Just like weeds are plants growing in the wrong place, vermin are animals in the wrong place. Most often, in the context of a city like San Francisco, that would be in or near our homes, interfering in some way with our lives. When they’re up in the forest, they’re wildlife, or just plain animals.
Living in San Francisco, we’re fortunate to have wildlife in our midst. Raccoons. Skunks. Opossums. Rodents including gophers and voles and rats and squirrels. Reptiles of various kinds. Foxes. Coyotes. Bats. We’re also fortunate to have people who watch some of them and post information and pictures. The excellent Coyote Yipps blog has great photographs of coyotes that live in our city; it’s run by Janet Kessler, the Jane Goodall of San Francisco’s coyotes. Jennifer Krauel has a Masters thesis and a website on San Francisco’s bats. (If you have other references, send an email to email@example.com, or leave a comment.)
We don’t know what lives in Mount Sutro Cloud Forest (it hasn’t been studied). But the animals that live there depend on the understory of blackberry thickets for cover. Snails and insects attracted to these thickets are a food source, as are the berries of the blackberry and the ivy, in season. Rodents such as gophers are a foundation species for a whole ecology.
So what happens to these animals when the understory is ripped out and poisoned with herbicides? Some may be able to move, but many animals are territorial. They cannot move into other territories any more easily than you could move into your neighbor’s home if your house was destroyed. Instead, they seek unoccupied territories. These may well be homes and gardens around the “Demonstration areas”; they’re open territories because we work to keep them that way. We don’t really want to share our homes with random wildlife. That’s when they become vermin.