Fern Bendio, Brigham Young University- Provo

To determine the minimum canine bite force and claw force of polar bears (Ursus maritimus) relevant to human–bear interactions, we measured the force required to reproduce damage created by live bears. High-density polyethylene enrichment toys previously used by captive polar bears were examined for puncture marks and claw scratches. We quantified damage depth using microscopy. Stainless steel replicas of a polar bear canine tooth and claw were then tested with a calibrated tensile testing system until the same damage depth was reproduced. We found that a mean force of 1,444 newtons was required to replicate canine puncture depth and a mean force of 987 newtons was required to replicate claw scratch depth. These values represent minimum force estimates because the bears were well-fed and not motivated to exert maximal effort. We conclude that although polar bears possess substantial bite and claw strength, limitations in jaw gape relative to adult human head circumference make molar crushing unlikely during most interactions. These results suggest that craniofacial injuries and material failures are more likely caused by canine scraping and clawing than by molar compression. This noninvasive method provides in vivo force estimates for a large carnivore and offers practical data that may inform bear-resistant product design, injury interpretation, and management strategies aimed at reducing human–bear conflict and supporting coexistence.