No, you shouldn’t have to worry about bats in your yard as long as they don’t make their way inside your house. Typically, bats hang around backyards in order to consume bugs, especially if they’re located in the U.S. Bats that are native to North America can consume more than 500 bugs per hour, so they may actually benefit your yard if mosquitoes are prevalent.

It can be difficult to know what type of animal is in your attic until you see it. But several clues can help you narrow down the suspects:

• Sounds: Smaller animals like rats and mice make scurrying and tapping/gnawing sounds. Larger animals like raccoons and opossums make louder clambering noises. Also, note when animals are noisy: Squirrels are active during the day, while rats are busiest at night.

• Droppings: Rats and mice leave small, rice-shaped droppings (the rat’s version is significantly larger). Bigger droppings belong to larger critters like raccoons. As long as you’re not squeamish, an image search can help you identify what you’re seeing in your attic.

When in doubt, take photos of damage or other evidence and show them to an experienced pest control pro.

Numerous predators kill hornets, including frogs, birds, lizards, bats, spiders, and hedgehogs. Some larger predators, including rats, skunks, and racoons, will occasionally attack a hornet nest in order to eat the larvae inside. These natural predators typically don’t eat enough hornets to make them an effective form of hornet control. 

The lifespan of a bird's nest depends on the species. The building process can take from two days to three weeks. Once built, the nesting period for baby birds can last from two to ten weeks before they leave the nest. While most young birds are ready in two to six weeks, some predatory species may need up to two and a half months. Some species nest four to five times per year, so a nest could remain in use for several months. For specific information about a particular nest's longevity, it is best to consult a wildlife professional.