Surviving
Surviving the
the arctic
arctic winter:
winter:
insights
insights into
into the
the foraging
foraging tactics
tactics
of
of aa terrestrial
terrestrial predator
predator
Arnaud Tarroux, Dominique Berteaux & Joël Bêty
Département de biologie,
Université du Québec à Rimouski
Canada Research Chair in
Conservation of Northern Ecosystems
Context
Context
Characteristics of the (arctic) winter
1. Harsh weather, extreme T°C, darkness, etc.
2. Food scarcity for most species
 food is among the most limiting factors
Context
Context
Species adapted differently to find/save energy
1.Migration
Context
Context
Species adapted differently to find/save energy
1.Migration
2.Hibernation
Picture from: www.firstpeople.us
Context
Context
Species adapted differently to find/save energy
1.Migration
Opt
ima
l for
theo aging
ry
2.Hibernation
3.Develop tactics to
find sparse resources
Context
Context
Species adapted differently to find/save energy
1.Migration
Opt
ima
l for
theo aging
ry
2.Hibernation
3.Develop tactics to
find sparse resources
 Sea ice allows for virtually unlimited movements
 If resources are scarce, foraging means more traveling
Study
Study objectives
objectives
1) Do arctic foxes optimize foraging on sea ice?
2) Factors influencing winter foraging movements?
Study
Study objectives
objectives
1) Do arctic foxes optimize foraging on sea ice?
2) Factors influencing winter foraging movements?
Methods
Methods
Indirect: study of movements (satellite tracking)
Compare movements to theoretical models
Optimal mouvements with:
abundant resources
sparse resources
Lé
vy
wa
lks
Bylot Island (73°N, 80 °W)
Sirmilik National Park
Methods
Methods –– fieldwork
fieldwork
From May to August
Fox captures (tomahawk cages or padded foot traps)
Breeding adults are outfitted with Argos collars
18 individuals satellite-tracked between 2007-2009
Track of a female arctic fox from July 2008 to July 2009
showing movement capacity
Most foxes stay relatively close to their denning area
Tracks (16 foxes) from July 2007 to July 2009
Results
Results –– modeling
modeling movements
movements
9 foxes followed Lévy
walks patterns
7 foxes had movements
unadapted to random
search of sparse resources
Study
Study objectives
objectives
1)Do arctic foxes optimize foraging on sea ice?
Those who travel further away seem to follow predictions of the
optimal foraging theory
But other individuals had different foraging tactics
Study
Study objectives
objectives
1)Do arctic foxes optimize foraging on sea ice?
Those who travel further away seem to follow predictions of the
optimal foraging theory
But other individuals had different foraging tactics
2) Factors influencing winter foraging movements?
(foraging distance from summer home range)
Which factors influence foraging trip characteristics ?
FACTORS
RESPONSE
- Season
- Sex
- Body Condition
- Food abundance: previous
summer
- Food abundance: winter
?
Distance from
Home Range
Factors
Factors related
related to
to food
food abundance
abundance
in
in space…
space…
…and
…and time
time
Fox summer
home ranges
Lemming abundance cycles
Snow Goose
Colony
Ims et Fuglei 2005)
Model results
Season
Body
Condition
Distance from
Home Range
Distance to
goose colony
Lemming
abundance
Conclusions
Conclusions
1) Capacity to store food in summer AND food
availability in winter (lemmings) influence fox
foraging movements
2) When both stored food and lemming abundance
levels are low, foxes must move further
 In this case, they optimize their search behaviour by
adopting “Lévy walks” movements
Exotic
Exoticcompetitors
competitorsof
ofarctic
arcticfoxes
foxes
Red
Redfox
foxfamily,
family,Bylot
BylotIsland
Island2008
2008
## 161
161
In the field:
A. Bourbeau-Lemieux
M.-C. Cadieux
C. Cameron
S. Descamps
A. Desjardins
D. Duchesne
D. Gallant
G. Gauthier
B. Kilukishak
B. Laliberté
M. Morissette
E. Muktar
F. Racine
E. Tremblay
Parcs Canada Pond Inlet
Bylot teams since 2006
!
u
o
y
k
n
a
Th
With analyses, ideas &
discussions:
M. Basille
A. Caron
P. Fauchald
Canada Research Chair in
Conservation
of Northern Ecosystems