Why Do Dogs Bark at a Full Moon?

Maybe he just has more to say when the moon is full.
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Every blade of grass is visible at midnight, wild critters scurry long past their usual nesting times, and all the dogs in the neighborhood are barking. It's the full moon and many pet guardians report their usually placid canines channeling their wolf ancestors' spirits during these well-lit nights.

More Light

One reason dogs may bark more during a full moon is simply because there is more light. More light means they see more of what's happening. On a darker night, Rover might not see the squirrel dart up the tree just after midnight. But during a full moon, he's going to see the squirrel and he's going to bark. Just like humans, the light shining in the window may keep Rover awake. Because he's looking out the window instead of curled up in his dog bed, he's going to be even more likely to see the squirrel's midnight rendezvous, and being a good dog, he's going to have to tell you about it.

More Activity

Because it is lighter outside during a full moon, there is more activity. It's not just the squirrel who darted down the tree in the wee hours. Human activity increases and Rover is going to bark when the neighbors decide to go for a moonlit stroll at 11 p.m. He's going to bark at the birds and rodents who are about their business as if it's the middle of the day. If you live in a rural area, his coyote cousins may be howling -- influenced by the same factors as Rover -- and he will feel compelled to answer their calls.


Canines -- dogs, wolves and coyotes -- bark and howl to communicate. That's why Rover has to bark back when he hears his cousins howling in the distance. Dogs bark and howl to let other canines know where they are. They bark to give warning to other canines and to their humans. And -- it seems at least -- they bark and howl just to express themselves. Because it is lighter and there is more activity during a full moon, it may just be that dogs have more to say than on darker evenings.

Do They Really?

Scientists question whether dogs really bark more during a full moon or whether people just notice dogs barking more during a full moon. Research does indicate that the full moon has some bearing on animal behavior. A 2007 study conducted by Colorado State University found dogs are nearly 30 percent more likely to be brought to an emergency veterinary clinic during a full moon than at other times of the month. But this may simply be because it is lighter outside and more creatures -- including humans and their dogs -- tend to be out and about when the moon is full.

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