Mercury Vulnerability Index

A. EXPOSURE POTENTIAL
1. Primary Dietary Preference
10—Fish
8—Terrestrial vertebrates or aquatic invertebrates
6—Both aquatic vegetation and animals (aquatic or
semi-aquatic omnivore)
4—Both vegetation and animals (terrestrial omnivore)
1—Vegetation

2. Use of industrial or urbanized areas, and areas vulnerable
to acid precipitation
5—Readily inhabits or forages in these areas
3—Will occasionally utilize these areas
1—Avoids these areas

3. Longevity
5—Long-lived (>15 years)
3—5-15 years
1—Short-lived (<5 years)

4. Residency
5—Year-round resident (does not migrate)
4—Migrates within study area
3—Migrates beyond study area (present during breeding)
2—Migrates beyond study area (present during winter)
1—Transient (present during migration only)

5. Social structure
5—Highly colonial or gregarious
3—Semi-colonial or semi-gregarious
1—Solitary

6. Range
5—Present in small part of study area only
4—Present throughout less than half of study area
3—Present throughout about half of study area
2—Present throughout more than half of study area
1—Present throughout entire study area

B. SENSITIVITY
1. Molt
5—Does not molt
3—Molts infrequently (interval of complete molt =1 year)
1—Molts frequently (interval of complete molt <1 year)

C. RESILIENCE OF POPULATION
1. Abundance in study area
5—Rare (Not normally present)
4—Occasional (Presence possible, but not expected)
3—Uncommon (Presence expected, but not a certainty)
2—Common (Certain to be in suitable habitat)
1—Abundant (Numerous in suitable habitat)

2. Distribution outside of study area
5—endemic to study area
3—present outside of study area, but not abundant
1—abundant outside of study area

3. Reproductive potential
5—Low (1-2 offspring per year)
3—Moderate (3-4 offspring per year)
1—High (>4 offspring per year)

4. Age at first breeding
5—6+ years
4—5 years
3—4 years
2—3 years
1—1-2 years