July 22, 2013

Night of the Grizzly Facts

  • Grizzly bears are near-sighted but they make up for it with their amazing sense of smell which is actually seven times stronger than a bloodhound.

  • Despite recent scientific evidence that grizzly bears are definitely active during the night, no comprehensive observation of grizzlies at night has ever taken place; thus, no one knows what is considered 'typical' nighttime behavior.

  • When hunting for newborn elk calves in the open meadows of Yellowstone, grizzly bears move in a characteristic zigzag pattern – locating the hidden elk calves primarily by scent.

  • Recent evidence suggests that grizzly bears may in fact be more successful hunting elk calves at night than they are during the day.

  • Grizzlies are more nocturnal precisely at the time when elk calves are being born in spring – this suggests a possible link between increased nighttime activity and night time predation behavior.

  • Grizzly bears will prey on newborn elk calves before they are old enough to run away. They will also chase and ambush young elk calves who do run or 'flush,' as it's called, with a sudden burst of speed.

  • An elk calf's best defense in its first few days of life is concealment because it lacks the basic agility, strength, and fitness to run away from predators. Its spotted coat gives it natural camouflage and the calves appear to emit very little scent. Calves also stay motionless when they sense danger to avoid being detected.

  • Interestingly, in the Greater Yellowstone Ecosystem, more male grizzly bears were nocturnal than female grizzly bears. No explanation for this difference in behavior is yet available.

  • Grizzly bears also use hearing to hunt – they are attracted to elk bugles and the distress calls of calves. Hearing could also be used by grizzly bears to locate prey at night.

  • Wildlife studies that utilize thermal cameras are relatively new in the field; thermal camera technology, GPS collars, and telemetry all may change what is possible to observe when it comes to nighttime wildlife behavior.

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