Description of the data and file structure:

Data file: Red_fox_data.csv

Variables:

• Year: year from 1973-2024
• Fox_litter: number of red fox litters. Data on fox reproduction were obtained from annual monitoring of fox litters conducted at Grimsö Wildlife Research Area (135 km2) in south-central Sweden since 1973 (https://data.fieldsites.se/portal/). Surveys were carried out each May-June by inspecting all known dens (varying 120-210 among years). The presence of den entrance wear, pup scats or prey remains was used to confirm reproductive activity.
• Wolf_presence: absence (0, 1973 - 2003) or presence (1, 2004 - 2024). Wolves re-established with one territory completely covering Grimsö Wildlife Research Area in winter 2003-2004.
• Lynx_presence: absence (0, 1973 - 1995) or presence (1, 1996 - 2024). Lynx re-establishment in Grimsö Wildlife Research Area took place in winter 1995-1996 and the first lynx reproduction in the area was observed in spring 1996
• Lynx_only_presence: absence (0, 1973 – 1995 and 2004 - 2024) or presence (1, 1996 - 2003). The period with only lynx presence and no wolf presence.
• Sarcoptic_mange: absence (0) or presence (1). At Grimsö Wildlife Research Area (GWRA), sarcoptic mange was prevalent mainly between 1983 and 1989, a period associated with local fox population decline (Lindström et al. 1994, Ecology 75: 1042 – 1049). Sarcoptic mange did not disappear after 1989, but the prevalence was much lower.
• Vole_index_spring: number of vole individuals trapped per 100 trap nights. Vole density index estimates were based on biannual snap-trap surveys targeting bank voles and field voles conducted at GWRA since 1973 (https://data.fieldsites.se/portal/). One thousand traps distributed over 20 sampling sites covering 1 hectare each in 10 groups of 5 traps, were set out every year for three nights in spring and fall at GWRA since 1973. The vole density index was expressed as number of catches/100 trap nights, and the same sites were used each year.
• Hare.index: proportion of plots with hare droppings. The presence of droppings of hare (mountain hare and European hare) and woodland grouse (capercaillie, black grouse; and hazel grouse (Tetrastes bonasia)) were monitored in late April to mid-May in permanent 10 m2 plots which had been previously cleared in late autumn south-eastern quadrant). The plots (about 500 plots every year) were 10 × 1 m and spaced 100 m apart along north-south oriented transects. During 1997-2024 the monitoring covered the entire study area (https://data.fieldsites.se/portal/), with thirty-two squares (1 × 1 km) systematically distributed within the study area. Four circular 10 m2 plots (radius of 1.78 m) were monitored every 200 m along the perimeter of each square (resulting in about 2400 plots every year). For both periods (1977-1996 and 1997-2024), the density index was expressed as proportion of plots with hare and grouse droppings, respectively. We used a reduced data set (n = 48) when hare and grouse density indices were included in the models, as the hare and grouse monitoring started in 1977.
• Grouse.index: proportion of plots with grouse droppings The presence of droppings of hare (mountain hare and European hare) and woodland grouse (capercaillie, black grouse; and hazel grouse (Tetrastes bonasia)) were monitored in late April to mid-May in permanent 10 m2 plots which had been previously cleared in late autumn south-eastern quadrant). The plots (about 500 plots every year) were 10 × 1 m and spaced 100 m apart along north-south oriented transects. During 1997-2024 the monitoring covered the entire study area (https://data.fieldsites.se/portal/), with thirty-two squares (1 × 1 km) systematically distributed within the study area. Four circular 10 m2 plots (radius of 1.78 m) were monitored every 200 m along the perimeter of each square (resulting in about 2400 plots every year). For both periods (1977-1996 and 1997-2024), the density index was expressed as proportion of plots with hare and grouse droppings, respectively. We used a reduced data set (n = 48) when hare and grouse density indices were included in the models, as the hare and grouse monitoring started in 1977.

Data file: Hare_grouse_SO_vs_other.csv

Monitoring method (early 1977-1996 and late 1997-2024) is completely confounded with the presence of lynx (1996-2024) and partly with presence of both lynx and wolves (2004-2024). Therefore, we cannot add monitoring method as a random factor in the analyses. Instead, we tested if the hare density index and grouse density index in the south-eastern quadrant was correlated with the other quadrants (south-west, north-east and north-west quadrants) and they were not significantly different
During 1997-2024 the monitoring covered the entire study area (https://data.fieldsites.se/portal/), with thirty-two squares (1 × 1 km) systematically distributed within the study area. Four circular 10 m2 plots (radius of 1.78 m) were monitored every 200 m along the perimeter of each square (resulting in about 2400 plots every year). The density index was expressed as proportion of plots with hare and grouse droppings, respectively.

Variables:

• Year: year from 1997-2024
• n.plot: total number of plots
• SO.n.plot: number of plots in the south-eastern quadrant
• SO.hare.prop: proportion of plots with hare droppings in the south-eastern quadrant
• SO.grouse.prop: proportion of plots with grouse droppings in the south-eastern quadrant
• other.n.plot: number of plots in the other quadrants
• other.hare.prop: proportion of plots with hare droppings in the other quadrants
• other.grouse.prop: proportion of plots with grouse droppings in the other quadrants

Data files are tab-delimited with a comma decimal

Code:

R script: Red_fox.R

Analyzing factors influencing red fox numbers, hare density index and grouse density index, using the data file “Red_fox_data.csv”

R script: Hare_grouse_SO_vs_other.R

Relationship between hare and grouse density index in the SE quadrant and the other quadrants, using the data file Hare_grouse_SO_vs_other.csv