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Bear Update: Cub attacked by another mother bear



Black Bear Researcher

On the evening of July 3 rd I witnessed a mother black bear physically attacking another mother bear’s cub. This is the first such observation in my 22 years of black bear study.

I have seen adult males attempt and successfully kill cubs and coyotes attempt to kill cubs, but never any physical (contact) aggression by a mother to another mother’s cub-of-the-year.

Adult females in Whistler do not maintain exclusive territories and rarely fight but rather, maintain hierarchies of social ranking by age (size and experience) and dominance. Females will chase females and communicate using body language/posturing, vocalization, and scent-marking on mature trees and sign-posts, etc. While I have observed adult females chasing each other from feeding patches and breeding ranges and less frequently with short bursts of paw-swats or biting, I have never observed a mother attacking another mother’s offspring (cub or yearling).

During an evening (6-9 p.m.) bear viewing tour, I came upon a situation near Crabapple Creek at the top of the Fitzsimmons Chair where Kayley, a resident mother, and her 18-month-old yearling son were grazing 30 metres from the edge of the ski trail. Another resident mother, Jeanie, was treed nearby with her 5.5-month-old son in a mature cottonwood tree. Jeanie’s daughter was treed separately in another cottonwood tree 20-metres upslope. A bike patroller nearby reported that Kayley charged and chased Jeanie to the ski trail edge and, possibly in confusion, Jeanie’s cubs became separated, or they may have climbed the trees before she treed. From 20:17 hours when I arrived, the following events unfolded that led to two physical attacks by Kayley on Jeanie’s 5.5-month-old daughter:

20:17 hrs. Kayley and yearling son grazing 30 metres from Jeanie treed, 20 metres up cottonwood with her son 5 metres above in same tree and her daughter 20 metres upslope and 20 metres high in another cottonwood.

20:21 hrs. Kayley approaches Jeanie’s tree — son climbs higher vocalizing stress — Jeanie snorting and blowing while slapping branches. Kayley backs off and paces with yearling at her side.

20:40 hrs. At this point I left to return clients to valley at end of tour.

21:11 hrs. I returned to find Jeanie and single cub as before treed but now Kayley treed with yearling 1 metre above her on a branch and Jeanie’s daughter on the same branch as the yearling only 1 metre apart. Cub was bawling distress.

21:15-21:46 hrs. Jeanie climbing down tree and pacing around base stressed. Son remains treed above her and is vocally stressed. Daughter extremely stressed vocalizing loud, drawn out bawling. Kayley and yearling remain where they are in tree 1 metre below Jeanie’s daughter.

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