Determinants of co-occupancy
In both winter and autumn, co-occupancy for lynx and wolf was relatively high indicating that both species have similar habitat requirements. In winter there was a weak effect of forest cover on the co-occupancy of lynx and wolf; co-occupancy increased slightly with proportion of forest cover >0.75. Increased forest cover may result in an increase in prey availability, which would yield higher co-occupancy between lynx and wolf which share some prey items (primarily roe deer, red deer calves), and the main prey species for wolf, the wild boar (Sus scrofa ) (Sin et al., 2019) shares similar habitat with red and roe deer. In autumn, terrain ruggedness was a negative predictor of co-occupancy for lynx and wolf, such that predicted co-occupancy was ~0 for the highest values of terrain ruggedness. This relationship is driven by the negative relationship between marginal occupancy for wolf and terrain ruggedness, which is also related to prey availability (see above) (Figure 2C). Because marginal occupancy for wolf is ~0 at high terrain ruggedness, co-occupancy for lynx and wolf is low as well. Additionally, co-occupancy between wolf and wildcat decreased with terrain ruggedness in autumn (Fig 3F) due to the low marginal occupancy for wolf at high terrain ruggedness. In winter however, co-occupancy of wolf and wildcat was predicted by proportion of forest such that increasing forest cover resulted in lower co-occupancy (Fig 3C). In both seasons, the co-occupancy of lynx and wildcat increased with terrain ruggedness, but the relationship was stronger in winter (Fig 3A, D). This relationship also provides further evidence that the negative relationship observed for lynx and wolf co-occupancy and terrain ruggedness was driven by wolf marginal occupancy.