Protected areas may provide insufficient protection for carnivores such as bears (Ursidae) with large home ranges and extensive seasonal movements. Even in protected areas, harvest can be the main cause of mortality if parks are small or individuals live close to the boundary. At >7,600 km², Algonquin Provincial Park (APP) is the largest protected area in southern Ontario, Canada, yet wolves (Canis lycaon c.f.) experienced increased mortality when leaving APP to hunt white-tailed deer (Odocoileus virginianus). American black bears (Ursus americanus; hereafter, bears) also undertake seasonal movements, and may incur increased risk of harvest related mortality if they leave the park. We fitted 72 bears with Global Positioning System or Very High Frequency radiocollars during 2006–2014 to determine overall and cause-specific mortality rates, and whether risk of mortality changed when bears left APP or during years of low natural food availability. Further, we compared the abundance of resident bears with harvest rates in Wildlife Management Units (WMUs) surrounding APP to determine whether harvest was higher in areas surrounding the park compared with WMUs farther from the park boundary. Hazard analysis showed annual mortality for radiocollared bears in APP was 15%. Harvest mortality was double that of all other causes combined. Bears were 7 times more likely to die outside the park. Years of lower natural food availability inside the park, or higher red oak (Quercus rubra) availability outside the park did not significantly alter the risk of mortality. Male bears were 6 times more likely to be harvested than females, and 4 times more likely to die from other causes. High harvests of bears in WMUs near APP contrasted with low abundance of resident bears, suggesting that APP acts as a source population for harvest that occurs near park boundaries. Meaningful maintenance of the integrity of bear populations in protected areas should be undertaken at the landscape scale.