Q: My husband and I spent substantial time and money to entice bluebirds to our yard. This included a squirrel- ` and snakeproof bluebird house, special tasty food (which entailed keeping mealworms in my refrigerator), available water and other amenities. Then an interloper nested in our bluebird house and laid five eggs. When is it permissible to destroy a nest of undesirable feathered folk? We want bluebirds, not common yard sparrows. — Judy Barrett, Greensboro, N.C.
A: If it were permitted to bust up the houses of creatures deemed insufficiently appealing, who wouldn’t live in fear? Anne Hathaway, perhaps, but we mortals would be on edge. As I suspect you know, you may strive to attract bluebirds, as some people admirably do to protect that species, but you may not smash sparrows’ nests simply because you find those birds “undesirable.”
You also face legal restraints. The Migratory Bird Treaty Act of 1918 protects more than 800 species from assorted rough stuff, including messing about with their nests. And while it exempts the house sparrow — its nest, eggs and young may be removed or destroyed — other sparrows are protected. (You should, of course, consult state laws.)
There are circumstances when ethics allows you to destroy a nest or eggs or even birds themselves if less lethal methods prove futile. Even protected species may legally be destroyed if they pose a significant threat to people, property or the food supply (and proper permits have been obtained).
I consulted a friend and avid naturalist who went further, and persuasively so: “An environmental ethics that considers the big picture compels killing some animals to protect native species and habitat.” But he does not mention your yard.
Update: “We decided to adopt the ‘squatters’ rights’ philosophy and allowed the interlopers to hatch their clutch of eggs,” Barrett e-mailed. “We plan to be more vigilant next nesting period.” She later told me that she would have no trouble destroying a nest under construction but would not tamper with eggs.
Q: I drive to work each day with my wife on a two-lane road full of potholes. From time to time a guy tailgates me. One day I spotted a big pothole ahead and deliberately waited until the last moment to avoid it so he had to hit it. It must have been quite a jolt because he pulled over to check for damage. My wife was annoyed at me, but I think I educated this guy about safe driving. It isn’t as if a bridge washed out and I lured him into plummeting over a precipice. Agreed? — Name Withheld, Long Island
A: I’m with your wife. In ethics, it is not just your actions but your intentions that are subject to scrutiny. Yours were to damage another person’s car — for pedagogical purposes, no doubt, but that’s not much of a justification.
You also fell short by not stopping when you saw the guy pull over; you yourself thought that he could have damaged his car. Rendering aid was not required but would have been commendable.
Write Randy Cohen at Universal Press Syndicate, 4520 Main St., Kansas City, MO 64111, or ethicist@nytimes.com.
