Faeces were collected monthly along transects in 9 areas of the Pisa p
rovince, central Italy, from April 1992 to March 1993 (total km walked
= 982). An index of fox abundance (n of faeces per km) was computed.
It was negatively influenced by rainfall in the 20 days preceding the
transect, but was unrelated to the percentage of plant material in the
diet. Differences among areas (averages from 0.338 to 2.966 faeces pe
r km) were significant (p < 0.0001) and consistent throughout the year
. Faeces were randomly distributed along the transects. The index may
therefore provide an efficient and inexpensive method to evaluate rela
tive abundance of foxes, but comparisons should include only areas and
periods with similar rainfall. Seasonal population fluctuations are n
ot detectable. Best results may be obtained when rainfall in the 20 da
ys preceding the transect did not exceed 50 mm.