Introduction

Laura Pedrick for the New York Times

Ever since Canada geese flew into the engines of a US Airways jet in January 2009 and forced it to land in the Hudson River, New York City authorities and the United States Department of Agriculture have been working to thin the growing population of the migrating birds.

Last summer, wildlife biologists rounded up 1,235 Canada geese at 17 sites around the city and killed them. More recently, much to the consternation of animal-rights activists and some Brooklyn residents, nearly 400 geese and goslings in Prospect Park were packed into crates and taken to a nearby building where they were gassed with lethal doses of carbon dioxide.

City officials say that with three big airports to worry about, the proliferation of Canada geese is a safety concern, not just a nuisance, and requires drastic action.

Is gassing the best way to get rid of the geese, or reduce their numbers? Are there other methods that work just as well?