Phase-dependent red fox expansion into the tundra: Implications for management

Expansion of boreal species into tundra ecosystems is a consequence of climate change and human exploitation that threatens local species through increased predation, competition, and pathogen transmission. Under these circumstances, efficient control of expanding boreal species may be necessary, but the efficiency of such action depends on understanding the ecological influences of expansion. The red fox (Vulpes vulpes) is expanding into the tundra across the Arctic. In Scandinavia, red foxes threaten local tundra species and communities including the endangered Arctic fox (V. lagopus). The ecological dynamics in the tundra are influenced by small rodent cycles (classified into different phases based on seasonal abundance fluctuations), which can affect red fox expansion, distribution, and abundance. We used a 17-year (2004–2020) dataset from the tundra in Sweden, consisting of raw snow track data, to test how cyclic prey influenced red fox distribution and abundance, and subsequently ..., Rodent and red fox monitoring and control
Västerbotten County has monitored abundance of predators yearly through snow track surveys since 2004 (Stoessel et al. 2019); we used data from 2004–2020. This monitoring follows the wildlife triangle scheme (Lindén et al. 1996). Within the study area, there are 28 randomly distributed triangular transects, which are 12 km in length (i.e., 4 km on each side of the triangle), permanent, and are distributed across the nature reserve (total area of nature reserve is 565 000 hectare) (Stoessel et al. 2019). Only 2 out of 28 triangles were located below the treeline. Fieldworkers on snowmobiles conducted monitoring in March-April, only on days after new snowfall or wind to ensure detection of recent tracks (Linden et al. 1996). For each snow track present, trained fieldworkers recorded a global positioning system point and identified the focal species based on the overall shape and pace of the tracks (Stoessel et al. 2019). Snow tracking can mainly d..., , # Data from: Phase-dependent red fox expansion into the tundra: Implications for management

Data consists of seven columns: **Year; Small rodent phase; Triangle identity; Number of red fox tracks; Number of red fox tracks/km; Number of small rodent tracks; Number of small rodent tracks/km**

**Categorical values included in column B (Phase of small rodent cycle):**

**Increase** = Small rodent abundance is higher than the low phase but lower than the peak phase

**Peak** = The highest small rodent abundance over the cycle, appearing after the increase phase and before the low phase

**Low** = A distinct decline in small rodent abundance relative to the other phases

**Post-peak** = Small rodent densities had declined but remained relatively high