Black Bear Attacks in the USA/Data
Exposure
| exposure_level | exposure_days | daily_encounter_rate | injury_given_encounter | fatality_given_injury |
|---|---|---|---|---|
|
1 day |
1 |
0.00000955 |
0.012 |
0.025 |
|
10 days |
10 |
0.00000955 |
0.012 |
0.025 |
|
100 days |
100 |
0.00000955 |
0.012 |
0.025 |
The number of days represents the exposure duration in black bear country. The daily encounter rate (0.00000955 or 9.55e-6) is calculated as 1010 close encounters (estimated using similar proportion as grizzlies for black bear interactions) divided by 105.6 million visits in Yellowstone from 1991-2022, adjusted for higher black bear interactions (10,081 total). Injury given encounter (0.012) is 5 injuries divided by estimated 410 close encounters. Fatality given injury (0.025) is based on 2-2.5% mortality rate in black bear attacks. These values are constant across rows as they represent base rates.
- Grizzly bear and American black bear interactions with people in Yellowstone National Park
- A review of upper limb injuries in bear maul victims
Location
| location | location_odds_ratio |
|---|---|
|
Alaska |
3.0 |
|
Appalachian Trail States |
1.4 |
|
Other Bear-Populated States |
1.0 |
|
Non-Bear Area |
0.0 |
Odds ratios are scaled relative to other bear-populated states (baseline = 1.0) based on attack frequency and population exposure. Alaska has higher odds (3.0) due to high black bear density and 3.5 times more fatal attacks than lower 48 states. Appalachian states have moderate odds based on documented attacks.
- Fatal Black Bear Attacks in North America Over the Last 20 Years
- Bear Attacks (U.S. National Park Service)
Activity
| activity | activity_odds_ratio |
|---|---|
|
Hiking/Camping with Dog |
2.0 |
|
Hiking/Camping without Dog |
1.0 |
|
Other Outdoor Activities |
0.8 |
|
Indoor Activities |
0.2 |
Odds ratios are scaled relative to hiking/camping without dog (baseline = 1.0). Hiking/camping with dog has higher odds (2.0) as over 50% of 92 black bear attacks involved dogs. Other activities have lower odds.
Season
| season | season_percentage_attacks | season_months |
|---|---|---|
|
Summer |
50 |
3 |
|
Other Active Months |
50 |
6 |
|
Hibernation Season |
0 |
3 |
Percentage of attacks by season is estimated from North American data, with summer peak. Number of months for normalization, assuming 9 active months.
Precautionary Measures
| precautions | encounter_risk_reduction | injury_risk_reduction |
|---|---|---|
|
Bear Spray and Food Storage |
0.5 |
0.08 |
|
Bear Spray Only |
1.0 |
0.08 |
|
Food Storage Only |
0.5 |
1.0 |
|
No Precautions |
1.0 |
1.0 |
Risk reduction multiplier represents the remaining risk after precautions. Bear spray alone reduces risk to 0.08 (92% effectiveness). Combined with food storage assumes near-complete reduction (0.02). Food storage alone reduces to 0.5.
RiskModel: Black Bear Attacks in the USA/Data:EncounterInjuryFatality
Sorted Parameters:
encounter_risk = {daily_encounter_rate}*{exposure_days}*{location_odds_ratio}*{activity_odds_ratio}*({season_percentage_attacks}/{season_months})/(100/9)*{encounter_risk_reduction}
injury_risk = {encounter_risk}*{injury_risk_reduction} * {injury_given_encounter}
fatality_risk = {injury_risk} * {fatality_given_injury}
Content: Your chance of having a dangerous, close encounter with a black bear is {{One_In_X|{{#expr: {encounter_risk}|compare=RiskLadder }} }}
Your chance of being injured in an attack is {{One_In_X|{{#expr: {injury_risk}}}|compare=RiskLadder }}
Your chance of being killed in an attack is {{One_In_X|{{#expr: {fatality_risk}}}|compare=Micromorts }}
The 100/9 factor in the encounter risk is because 100% of the attacks occur in the 9-month active season (not the 3 months the bears are hibernating).