Habitat Use, Food and the Importance of Poultry in the Diet of the Red Fox Vulpes vulpes in Extensive Farmland in Poland

1. What they did

Most studies of red fox food and habitat have been done in places heavily changed by people, such as towns and intensive farmland. The authors studied foxes in extensively farmed land in western Poland, part of which is protected for birds, and asked how important domestic poultry is to these foxes, and whether eating poultry reduces fox predation on wild birds.

• Dens. They searched the whole study area for fox dens, mainly in autumn and winter when dens are easier to find, and checked them again during the study. At each den they recorded the habitat (forest, scrub or open land such as fields, meadows and fallow land) and the direction the entrance faced.
• Scats. Between May 2006 and May 2008 they collected 632 fox scats across the area, noting where each was found and how far it was from the nearest farm building. In the laboratory they soaked and broke up the scats and identified prey from bones and teeth, and from fur and feathers under a microscope.
• Biomass. For 433 scats they weighed the remains of each food group and used correction factors for digestibility to estimate how much of each food the foxes had eaten.
• Prey remains. They also recorded remains of prey found in the field near dens.
• Poultry and farms. For 13 fox territories with more than 30 scats each, they compared the share of poultry in the diet with the distance to the nearest farm building.

2. What they found

Dens

• Of 82 dens, 48 (58.5%) were in cover: 40 in forest and 8 among bushes. 24 (29.3%) were in open areas and 10 (12.2%) were on slopes such as sandy river banks.
• Den entrances did not face random directions. They faced north and west more often than expected (the abstract says north, northeast and west). Entrance direction did not differ between dens in cover and in the open.

Diet

• Rodents were the main food, found in 74.1% of all scats, mostly voles, especially the common vole.
• Birds were found in 33.5% of scats. Large birds, mainly poultry and game birds, were the most common.
• Plants (37.0% of scats), beetles (21.7%), and soil and small stones (19.3%) were also frequent. Large mammals such as roe deer, hare and wild boar appeared in only 11.5% of scats.
• By estimated biomass, rodents made up 44.6% of what the foxes ate and birds 35.0%, most of which were poultry. Plants made up 14.5%, hares 3.1%, deer carcasses 2.1% and insects 0.7%.

Prey remains near dens

• The remains of 26 birds and 12 mammals were found near dens. Most of the birds were domestic: 9 hens and 9 hen eggs, and 4 domestic pigeons. Wild birds included pheasants, common buzzards, grey herons, a white stork, a hooded crow, a raven, a mallard and a greylag goose.
• The mammals were 7 roe deer, 3 brown hares, a feral cat and domestic cattle (presumably eaten as carrion).

Poultry and distance to farms

• The closer a fox territory was to farm buildings, the more poultry the foxes ate (r = 0.587, n = 13, p = 0.035).
• The share of poultry in the diet was not related to the share of wild birds.

3. What they concluded

• The diet was broadly similar to that found in other farmland studies in Central Europe, with voles as a key food.
• Poultry was an important and easily available food for foxes even in extensive farmland, and less so further from farms.
• Eating poultry did not reduce how much foxes preyed on wild birds in this protected area. Instead, the authors suggest poultry was eaten in place of hares and roe deer, which were quite rare in the area compared with other studies.
• Foxes in farmland adapt to conditions made by people. The authors suggest the foxes probably learned to use poultry as a major food, that this extra food probably helped fox numbers rise quickly, and that good food conditions led foxes to move from traditional den habitats into open fields and meadows. They also think lower hunting pressure in recent years may have played a part.
• Because entrance direction was the same in covered and open habitats, the authors think entrance direction is shaped by more than protection from wind, perhaps also by the view around the den and access to food.

4. How tracking was or was not used

The study relied on signs rather than tracks. The researchers searched the study area for fox dens and recorded their habitat and entrance direction, collected fox scats across the area, and recorded prey remains found near dens. In the laboratory, prey were identified from bones, teeth, fur and feathers in the scats. The paper does not say how scats were confirmed as fox scats or how prey remains near dens were linked to foxes. No footprints or trailing are reported.

5. Tracker or observer certification

Not reported. The paper does not say who found the dens, collected the scats or identified the prey remains, beyond thanking three people for help with field work and prey identification. The diet results depend on scats being correctly identified as fox scats.

6. Other technologies, skills or innovations

• Light microscope to identify fur and feather remains in scats.
• Digestibility correction factors to turn the weight of remains into the biomass eaten.
• Circular statistics (Oriana software) to test the direction of den entrances.

7. Implications for conservation (from the paper)

• To judge how much foxes affect prey in a protected area, managers need to know both fox numbers and where foxes live, and what they eat.
• Foxes may strongly affect wild animals, including high-priority protected species, in less disturbed areas such as this Natura 2000 site.
• Poultry kept near farms is easy food for foxes, and it did not take pressure off wild birds in this protected area.