Seasonal Influxes of Migratory Prey and Annual Variation in Small Mammal Abundance Affect

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: [email protected]

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 (i), number of model parameters (K) – including the intercept and 2, 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 i wi Fox Abundance Goose Nesting + Lemming Prev. Year + Goose Nesting  Lemming Prev. 5 0 0.52 Goose Nesting + Lemming + Goose Nesting  Lemming 5 1.3 0.27 Goose Nesting + Small Mammals + Goose Nesting  Small Mammals 5 3.9 0.07 Goose Nesting + Vole Prev. Year + Goose Nesting  Vole Prev. Year 5 4.4 0.06 Goose Nesting + Sm. Mam. Prev. Yr. + Goose Nesting  Sm. Mam. Prev. Yr. 5 5.2 0.04 Goose Nesting + Vole + Goose Nesting  Vole 5 5.6 0.03 No Effect 2 10 <0.01

Breeding density Goose Nesting + Lemming + Goose Nesting  Lemming 5 0 0.60 5 1.6 0.27 Goose Nesting + Vole + Goose Nesting  Vole 5 3.0 0.13 Goose Nesting + Small Mammals + Goose Nesting  Small Mammals 2 9.8 <0.01 No Effect

Litter Size Goose Nesting + Lemming + Goose Nesting  Lemming 5 0 0.55 Goose Nesting + Vole + Goose Nesting  Vole 5 1.1 0.32 Goose Nesting + Small Mammals + Goose Nesting  Small Mammals 5 2.9 0.13 No Effect 2 9.2 <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.

Number of foxes seen Number of breeding Number of corrected for distance Number of dens corrected for Year Study area foxes seen* travelled* breeding dens terrestrial habitat 2000 Colony N 2 1.89 2 2.96 2000 Colony S 1 1.08 2 3.94 2000 Outside W 0 0 0 0 2000 Outside E 1 0.99 2 2.32 2001 Colony N 3 2.84 1 1.48 2001 Colony S 5 5.42 1 1.97 2001 Outside W 1 0.98 0 0 2001 Outside E 0 0 1 1.16 2002 Colony N 2 1.89 0 0 2002 Colony S 3 3.25 0 0 2002 Outside W 1 0.98 0 0 2002 Outside E 0 0 0 0 2003 Colony N 1 0.95 1 1.48 2003 Colony S 2 2.17 1 1.97 2003 Outside W 4 3.91 0 0 2003 Outside E 0 0 1 1.16 2004 Colony N 0 0 2 2.96 2004 Colony S 1 1.08 1 1.97 2004 Outside W . . 0 0 2004 Outside E 1 0.99 1 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 Colony N Action den Unknown + Brown Sugar 10 2000 Colony N North Adventure den Blackie + unknown 11 2000 Colony S Camp den BigShooter + unknown 9 2000 Colony S Slaughter den Unknown* + Elvira 4 2000 Outside E Little Simpson den Unknown + unknown 7 2000 Outside E Simpson den Unknown + unknown 10 2001 Colony N Action den Unknown + Brown Sugar 7 2001 Colony S Camp den Mick + Dolly 7 2001 Outside E Simpson den Simpson + unknown 8 2003 Colony S Camp den Mick + Raven 5 2003 Outside E Simpson den Simpson + Delila 7 2004 Colony N North Adventure den Ruben + Tologak 7 2004 Colony S Camp den Mick + Raven 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.

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