experiment was repeated 7 times on three female 
eiders. Body temperature at T7 was significatively different 
from the initial and final body temperatures.
117Criscuolo et al. 2001: Polar Research 20(1), 115–118
Statistical analysis was carried using an 
ANOVA for repeated measurements, followed 
by post-ANOVA Tukey tests. Values are means ± s.e.
Results
Upon provocation there was an immediate cessa-
tion of all outwardly discernible body movement. 
In a characteristic freezing posture, the head was 
held against the body and eyes were open. The 
birds remained motionless on the nest during the 
entire 7 min provocation.
The mean brood patch temperature during 
normal (undisturbed) incubation for the three 
birds was 39.7 ± 0.1 °C (n = 7), 41.0 ± 0.2 °C 
(n = 7) and 39.2 ± 0.1 °C (n = 7). Average values 
for all three birds before the experiment was 
40.0 ± 0.2 °C (range 39.2 - 42.0 °C, n = 21). During 
the provocation experiment, the brood patch tem-
perature of each incubating female changed sig-
nificantly (ANOVA, F = 13.87, p < 0.0001; Fig. 
1). After 7 min of human provocation, the brood 
patch temperature decreased to 39.4 ± 0.2 °C 
(range 38.5 - 41.4 °C, Tukey test, n = 21, T = -4.99, 
p < 0.0001). Five min after the end of the stress 
experiment, the birds recovered a brood patch 
temperature of 39.9 ± 0.2 °C, comparable to the 
initial value (range 39.1 - 41.7 °C, Tukey test, 
n = 21, T = -1.038, p = 0.55). An example of the 
temperature changes is illustrated in Fig. 2.
Discussion
As found in a previous study (Gabrielsen 1984), 
incubating female eiders nesting close to a human 
settlement show the passive defence response 
(freezing) when provoked by humans. The drop 
in eider brood patch temperature observed in this 
study is probably related to the activation of the 
parasympathetic nervous system and a reduction 
in blood flow to the skeletal muscles (Gabrielsen 
& Smith 1995). The passive behavioural response 
is also found in willow ptarmigan (Lagopus lago-
pus) in Norway (Steen et al. 1988) and in Svalbard 
ptarmigan (Lagopus mutus hyperboreus) (Gabri-
elsen, Blix et al. 1985). Ground-nesting birds typ-
ically crouch to the ground and freeze, relying 
on their cryptic colouration and reduced respira-
tion to remain undetected. In opossum (Didelphis 
marsupialis) and deer mice (Peromysus manicu-
latus), the passive defense response is accompa-
nied by a drop in body temperature: a 0.6 °C drop 
in body temperature among opossum (Gabrielsen 
& Smith 1985) and a several degree drop in deer 
mice (Rosenmann & Morrison 1974).
Brood patch temperature measurements 
obtained in this study are well within the values 
obtained by Rahn et al. (1983) and Gabrielsen, 
Mehlum et al. (1991) from female eiders. Gabriel-
sen, Mehlum et al. measured a body temperature 
of 40.1 °C in non-incubating females. Rahn et 
al. measured the body temperature in the proven-
triculus part of the intestine after capture on the 
nest (39.1 ± 0.4 °C), as well as the external brood 
patch temperature with a thermistor implanted in 
an artificial egg (38.5 ± 0.6 °C).
It is interesting to compare the active defence 
response of penguins with the passive defence 
response of incubating eiders. When provoked, 
incubating Adélie (Pygoscelis adeliae) and gentoo 
penguins (P. papua) and moulting emperor pen-
guins (Aptenodytes forsteri) show increased heart 
rate (Culik et al. 1990; Nimon, Schroter & Stone-
house 1995; Nimon, Schroter & Oxenham 1996) 
and a rise of 0.8 °C in stomach temperature (Regel 
& Pütz 1997). For these large, conspicuous birds, 
freezing is not an appropriate strategy against 
predators. In contrast, motionless, cryptically col-
oured eiders can be undectectable to predators, 
even from a few meters (pers. obs.). Moreover, 
penguins are better able to defend their nests 
against predators (Handrich, pers. comm.) than 
are female eiders, e.g. against Arctic fox (Alopex 
lagopus) (Ferens 1962): staying motionless is the 
Fig.2. Typical profile of brood patch temperature in an incu-
bating female eider during provocation. The duration of the 
presence of a human close to the nest is indicated by the black 
line.
118 Brood patch temperature during provocation of incubating common eiders 
more appropriate response for eiders.
Staying on the nest is also the most adaptive 
response in the context of the harsh environment 
of Svalbard. The ambient temperature in the study 
area during the incubation period (4 - 6 °C) is 
well below the optimal incubation temperature 
for the eggs (35 - 40 °C; Webb 1987); eggs cool 
markedly in the absence of an incubating parent. 
In greater snow geese (Anser caerulescens atlan-
tica), birds nesting in the high Arctic and which 
only leave the nest for 25 min (2 - 8 recesses per 
day), the egg temperature decreased by 2.8 °C on 
average (Poussart et al. 2000). Similarly, a drop 
of 4.2 °C was recorded in spectacled eider (Soma-
teria fisheri) for a recess duration of 37 min (Flint 
& Grand 1999). Incubating common eiders do not 
take recesses exceeding 10 - 15 min and always 
cover their eggs with down before leaving the 
nest, thus minimizing their cooling rate (Mehlum 
1991; Criscuolo et al. unpubl. data).
With a mean value of 39.6 °C, common eiders 
show one of the highest brood patch temperatures 
of incubating birds (Drent 1975). The brood patch 
temperature drop which this study has shown to 
occur during provocation by a “predator” could 
have negative effects for eider eggs, but cooling 
is much more precipitous if the female actually 
leaves the nest, especially if it is unable to cover 
its eggs with down first. Moreover, reheating of 
the clutch after temporary nest desertion also has 
an energetic cost, even more deleterious for a 
bird which fasts for the duration of the incubation 
period.
Acknowledgements.—The financial support for the present 
work was provided by the Institut Français pour la Recherche 
et la Technologie Polaires, the Norwegian Polar Institute and 
the European Community (funding to Ny-Ålesund as a Large 
Scale Facility ). The authors want to thank Halvar Lundvig-
sen and Moskal Wojtek for their help and kindness during the 
work in Ny-Ålesund.
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