Mercury Utility Index

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

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

3. 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

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

2. 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)

C. EASE OF COLLECTION
1. Social structure
5—Highly colonial or gregarious
3—Semi-colonial or semi-gregarious
1—Solitary

2. Accessibility of sampling unit
5—Individuals or nests are easily accessible
3—Individuals or nests are moderately accessible
1—Individuals or nests are difficult to access

3. Ease of capture
5—Low mobility (e.g., nestbound young or eggs available)
3—Moderate mobility (e.g., independently-foraging young)
1—High mobility (e.g., mobile adults available only)

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

5. Federal or state management status in study area
5—Not protected or managed
4—Protected
3—Threatened
1—Endangered

D. QUANTITY OF EXISTING EXPOSURE AND
EFFECTS DATA
5—Substantial data
3—Some data
1—Very little data