Causes of Mortality

A grizzly paw print

Understanding the causes and rates of mortality are fundamental to conservation, especially for long lived animals like grizzly bears that have low reproduction.

The main causes of death in grizzly bears are (in no particular order): natural causes, hunter kills, control kills in perceived defense of life and property, self-defense kills, and road and railway strikes.

Human caused mortality were further categorized by McLellan, Hovey and Woods as:

1) Legal hunting (Until 2017)

2) Malicious (Animal shot and left for no reason)

3) Management problem or Control kills (bear near building, camps, livestock & killed or removed by a wildlife official)

4) Citizen’s problem (citizen shot bear for reasons stated in #3)

5) Self defense

6) Poaching – Illegal hunting

7) Accident (such as a vehicle collision)

8) Unknown

An important finding of the SRGBP is that non-hunter, human caused mortality has increased greatly since the 1980’s. Lamb et al (2016) found that between 2006 and 2014, 68% of mortality in their study area (which encompassed the whole of the SRGBP study area) were due to non-hunting sources. Of the non-hunting human caused mortality 54% were due to vehicles and trains, 33% due to control kills and 13% illegal kills. This high mortality from non-hunting sources created a mortality sink for bears along the Highway 3 corridor in the center of the study area. This work demonstrates how important it is to identify causes of mortality to become better informed in order to create solutions to bear-human conflict