Assessment of Potential Indicator Species for Monitoring ...

Criterion 2 - Understanding and Documentation of Ecology
2a Has the home range of the species been described?
Knowledge of a species’ foraging range is necessary to accurately relate its
contaminant burden with known or unknown sources of pollutants. Most species
are much more mobile when not breeding. The size of a home range is usually
relative to the size of the species; larger animals tend to cover larger areas when
foraging. Due to the limited availability of documentation, any information
describing home range size resulted in a score of one. It is also very important to
consider the home range of an indicator species within the context of the
objectives of any proposed contaminant monitoring study.
2b Is the habitat used by the species well documented?
An animal’s choice of habitat is based on cost-benefit relationships which optimally
balance a number of habitat requirements such as availability of food sources, risk
of predation, and adequate protection provided by a shelter. In addition, a habitat
can become less desirable compared to a similar one if it is polluted. The
conspicuous absence of a species from an area where it would be expected to live,
is a definite sign of some environmental disturbance. Organisms may move in or
out of an area if they are more or less tolerant of pollution relative to competitor
species. Knowledge of an animal's habitat requirements is thus very important to
understand why or why not an animal occurs in a certain area. References
describing habitat preferences at the detail of ecosection (sub-regional
ecosystems) or greater resulted in score of one.
2c Is the reproductive biology of the species well documented?
Information on where and when a species breeds is helpful when trying to locate an
animal to collect a particular form of sample. A species received a score of one if
any references to its gestation or incubation periods and/or dates of breeding were
available.
2d Is the migration behaviour of the species well documented?
A migratory species may be exposed to local contaminants as well as those
encountered during its annual route. Therefore, an understanding of its migratory
behavior helps to distinguish between local versus distant sources of contaminant
burdens or effects. Any references describing a species’ migratory behavior (e.g.
spring arrival and fall departure times) resulted in a score of one. Non-migratory
species were also given a score of one. Only in cases where absolutely no
information was available, was a zero assigned.
2e Is there information on the historic abundance of the species?
Historic information on the abundance and distribution of an indicator species is
necessary in order to monitor the long-term effects of environmental contamination.
References to past population estimates (as described in systematic surveys or
sightings in specified areas), prior to 1980 or during the period between 1980 and
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