Causes of mortality

Understanding the causes and rates of mortality are fundamental to conservation, especially for long lived animals that have low reproduction. Understanding the cause of death of grizzlies as well as the trend in resource availability enables managers to make well informed decisions based on population trend.

The main causes of death in grizzlies are: natural causes, hunter kills, control kills to defend life and property, self-defense kills, and road and railway strikes.

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

1) Legal hunting

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

3) Management problem (bear near building, camps, livestock & killed or removed by a wildlife official) – These are also known as control kills.

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

McLellan, Hovey and Woods (1999) found that legal harvest accounted for 39-44% of grizzly bear mortalities within BC. CHECK THIS STATEMENT-how did they estimate unreported mortality? Control kills or citizen problem kills were a major cause of mortality in several of the jurisdictions of the study. 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 mortalities 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 mortalities 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 come up with mitigations and solutions to bear-human conflict.