Winter distribution of European pine marten (Martes martes) scats in a protected area of Galicia, Spain

1. What they did

In Spain, little is known about where European pine martens live and what habitat they choose, yet this is needed to manage and conserve them. The author asked which habitat features go with the presence of pine marten scats in winter.

The study ran from October 2001 to March 2002 in a 5,200 ha area of Montes do Invernadeiro Natural Park in Galicia, northwest Spain:

• Survey design. The area was divided into 52 cells of 100 ha each. A single observer walked 140 transects of 200 m, two or three times in each cell over the six months, covering every plant community. Transects were at least 1 km apart. Snow made some cells hard to reach, so the number of transects per cell varied.
• Scat identification. Pine marten scats were told apart from those of other medium-sized carnivores by their size, appearance and “pleasant scent”. Beech marten scats look very similar, but beech martens are not known in the area, which visual surveys and camera traps confirmed.
• Why winter. In summer pine martens eat mostly fleshy fruit, which may change how often they defecate. In winter they eat mainly small mammals, so winter surveys reduce this effect.
• Analysis. For each cell, an abundance index (scats per kilometre surveyed) was compared with forest and brushwood cover (from maps) and with rocky areas, watercourses, altitude, orientation and slope (recorded in the field).

2. What they found

• 61 pine marten scats were found in 19 of the 52 cells, an average of 2.17 scats per kilometre surveyed.
• More scats were found in cells with permanent watercourses, more deciduous forest, more mature pine forest and rocky areas.
• Fewer scats were found in cells with more brushwood and at higher altitude.
• Young pine forest, slope and terrain orientation showed no link with scat abundance.
• Cluster analysis split the cells into two groups: 25 cells with many scats, much deciduous and mature pine forest and little brushwood, and 27 cells with few scats, little forest and much brushwood. The groups differed significantly.
• In a preliminary trapping campaign in part of the study area, 48 small mammals were caught. Brushwood and deciduous forest had the most small mammals; mature pine forest had few.

3. What they concluded

• Pine martens seem to prefer forest habitats in winter, as found elsewhere in Europe.
• Habitat use seems largely set by how many prey animals there are and how easy they are to catch. Deciduous forest offers plenty of food. Brushwood also has many small mammals, but prey may be harder to find and catch there. Mature pine forest has fewer prey, but they may be easier to catch.
• Forest and rocky areas also give shelter from harsh weather and protection from predators; pine martens make their homes among rocks and in hollow tree trunks.
• Martens were more common in the warmest, lower areas, unlike earlier studies that found them choosing colder areas in winter.
• The link with watercourses had not been reported before in Spain and might reflect more and more varied food there.

4. How tracking was or was not used

The whole study rests on finding and identifying pine marten scats along walked transects. Scats were identified by size, appearance and smell, and their locations were marked on 1:25,000 maps. Scats of the similar beech marten were ruled out because beech martens were not found in the area. No other tracks or signs and no trailing are reported.

5. Tracker or observer certification

Not reported. All transects were walked by a single observer, but the paper does not say who this was or how their scat identification was checked. The results depend entirely on correct scat identification. A. Gago, T. Pérez, B. Barrio and S. Rosellini are thanked for help with fieldwork.

6. Other technologies, skills or innovations

• Grid-based scat survey with an abundance index that corrects for unequal survey effort between cells.
• Camera traps and visual surveys (unpublished) used to check that beech martens were absent, so that scats could be assigned to pine martens.

7. Implications for conservation (from the paper)

• Studies of habitat use are essential for managing pine martens in Spain and securing the species’ long-term conservation.
• Deciduous and mature pine forests, rocky areas and watercourses appear to be important winter habitat in this park.