Grizzly Bear Attacks in the USA/Data

Location

Location	Risk Probability (%)	Odds Ratio
Alaska	0.00029	2.9
Yellowstone National Park	0.000037	0.37
Glacier National Park	0.0001	1.0
Other Lower 48 States	0.00005	0.5
Non-Grizzly Area	0.0	0.0

Risk probabilities are based on attack rates per visit or population exposure. Alaska’s rate (0.00029%) is derived from 29% of fatal attacks occurring there (https://www.nature.com/articles/s41598-019-44341-w). Yellowstone’s rate (0.000037%) is based on 1 in 2.7 million visits (https://www.nps.gov/articles/bearattacks.htm). Glacier’s rate (0.0001%) is estimated from regional data (https://www.nature.com/articles/s41598-019-44341-w). Other Lower 48 states have lower rates due to fewer grizzlies (https://www.nps.gov/articles/bearattacks.htm). Non-grizzly areas have zero risk. Odds ratios are scaled relative to Glacier National Park (baseline = 1.0) based on attack frequency data.

  RiskModel: Grizzly Bear Attacks in the USA/Data:location_risk
Calculation: location_risk_probability * location_odds_ratio
    Content: Your location-based risk is about {result}%

Activity

Activity	Risk Probability (%)	Odds Ratio
Hiking/Camping	0.00025	1.0
Hunting	0.00055	2.2
Working Outdoors	0.0002	0.8
Other Activities	0.0001	0.4

Risk probabilities are derived from a 2019 study showing 50% of attacks occur during leisure activities like hiking/camping, 24% during work-related activities, and 22% during hunting (https://www.nature.com/articles/s41598-019-44341-w). Hunting has a higher probability (0.00055%) due to stealth and attractants. Odds ratios are scaled relative to hiking/camping (baseline = 1.0). Probabilities are adjusted to reflect USA-specific data from 2000–2015 (183 attacks).

Brown bear attacks on humans: a worldwide perspective

  RiskModel: Grizzly Bear Attacks in the USA/Data:activity_risk
Calculation: activity_risk_probability * activity_odds_ratio
    Content: Your activity-based risk is about {result}%

Season

Season	Risk Probability (%)	Odds Ratio
August	0.0004	2.0
April-October (except August)	0.0002	1.0
Hibernation Season (December-March)	0.0	0.0

August has the highest attack rate (0.0004%) due to peak human activity and bear foraging (https://www.eagleeyeadventures.com/post/peak-grizzly-bear-attack-season-when-to-be-extra-cautious). Other active months (April–October) have a lower rate (0.0002%). Hibernation season (November–March) has zero risk. Odds ratios are scaled relative to other active months (baseline = 1.0). Probabilities are estimated from North American data (https://www.eagleeyeadventures.com/post/peak-grizzly-bear-attack-season-when-to-be-extra-cautious).

Peak Grizzly Bear Attack Season: When to Be Extra Cautious

  RiskModel: Grizzly Bear Attacks in the USA/Data:season_risk
Calculation: season_risk_probability * season_odds_ratio
    Content: Your season-based risk is about {result}%

Precautionary Measures

Precautionary Measures	Risk Probability (%)	Odds Ratio
Bear Spray and Food Storage	0.00005	0.25
Bear Spray Only	0.0001	0.5
Food Storage Only	0.00015	0.75
No Precautions	0.0002	1.0

Bear spray reduces attack success by 90% (https://www.eagleeyeadventures.com/post/peak-grizzly-bear-attack-season-when-to-be-extra-cautious), and proper food storage reduces attractant-related attacks. Combining both lowers risk significantly (0.00005%). Odds ratios are scaled relative to no precautions (baseline = 1.0). Probabilities are adjusted based on baseline risk from other tables and effectiveness data (https://www.nps.gov/articles/bearattacks.htm).

  RiskModel: Grizzly Bear Attacks in the USA/Data:precautions_risk
Calculation: precautions_risk_probability * precautions_odds_ratio
    Content: Your precaution-based risk is about {result}%

  RiskModel: Grizzly Bear Attacks in the USA/Data:grizzly_attack_risk
Calculation: location_risk_probability * activity_odds_ratio * season_odds_ratio * precautions_odds_ratio/100
    Content: Your overall risk of a grizzly bear attack is about {{One_In_X|{result}}}