There’s an old saying: It’s not the size of the dog in the fight, it’s the size of the fight in the dog.

Luna “the Tuna,” as her humans call her, proves that saying to be true.

“She’ll boss you around,” said Luna’s owner, Jordan Courtney.

Despite standing only 6 inches tall, Luna regular enforcer on her block in Castle Rock, Colorado. She’s the first line of defense for the Courtney family, morning, noon and night — even when a bear wanders into the yard.

Courtney said her mother took Luna outside in the middle of the night on Wednesday, unaware there was an unwelcome visitor near their home.

“Then Luna went racing off, barking, and my mom didn’t know what she was barking at,” Courtney said.

Video caught by their neighbor’s security cameras revealed that Luna had spotted a bear, and fearlessly chased it across the adjacent yard.

“It was just comical, seeing this little doggy chasing after a full-sized bear,” Courtney said.

Luckily, Luna wasn’t injured during the confrontation. It’s unclear, meanwhile, if the bear will think twice about coming back to the block.

“She is protective of her family,” Courtney said of Luna. “She just wanted to protect the home front.”

The Colorado Parks and Wildlife said black bears in the state are entering hyperphagia, a stage in which they try to eat as many calories as they can — sometimes over 20,000 per day — to fatten up for the winter. As bears start to prepare for hibernation and hunt for food, officials warn that residents may see more bear activity in urban areas.

For protection, experts say bear-proofing your home is essential for your own safety.

“Simple changes in human behavior can reap big benefits,” said wildlife biologist Dr. Stewart Breck of the National Wildlife Research Center. “If people keep their trash and other potential food items, like birdseed and dog food, off-limits to bears, not only will they protect their homes and property from bear damage, but they’ll also protect bears.”

Tips for bear-proofing your home include:

  • Keeping garbage in a well-secured location.
  • Only putting out garbage on the morning of pickup.
  • Cleaning garbage cans regularly to keep them free of food odors: ammonia is effective.
  • Using a bear-resistant trash can or dumpster.
  • Not leaving pet food or stock feed outside.
  • Attracting birds naturally with flowers and water baths instead of bird feeders, which are a major source of bear/human conflicts.
  • Not hanging bird feeders from April 15 to Nov. 15.
  • Not feeding other wildlife including deer, turkeys or small mammals.
  • Not allowing bears to become comfortable around your house. If you see one, yell at it, throw things at it, make noise to scare it off.
  • Securing compost piles. Bears are attracted to the scent of rotting food.
  • Cleaning the grill after each use.
  • Cleaning up thoroughly after picnics in the yard or on the deck.
  • Keeping rotting fruit from accumulating under fruit trees.
  • Keeping livestock animals in a fully covered enclosure. Constructing electric fencing if possible.
  • Storing livestock food indoors, keeping enclosures clean to minimize odors, and hanging rags soaked in ammonia and/or Pine-Sol around the enclosure.
  • Installing electric fencing (where allowed) around beehives, if you keep bees.
  • Talking to your neighbors and kids about being bear-aware.
  • Keeping garage doors closed.

More tips for bear-proofing your home and bear-safety guidelines can be found at the CPW’s website.