# Effect of felling on red fox (Vulpes vulpes) and pine marten (Martes martes) diets in transitional mixed forest in Belarus

> What happens to a fox’s dinner when the forest is clearcut? Analysing more than 3500 scats from two Belarusian forests, researchers found that heavy logging turned both red foxes and pine martens towards voles that thrive in the grassy clearcuts. The two predators, whose diets had been almost the same, began to go separate ways.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2010-sidorovich-sidorovich-effect-felling-red-fox/

## Citation and access

- **Authors:** Vadim E. Sidorovich, Anna A. Sidorovich and Dmitry A. Krasko
- **Year published:** 2010
- **Journal or source:** Mammalian Biology
- **Full citation:** Sidorovich, V. E., Sidorovich, A. A. and Krasko, D. A. 2010. Effect of felling on red fox (Vulpes vulpes) and pine marten (Martes martes) diets in transitional mixed forest in Belarus. Mammalian Biology 75(5): 399–411.
- **DOI:** 10.1016/j.mambio.2009.10.003
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1016/j.mambio.2009.10.003

## Tags

- **Species:** Mammals > Pine marten; Mammals > Red fox
- **Region:** Europe > Belarus
- **Tracking:** Scat; Tracking; Tracks and signs identification
- **Behaviour and ecology:** Behaviour; Feeding; Human disturbance; Predation; Scavenging
- **Data type:** Existing data; New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology
- **Year published:** 2010

## Detailed keywords

- **Species:** Studied: red fox (Vulpes vulpes) and pine marten (Martes martes). Food remains found in scats: Microtus voles, bank vole (Myodes glareolus), Apodemus mice, other small rodents, shrews, mole, eastern hedgehog (Erinaceus concolor), snow hare (Lepus timidus) and brown hare (Lepus europaeus), red squirrel, beaver, muskrat, mustelids, wild and domestic canids, young wild ungulates (including roe deer fawns), carcasses of older wild ungulates, livestock carrion, small birds, big and medium-sized birds, bird eggs, reptiles, amphibians, fish, beetles and other insects, fruits, seeds, herbs and honey. Mentioned as the cause of spruce die-off: engraver beetle (Ips typographus).
- **Location and habitat:** Two transitional mixed forests (between boreal conifer forest and more southern broadleaf forest) in Belarus. “Clay” area: Minsk and Smolevichi districts, Minsk region, central Belarus (about 53°N, 27°E); a densely forested area of 48 km² on rich clay soils, formerly about 60% mature spruce forest, with mixed conifer and deciduous forest, small meadows, and recent clearcuts that rose from under 10% to 15 to 50% after felling intensified in autumn 1998 (spruce die-off after beetle outbreak). “Sandy” area: Polotsk district, Vitebsk region, northern Belarus (about 55°N, 29°E); a forest tract of about 250 km² on poor sandy soils, dominated by pine with moss, lichens and dwarf berry shrubs, plus raised bogs; recent clearcuts and young forest rose from under 10% to about 20 to 30% after felling intensified in 2000. Clearcuts were usually 10 to 20 ha (range 1 to 100 ha). Snow cover usually 20 to 50 cm (up to 90 cm in places).
- **Topics:** diet analysis from scats, clearcut logging (felling), forest management, rodent prey, Microtus vole cycles, food niche breadth, diet overlap between two predators, niche divergence, seasonal diet change, carrion in winter, predation risk to pine martens from red foxes and birds of prey, snow conditions in clearcuts, soil productivity and prey supply. Inconsistencies in the paper: (1) Table 5 gives the periods as before 1995 to 1999 and after 2000 to 2005 for both areas, but for the clay area the methods and Tables 1 and 3 use 1995 to 1998 and 1999 to 2005. (2) The methods give 5952 prey items and other food items from red fox scats; the “food specimens” rows in Tables 1 and 2 add up to 5950. (3) For pine martens in the sandy area, the text says the diet became more diverse after heavy logging “in terms of %OC only”, but in Table 4 the cold-season niche breadth by biomass also rose (2.54 to 3.46). (4) The text gives diet overlap by biomass before heavy logging as 0.67 to 0.88, but Table 5 shows 0.50 to 0.88 (the clay area cold season is 0.50).
- **Statistics or models:** percentage of occurrence (%OC) and percentage of biomass consumed (, using digestibility coefficients from Jędrzejewska and Jędrzejewski 1998); Levins’ index of food niche breadth (28 food categories); simplified Morisita’s index of diet overlap (0 to 0.33 small, 0.34 to 0.66 middling, 0.67 to 1 large overlap); replicated goodness-of-fit test (G-statistic).
- **Data type:** New field data: 1904 red fox and 1624 pine marten scats collected 1995 to 2005, split into warm season (April to October) and cold season (November to March), before and after heavy logging. Existing data: pine marten diet in the clay area after heavy logging was taken from Shamovich (2004); vole population trends were taken from the authors’ other studies.

## Synopsis

### 1. What they did

Since the late 1990s, logging in Belarus has increased sharply, and clearcuts now cover a large part of many woodlands. Grass grows up in these clearcuts and rodents become more numerous there. Red foxes and pine martens are both common forest predators with flexible diets, so the authors asked how heavier felling changed what the two species eat, and whether it changed how much their diets overlap.

They worked in two forests in Belarus with very different soils:

- A “clay” area in central Belarus, with rich soils and many rodents. Heavy felling began in autumn 1998 after spruce trees died off following a bark beetle outbreak.

- A “sandy” area in northern Belarus, with poor pine forest and few rodents. Heavy felling began in 2000.

From 1995 to 2005 they collected 1904 red fox scats and 1624 pine marten scats, mostly along the animals’ tracks and near dens. They chose years that covered both peaks and lows of Microtus vole numbers, before and after heavy logging. In the laboratory they washed the scats and identified prey by hair under the microscope, and by feathers, bones, scales and insect remains. They calculated how often each food appeared and how much of the diet’s biomass it made up, separately for the warm and cold seasons. They then measured how broad each diet was and how much the two predators’ diets overlapped. For pine martens in the clay area after heavy logging, they used diet data from another study (Shamovich 2004).

### 2. What they found

Red foxes

- Before heavy logging, red foxes ate mostly mammals. Bank voles were their main rodent prey, and hares (and, in the clay area, hedgehogs) were also important. In the cold season they ate much more carrion, and in the sandy area they ate many fruits in the warm season.

- After heavy logging, in both areas and both seasons, red foxes ate far more Microtus voles (4 to 18 times more, depending on area, season and measure) and fewer bank voles. Microtus voles became their main rodent prey.

- Eating more voles meant eating less of other foods: carrion, hares and hedgehogs in the clay area; bank voles, fruits, birds, reptiles and carrion in the sandy area.

- Seasonal differences in the fox diet almost disappeared after heavy logging.

- In the rich clay area the fox diet became narrower; in the poor sandy area it became broader.

Pine martens

- Before heavy logging, pine martens in the clay area ate mostly mammals, especially bank voles, and many small birds. In the sandy area they relied on fruits, bank voles, beetles and birds in the warm season, and mostly on carrion of wild ungulates in the cold season.

- After heavy logging they ate more Microtus voles and more Apodemus mice, but kept eating bank voles at about the same level.

- In the clay area, birds and medium-sized mammals almost disappeared from the warm-season diet. In the sandy area, they ate fewer fruits.

- In the clay area the warm-season diet became narrower; in the sandy area it became more diverse (by frequency of occurrence).

Diet overlap

- Before heavy logging, the two predators’ diets overlapped strongly in both areas and seasons (Morisita’s index 0.83 to 0.89 by occurrence, 0.50 to 0.88 by biomass).

- After heavy logging, the overlap dropped (0.53 to 0.76 by occurrence, 0.40 to 0.51 by biomass). The main reason was that they took different rodents: foxes switched from bank voles to Microtus voles, while martens kept taking bank voles and added Apodemus mice.

### 3. What they concluded

- In both forests, heavier felling shifted red fox and pine marten diets towards rodents, especially Microtus voles. This matched the rise in vole and rodent numbers in clearcuts recorded in their earlier work.

- Red foxes may be drawn to clearcuts both by more rodents and by Microtus voles, which the authors describe as easier to catch than mice and bank voles.

- Pine martens may forage less in clearcuts because they are more exposed there to larger predators such as red foxes and birds of prey (in forest they can escape up trees), and because the deeper, harder-crusted snow in clearcuts makes it harder to catch rodents under the snow.

- The two predators’ diets, which had been very similar, drew apart once logging became heavy.

- The authors expect these changes to be short-term (perhaps 10 to 15 years): as clearcuts grow into young forest, rodents seem to decline sharply, and the predators’ diets would shift again. They also suggest that the response could be very different in broadleaf forests, where logging may reduce food for rodents.

### 4. How tracking was or was not used

Tracking was used to collect samples. The authors say most scats were collected “on tracks and nearby dens”, but they do not explain how scats were found or how they were assigned to red fox or pine marten. The dietary analysis itself was laboratory work on scat contents, identifying prey from hair, feathers, bones, scales and insect remains.

### 5. Tracker or observer certification

Not reported. The paper does not say who collected the scats or how scats of the two species were told apart. This matters because the whole study rests on red fox and pine marten scats being correctly identified in the field.

### 6. Other technologies, skills or innovations

- Microscopic identification of prey hair in washed scats, using published hair keys.

- Telling young ungulates (up to about two months old) from older ones by their hair: roe deer fawn hair in scats is shorter, more wiry and carroty-coloured, while older roe deer hair is longer, fragile and almost colourless. Hooves of young ungulates in scats also helped.

- Biomass estimates using digestibility coefficients, to correct for small prey being over-represented when only counting occurrences.

### 7. Implications for conservation (from the paper)

- Logging changes the prey available to forest predators and, through that, what they eat. Changes in predator diets could shift their predation pressure on prey populations and their interactions with other predators.

- Heavy clear cutting can create heavier predation risk for pine martens in open clearcuts and make winter foraging harder for them.

- The effects of felling on rodents and their predators may be short-lived as clearcuts regrow, and may differ in broadleaf forests.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- Scat-based diet studies like this one depend on the scats being correctly assigned to species. Red fox and pine marten scats can look alike, and the paper does not report how they were told apart or who collected them. Finding scats on an animal’s tracks, as the authors did for most samples, is one way trackers can link a scat to the animal that left it.

## Cite this summary

Lawrence, K. 2026. Summary of: Effect of felling on red fox (Vulpes vulpes) and pine marten (Martes martes) diets in transitional mixed forest in Belarus (Sidorovich and Sidorovich et al., 2010). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2010-sidorovich-sidorovich-effect-felling-red-fox/