Wherever you are in the U.S., a coyote may be taking up residence less than a mile away. If you live in the city, you’re more likely than your rural cousins to encounter raccoons. And regardless of geography, you probably share your home with dozens of species of insects and spiders. These facts...

Standing in the street and admiring each other’s gardens one day, Sherrie Pelsma and her neighbor made a discovery: They’d become hosts to a buzzing block party. “We could actually see the air traffic of bees and butterflies crossing the street between our two habitats,” recalls Pelsma. “I said,...