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detect a tree dwelling or arboreal species with sampling methods that focus on
the ground, such as camera traps or track surveys). We may have inadvertently
sampled only parts of our study area with certain habitat features, which some
species may avoid and thereby avoid being recorded. Some of these issues can
be counterbalanced by an adequate study design that covers all habitat types
within a study area (to capture species with different habitat requirements) and
the use of complementary survey methods (camera traps, track surveys for
ground-dwelling mammals and transect or spotlight surveys that also capture
tree dwelling mammals). In conclusion, a photographic record is definite evidence

of that species’ presence in the study area during the sampling period, but
conclusions about the absence of a species should be avoided.

5.2.3 Abundance (Recommended for Better Analysis)

The most refined measure for wildlife monitoring is abundance or density
(abundance per unit area). The ideal for any monitoring program is to measure the
total count of all individuals in the population of interest. In order to count
individuals, we have to distinguish one from another – either capturing and
marking or identifying them by their unique features such as spots or stripes (e.g.,
tigers or cats). This depends on whether individuals can be identified based on
camera trap photographs or observation, approaches to obtain measures of
abundance and/or density differ. For example, camera trap settings, post-analysis
settings, and distance between observation points can ensure the data are
independent. Relative species abundance can be calculated by dividing the
number of individuals of one species by the total number of all species.

5.2.4 Distribution

As camera traps are distributed in space, we can also look at the spatial
distribution of the photographic records of a species. Distribution can be studied
at several spatial levels: over large landscapes to investigate a species’ geographic
distribution, but also regionally or locally to get an idea about smaller scale
habitats and space use. We can use information about the locations sampled
(such as habitat type, distance to water, distance to human settlement – anything
that might be important to the species we are studying) to see whether any of
these characteristics influence – positive or negative –

26 GUIDANCE DOCUMENT ON WILDLIFE
IMPACT STUDY FOR IN ENVIRONMENTAL
IMPACT ASSESSMENT (EIA)