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The general status of a given species was derived
by considering available information relating to a
set of seven criteria that collectively reflect the status
of a (species’) population within specific geographic
areas that is, provinces, territories, ocean
regions, and Canada as a whole. These criteria
were based on definitions used in the Red List
Categories of the World Conservation Union, the
Criteria for Amendment of Appendices I and II (Res.
Conf. 9.24) of the Convention on International
Trade in Endangered Species of Wild Fauna and
Flora (CITES), and the Natural Heritage
Programand Conservation Data Centres of the
Associationfor Biodiversity Information Canada.Criteria
were used as a guide to help determine the
appropriate general status category for a species.
Where possible, representatives from each
province, territory, and federal agency followed
the following definitions of the seven criteria:
- Population size is defined as the current estimate
of the total number of mature individuals capable
of reproduction. Where populations are character-ized
by natural fluctuations, the minimum number
should be used. Likewise, if the population is
characterized by biased breeding sex ratios, it is
appropriate to use lower estimates for the number
of mature individuals that will take this into
account. For many species, a figure of less than
1 000 individuals has been found to be an
appropriate guideline of what constitutes a small
population. It is likely that different definitions of
what constitutes a small population will need to
be developed for different taxonomic groups.
- Number of occurrences is defined as the
estimated number of sites where the species
currently persists. A site occurrence is described
ecologically as a location representing a habitat
that sustains or otherwise contributes to the survival
of a population. A site occurrence will be defined
differently for different species, depending on its
natural history. When a species’ distribution is
extremely limited and there are very few site
occurrences, the species is very susceptible to
any number of disturbances, both predictable and
unpredictable. This criterion is therefore the single
most important factor influencing overall rank when
the number of occurrences is few.
- Geographic distribution is defined as the area
contained within the shortest continuous imaginary
boundary that can be drawn to encompass all the
known, inferred, or projected sites of occurrence,
excluding cases of accidental species. The area
within the imaginary boundary should, however,
exclude significant areas where the species does
not occur. For migratory species, the geographic
distribution is the smallest area essential at any
stage for the survival of the species.
- Trend in population is defined as an estimate
of the change (if any) in the number of mature
individuals over time. Where declines are
indicated, rapidly declining is defined as a
decrease of 50% in the last 10 years or three
generations, whichever is longer. Declining is
defined as a decrease of 20% in the last 10 years
or three generations, whichever is longer. Natural
fluctuations will not normally count as part of a
decline, but an observed decline should not be
considered part of a natural fluctuation unless
there is evidence for this interpretation.
- Trend in distribution is defined as the change
(if any) in the geographic distribution of the
species over time. Where declines in distribution
are indicated, rapidly declining is defined as
a decrease of 50% in the last 20 years or six
generations, whichever is longer. Declining is
defined as a decrease of 20% in the last 20 years
or six generations, whichever is longer.
- Threats to population are defined as observed,
inferred, or projected direct exploitation, harass-ment,
or ecological interactions with predators,
competitors, pathogens, or parasites that may
result in population declines. Extreme threats
are significant, could affect more than half the
population, and are unmitigated. Moderate
threats are also serious but affect less than half
the population or are mitigated by some level
of human protection. Limited threats are less
significant to population viability or are being
mitigated through protective measures.
- Threats to habitat are defined as observed,
inferred, or projected habitat alterations
(loss, conversion, degradation, or fragmentation)
that may result in population declines. Extreme
threats are significant, affect more than half the
population, and are unmitigated. Moderate
threats are also serious but affect less than half the
population or are mitigated by some level of
human protection. Limitedthreats are less
significant to population viability or are being
mitigated through protective measures.
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