Seasonal pulses of migratory prey and annual variation in small mammal abundance affect abundance and reproduction by arctic foxes

Polar Biology

Supplementary material: number of foxes encountered, number of breeding dens, litter size, and small mammals captures

Gustaf Samelius • Ray T. Alisauskas • Serge Larivière

Gustaf Samelius

Grimsö Wildlife Research Station, Swedish University of Agricultural Sciences, Riddarhyttan, Sweden

Tel: +46 581 697334

Email:

Ray T. Alisauskas

Prairie and Northern Wildlife Research Centre, Environment Canada, Saskatoon, Canada

Serge Larivière

Cree Hunters and Trappers Income Security Board, Sainte-Foy, Canada

Table S1 Influence of various indices of small mammal abundance on local arctic fox abundance, breeding density, and litter size at Karrak Lake in 2000-2004. Included in the table are differences in AICC values between each model and the best fitting model (Di), number of model parameters (K) – including the intercept and s2, and model weights (wi). We used variation around the grand mean as our null model (called ‘no effect’ in the table). Small mammals include both lemmings and voles.

Model / K / Di / wi
Fox Abundance
Goose Nesting + Lemming Prev. Year + Goose Nesting ´ Lemming Prev.
Goose Nesting + Lemming + Goose Nesting ´ Lemming
Goose Nesting + Small Mammals + Goose Nesting ´ Small Mammals
Goose Nesting + Vole Prev. Year + Goose Nesting ´ Vole Prev. Year
Goose Nesting + Sm. Mam. Prev. Yr. + Goose Nesting ´ Sm. Mam. Prev. Yr.
Goose Nesting + Vole + Goose Nesting ´ Vole
No Effect
Breeding density
Goose Nesting + Lemming + Goose Nesting ´ Lemming
Goose Nesting + Vole + Goose Nesting ´ Vole
Goose Nesting + Small Mammals + Goose Nesting ´ Small Mammals
No Effect
Litter Size
Goose Nesting + Lemming + Goose Nesting ´ Lemming
Goose Nesting + Vole + Goose Nesting ´ Vole
Goose Nesting + Small Mammals + Goose Nesting ´ Small Mammals
No Effect / 5
5
5
5
5
5
2
5
5
5
2
5
5
5
2 / 0
1.3
3.9
4.4
5.2
5.6
10
0
1.6
3.0
9.8
0
1.1
2.9
9.2 / 0.52
0.27
0.07
0.06
0.04
0.03
<0.01
0.60
0.27
0.13
<0.01
0.55
0.32
0.13
<0.01


Table S2 Number of arctic foxes encountered and number of breeding dens per study area inside and outside the goose colony at Karrak Lake, Nunavut, Canada, in 2000 to 2004.

Year / Study area / Number of foxes seen* / Number of foxes seen corrected for distance travelled* / Number of breeding dens / Number of breeding dens corrected for terrestrial habitat
2000
2000
2000
2000
2001
2001
2001
2001
2002
2002
2002
2002
2003
2003
2003
2003
2004
2004
2004
2004 / Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E / 2
1
0
1
3
5
1
0
2
3
1
0
1
2
4
0
0
1
.
1 / 1.89
1.08
0
0.99
2.84
5.42
0.98
0
1.89
3.25
0.98
0
0.95
2.17
3.91
0
0
1.08
.
0.99 / 2
2
0
2
1
1
0
1
0
0
0
0
1
1
0
1
2
1
0
1 / 2.96
3.94
0
2.32
1.48
1.97
0
1.16
0
0
0
0
1.48
1.97
0
1.16
2.96
1.97
0
1.16

* data on fox abundance from 2000 were not included in our analyses on variation in fox abundance because we did not have data on small mammal abundance from previous year for the first year of the study

Table S3 Litter size of arctic foxes inside and outside the goose colony at Karrak Lake, Nunavut, Canada, in 2000 to 2004.

Year / Study area / Den / Breeding pair / Litter size
2000
2000
2000
2000
2000
2000
2001
2001
2001
2003
2003
2004
2004 / Colony N
Colony N
Colony S
Colony S
Outside E
Outside E
Colony N
Colony S
Outside E
Colony S
Outside E
Colony N
Colony S / Action den
North Adventure den
Camp den
Slaughter den
Little Simpson den
Simpson den
Action den
Camp den
Simpson den
Camp den
Simpson den
North Adventure den
Camp den / Unknown + Brown Sugar
Blackie + unknown
BigShooter + unknown
Unknown* + Elvira
Unknown + unknown
Unknown + unknown
Unknown + Brown Sugar
Mick + Dolly
Simpson + unknown
Mick + Raven
Simpson + Delila
Ruben + Tologak
Mick + Raven / 10
11
9
4
7
10
7
7
8
5
7
7
4

* no male observed at den despite >31 hours of observations from 25 June to 29 July


Table S4 Number of small mammals captured per study area inside and outside the goose colony at Karrak Lake, Nunavut, Canada, in 2000 to 2004.

Year / Study area / Number of collared lemmings captured / Number of brown lemmings captured / Number of red-backed voles captured / Number of trap-nights
2000
2000
2000
2000
2001
2001
2001
2001
2002
2002
2002
2002
2003
2003
2003
2003
2004
2004
2004
2004 / Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E
Colony N
Colony S
Outside W
Outside E / 2
4
4
0
0
0
2
0
0
0
0
0
1
0
0
2
0
0
.
0 / 0
0
0
1
0
0
0
2
0
0
0
0
0
0
0
0
0
0
.
0 / 0
0
3
0
5
0
1
1
2
0
6
2
0
0
1
0
1
0
.
1 / 147
142
118.5
143.5
147
145.5
143
144
148.5
146.5
149
142.5
145
149
146.5
148
146.5
144
.
147.5