There would seem, at first, to be many alternatives to killing. Besides mesh and electric fences, there are nets to cast over trees and gardens; foul scents with names like Not Tonight, Deer; and home remedies like sprinkling cayenne pepper around the tomatoes and dumping used cat litter into woodchuck holes. There are scarecrows in the north and fake alligators in the south, and household pets to scare predators away or to do the gardeners’ dirty work. There are capture-and-release traps.

But none of these methods work all the time, and some, depending on the species you are trying to catch and the area in which you live, may not even be legal. The New York State Environmental Protection Law, for example, forbids anyone but a state Nuisance Wildlife Control Operator from transporting a wild animal, which puts the kibosh on the use of capture-and-release traps.

Trapping and moving animals may not be in their best interests, either: a backyard suburban squirrel, transported to a forest, is easy prey for hawks and foxes, said John Hadidian, the director of urban wildlife programs for the Humane Society of the United States and the primary author of “Wild Neighbors: The Humane Approach to Living With Wildlife.” (The book suggests tolerance as its first choice for everything from bats to rats.)

And releasing an animal in a more familiar setting may not be in your neighbors’ best interests.

“We have yet to find anyone in outlying areas who says, ‘We love raccoons, please bring your humanely trapped critters here and let them go,’ ” says Wendell Martin, a retired engineer who has a five-acre garden in Meridian, Idaho, near Boise. Raccoons have uprooted and upended his water lilies to find snails. Mr. Martin finally borrowed a .22 and shot them. It was not an ethical problem for him, he says  the animals are overpopulated in his area  but it was not easy emotionally. (This year there seem to be fewer of them, and he has been trying to protect his plants with wire mesh.)

Then there are the difficulties that can arise when transporting a wild animal.

Jessica DuLong, a Brooklyn writer and marine engineer, managed to grow a fruit-bearing cherry tree on her roof, but even in the wake of what she calls the Great Cherry Massacre of 2007 she was not interested in punishing the squirrels who preyed on it. She trapped one in a live animal trap and set out to Prospect Park with good intentions.

Unfortunately, the squirrel had no way of knowing this. It threw itself against the walls of the cage with such ferocity it cut itself; it defecated; it ran back and forth inside the long cage in a frenzy so that the cage flipped up and down like a manic miniature seesaw. New Yorkers, seeing a fluffy tail in distress, yelled at the human involved.

“This entire class of preschool kids was out in one of their little preschool wagons, and the squirrel is looking rabid and bleeding at the mouth,” she says. “It was not what I had in mind when I started this humanitarian project.”