1996). Ungulate browsing surveys can both index population sizes and measure the pressure
these herbivores are exerting on their food plants. In all these cases standard methods of quadrat
sampling can be used to estimate feeding marks.
Advantages and disadvantages
Like dung counts, the measurement of feeding signs is easily done during the day and does not
depend on capturing or seeing animals. For species that have very broad diets and large seasonal
shifts in diet, this method will not usually be the best way to index abundance. The main problem
is to validate independently whether the particular feeding sign that you are measuring is a good
index of abundance.
Biases
If similar species have similar diets, it might not be possible to separate species in the analysis
of relative abundance. If diets vary markedly from year to year depending on the availability of
alternative foods, what works well in one year may give a biased representation of abundance in
other years.
Counting footprints and runways
Tracks of species in soft ground or snoware an excellentway of determining presence and absence.
If standard methods are employed, these counts can be used as an index of relative abundance
Hair tubes and hair catchers 365
In Finland, Korpim¨aki et al. (2002) used snow tracking to index stoat and weasel abundance 1–2
days after fresh snows. O’Donoghue et al. (1997) used snow-track transects to index population
changes in coyotes and lynx in northern Canada. Sand tracking stations have been used to index
dingo populations in Australia (Allen et al. 1996).
Method
Footprints can be assessed actively or passively. Active assessment typically uses scents or baits
to bring animals into the tracking plot, whereas passive assessment uses tracks made by animals
in their daily travels. These indices measure activity as well as population abundance, and are best
used on species for which activity levels are relatively constant at the times of year the counts are
made. The method is to set out plots large enough to provide good tracks, to rake them clean and
revisit them at fixed intervals. For snow tracking the intervals are usually set by fresh snowfalls.
The important point is that old tracks are not confounded with new tracks.
A similar kind of approach can be used for small mammals that make runways in grassland