Red foxes (Vulpes vulpes) use rabbit (Oryctolagus cuniculus) scent marks as territorial marking sites

1. What they did

Many mammals mark their territories with scent, and faeces make especially good marks because they add something to see as well as smell. Red foxes and European rabbits both rely heavily on scent, and both leave their marks in clearings and at landmarks. Rabbits were the foxes’ main food in this area. The authors expected foxes to mark more, and to make their marks easier to find, where rabbits were more plentiful, as a way of defending their food.

From October 2005 to April 2006 they studied a suburban forest near Madrid, Spain:

• Plots. They chose 25 fixed plots of 50 × 50 m at random, spaced far enough apart that each held a separate rabbit population, and visited them every week.
• Rabbit density. In each plot they cleared all rabbit pellets from four 1 × 1 m squares and counted the new pellets a week later. A fifth square with a known number of fresh pellets let them correct for pellets lost to rain, sun and vegetation. They then split the plots into high density (12) and low density (13).
• Fox scats. For every new fox scat they recorded whether it lay on a road (any path, whatever its width) or in a clearing (including path intersections), and whether it lay directly on a rabbit latrine or pawscrape.
• What was available. They measured how much clearing and road each plot had, and in 16 plots the number and area of rabbit latrines and pawscrapes, so they could compare where foxes left scats with what they would expect by chance.

2. What they found

• They recorded 335 fox scats. Plots with more rabbits had significantly more fox scats.
• Foxes left more scats in clearings than on roads. This did not depend on rabbit density: scats in clearings, and scats on roads, were no more common in high density plots than in low density ones.
• Plots with more rabbits had more fox scats placed on rabbit latrines and pawscrapes.
• Foxes placed scats on rabbit marks far more often than expected by chance, for latrines and for pawscrapes alike.
• Foxes left more scats on pawscrapes than on latrines, but pawscrapes were also more common. Once availability was taken into account, foxes did not prefer one over the other.
• Within the 16 plots where rabbit marks were measured, how much foxes used latrines, or pawscrapes, did not depend on rabbit density.

3. What they concluded

• Foxes and rabbits were closely linked in space. More scats where rabbits were plentiful suggests foxes spent more time in these richer patches, adjusting their territories to their prey. They also marked these patches more, and not at random.
• Foxes chose clearings whatever the rabbit density. In this dense forest, clearings were almost the only breaks in the vegetation, and many small tracks lead into them, so a mark there is more likely to be found.
• Rabbit latrines and pawscrapes are already conspicuous signals that combine sight and smell. Adding a scat on top may make the fox’s mark even easier to detect. The authors suggest foxes use rabbit marks as “amplifiers” for their own, and that rabbit marks may also tell foxes where their prey is.
• They saw two patterns in fox marking: one shaped by the general layout of the habitat (clearings), and one shaped by how many rabbits there were. Overall, foxes appear to defend their food by marking more, and more visibly, where their prey is abundant.

4. How tracking was or was not used

The whole study rests on finding and identifying signs. Each week the team found and recorded new fox scats, and noted whether they lay on rabbit latrines or pawscrapes. Rabbit numbers were estimated from counts of rabbit pellets. No trailing was reported, and the paper does not say how fox scats were told apart from those of other animals.

5. Tracker or observer certification

Not reported. The paper does not say who searched the plots or identified the scats, latrines and pawscrapes, although every result depends on these identifications.