Integrated Risk Assessment

“Risk” is defined here as the likelihood that a range can maintain a self-sustaining local population, and the uncertainty surrounding the indicators used in the assessment. The Integrated Risk Assessment for each local population had 2 main components (Tables 6 and 7):

1. A statement about the probability that current range conditions, described in terms of habitat and population conditions, are sufficient to support a self-sustaining population (Table 6). This involved a lines and weight of evidence approach to integrate the three indicators of self-sustainability (see Section Decision rules for integration) and assign each range to one of five likelihood categories of self-

sustainability. These categories represent a gradient of risk based on a modified version of the likelihood scale developed by the Intergovernmental Panel on Climate Change (IPCC 2005.).

2. The uncertainty, or alternatively, the certainty in the Integrated Risk Assessment was assessed using two certainty measures: a statement of certainty that reflects the type of information used to estimate the indicators of self-sustainability (Table 7), and their consistency (described under Section Decision rules for Integration).

A reported lambda measured over at least three years within the last 10 years was assigned a higher level of certainty in terms of the quality of information than a reported trend. A reported lambda measured over less than three years within the last 10 years was assigned the same level of certainty as a reported trend

(Table 7).

Table 6. Likelihood scale for the Integrated Risk Assessment of current conditions.

Probability of the outcome (self-sustaining)

Category of likelihood that the range condition can support a

self-sustaining local population Self-sustainability outcome 1

 0.9 Very likely SS

<0.9 to 0.6 Likely SS

<0.6 to 0.4 About as likely as not NSS/SS

< 0.4 to  0.1 Unlikely NSS

< 0.1 Very unlikely NSS

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Table 7. Level of certainty associated with the availability of demographic data for a range. Data on habitat condition was not included because it was available for and standardized across all ranges.

Certainty statement of evidence based

on availability of demographic data Demographic data available

Much evidence Reported lambda1 _{and population size}

Considerable evidence Reported trend and population size

Some evidence Population size

Limited evidence No demographic data

1. Lambda must be measured over ≥3 years within the last 10 years. A reported lambda that did not satisfy this criterion was treated like a reported trend.

Decision Rules for Integration

A set of decision rules, illustrated in Figure 10, was established for weighting the individual assessments of self-sustainability based on the three (3) indicators and providing one integrated risk assessment. First, a self-sustainability outcome was determined for each indicator using the probability intervals in Table 6. The three individual outcomes were compared to determine if the three indicators of self-

sustainability were in agreement (Step 1). If all three indicators suggested the same self- sustainability outcome (i.e., high agreement as defined in Table 8), the later was

considered as the integrated risk assessment (Step 8). For this situation, the associated likelihood category was based on the indicator suggesting the lowest, more conservative, likelihood of self-sustainability.

Additional steps were taken to resolve disagreement among the indicators and identify the most plausible outcome given available range-specific information. In cases where the three indicators were in complete disagreement (i.e., low agreement as defined in

Table 8), the precautionary principle was applied such that the outcome from the indicator suggesting the lowest probability of maintaining a self-sustaining population was assigned the most weight of evidence, and selected (Step 2) with its associated likelihood category as the integrated risk assessment outcome. For all other cases, Steps 3-7 of the decisions rules were implemented to identify the indicator with the most weight.

Conflicting assessment outcomes resulting from partial agreement (Table 8) between the

habitat and population indicators of population growth (Step 4) was resolved by: 4a. Determining whether there was active predator management on the range.

Active predator management would bias the Pr (λ ≥ stable) population towards high likelihoods of self-sustainability despite poor habitat conditions. When available information suggests predator management, the Pr (λ ≥ stable) habitat was attributed the most weight and used as the indicator of population

growth.

4b. Determining whether the Pr (λ ≥ stable) population was calculated using a lambda measured over at least three years within the last 10 years. This rule was devised to distinguish ranges for which the population indicator of

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population growth was based on a estimates of lambda (λ) that were based on intensive monitoring versus population indicators based on reported trends that are often inferred (see Appendix 7.11). Estimates of lambda can show considerable annual variation due to stochastic events. Three years was selected as the minimum data requirements to produce lambda (λ) estimates with some level of confidence given the assumed levels of error or

stochasticity used in the population modelling to derive the indicators. The Pr (λ ≥ stable) population was assigned more weight and selected for the assessment in such cases, otherwise the Pr (λ ≥ stable) habitat was used. The precautionary principle (Guiding Principle 5) was applied in situations where the outcome from the indicator of population growth (outcome of Step 4a-b) disagreed with the outcome from the indicator of quasi-extinction used to flag the increased risk of extinction for small population sizes (Step 6). The integrated risk assessment was based on (i.e., more weight was attributed to) the indicator that produced the highest risk or lowest probability of meeting the goal of maintaining a self-sustaining population. This was synonymous with adjusting the integrated risk assessment to indicate cases where there might be an increased risk of extinction due to small population size.

As stated previously, in addition to the certainty in the data used (Table 7), the certainty in the integrated risk assessment was further defined through assessing the consistency in the information provided by each indicator for a given range. Consistency was evaluated based on the number of indicators that were in agreement with the indicator assigned the most weight of evidence in the integrated risk assessment (Table 8). The evaluation was conducted only on ranges with all 3 indicators of self-sustainability. As above, the approach used for the certainty statement represents a modified version of that developed by IPCC (2005).

Table 8. Level of certainty in the consistency of information.

Indicator of self-sustainability attributed the most weight of evidence Conditional consistency criteria Certainty statement of consistency of information

Pr (λ≥ stable) Consistent with alternative Pr (_{stable) indicator} λ≥

High agreement

Pr (Nt ≥ Qext) Consistent with the two Pr (_indicators λ≥ stable)

Pr (λ≥ stable) Consistent with Pr (Nt ≥ Qext)

Partial agreement

Pr (Nt ≥ Qext) Consistent with one of the two Pr (_{stable) indicators} λ≥

Pr (λ≥ stable)

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Figure 10. (a) Decision rules applied to inform integrated risk assessment. (b) Elaboration of rules used to resolve difference between the indicators of population growth.

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