One of the beauties of cottage country is being closer to nature. Being closer to nature means being closer to the little critters that like cozy warm and dry homes we build for them. It requires constant vigilance to keep them on the outside.
One easy way is to make sure the obvious openings that we create like the range hood exhaust (shown in the picture) have bars on the windows so-to-speak.
Be sure to purchase all such vents with maximum quarter-inch grates. That will be sufficient to keep the small critters like birds, bats, mice and squirrels from having an easy access.
Also this one has a metal flap in it that open when the fan is on and closes shut when it is off.