Caribou, Climate Change, Predators and Diet

1
Caribou, Climate Change, Predators and Diet
Primary predators wolves, bears, golden eagles
2
Predators of caribou and wild reindeer

• Other known or potential predators
• wolverine
• lynx
• black bear
• polar bear
• coyotes
• raven (calves only)

3
Circumpolar variation in predators

• Western Arctic Herd 9 known and potential
  predators
• Greenland no known predators

4
(No Transcript)
5
Why monitor predators?

• Rangifer body condition is one of the most
  important factor in determining health of the
  caribou population

6
Why monitor predators?

• Rangifer body condition is one of the most
  important factor in determining health of the
  caribou population
• Changes in vegetation (climate change or
  industrial development) will affect rangifer body
  condition, and may result in shifts in predation,
  especially if alternate prey becomes scarce or
  more abundant in response to vegetation change

7
Why monitor predators?

• Rangifer body condition is one of the most
  important factor in determining health of the
  caribou population
• Changes in vegetation (climate change or
  industrial development) will affect rangifer body
  condition, and may result in shifts in predation,
  especially if alternate prey becomes scarce or
  more abundant in response to vegetation change
• A herd characterized by poor body condition that
  experiences a shift to more predation will take
  much longer to recover

8
change in the number and distribution of
predators
Caribou available to hunters
change in the number and distribution of caribou
and other prey species
change in plant foods and lichen available
climate change, industrial development, etc.
9
Wolves, bears, golden eagles and other predators
have a mixed diet

• Wolves - moose, caribou, sheep, small mammals and
  occasionally, birds
• Bears - roots, plants, berries, mammals, fish,
  birds
• Golden eagles - small mammals, caribou calves,
  lambs, birds

10
Stable isotopes a record of diet

• Diet may change with season, or with change in
  the prey base over time
• Predators carry a record of what they have been
  eating - that record is in the form of stable
  isotopes
• Isotopes of C and N can be isolated from body
  tissues, bone and hair.

11
Stable isotopes in food web studies predictable
levels of enrichment per trophic step (Paul
Matheus slide)
10 8 6 4 2 0 -2
secondary consumers
?15N
primary consumers
primary producers
-28 -27 -26 -25 -24
-23 -22
?13C
12
dietary studies based on variation in plant
isotopes mixing models (Paul Matheus slide)
10 8 6 4 2 0 -2
?15N
-28 -27 -26 -25 -24
-23 -22 -21 -20 -19
-18
?13C
13
Getting the baseline what is needed?

• Document historic and current key predators of
  each herd, by season (local users, researchers)
• Develop isotopic signature reference collection
• Collect hair and body tissue samples for
  predators from trappers and hunters where
  feasible, over several years and seasons
• Collect hair and body tissue samples for other
  prey species
• Characterize predator diet based on stable
  isotope signatures
• In future, determine if there are shifts in the
  isotopic signatures of the predator

14
10
Petasites
SI values of some modern tundra plants (Paul
Matheus slide)
8
Polygonum
Eriophorum
6
Carex
4
Salix
other grasses
2
?15N
Festuca
Betula
0
Artemisia
-2
lichen
-4
-6
Vaccinium
-32 -30
-28
-26

-24
-22 -20
?13C
15
Caribou
16
10
8
enrichment is tissue-specific different
metabolic pathways result in fractionation of
istopes
6
herbivore
(1
E
consumer)
4
5
?15N
2
3
0
plants
(diet)
-2
Herbivores
-4
bone collagen
-30
-28
-26
-24
-22
-20
10
8
2-3
6
3
4
?15N
flesh
2
(diet)
(Paul Matheus slide)
0
Carnivores
-2
-4
-30
-28
-26
-24
-22
-20
?13C