During this period, wolf and moose abundances, moose kills and the wolf's social organization in packs have been estimated annually (during January and February) by aerial survey (see
Vucetich et al. (2002) for details).
These data permit us to analyse the system on three levels/scales that emphasize different aspects of the spatial and social organization of moose and wolves:
- 1
Per pack scale. Kills per wolf per day (calculated in each pack) studied in relation to pack size and moose abundance per pack territory (85 values of the kill rate, wolf abundance and moose abundance).
- 2
Whole island scale. Kills per wolf per day (computed over the whole island) as a function of total wolf and moose populations (28 values of the kill rate, wolf abundance and moose abundance).
- 3
Mixed scale. Kills per wolf per day in each pack, but studied as a function of total wolf and moose populations (85 values of the kill rate, 28 values of wolf abundance and moose abundance).
The ‘per pack’ scale considers each pack with its territory and the moose therein as an independent unit, but it ignores interactions among packs and the overlapping of territories. The ‘whole island’ scale represents the aggregated population level that avoids any spatial or social details. The ‘mixed’ scale finally tries to combine both views to account for both the wolf's social structure and the free movement of moose on the island.