corn20harvest.jpgJanuary 21, 2009
by Dennis T. Avery

Did global warming dump U.S. Airways flight 1549 into the Hudson River by attracting more geese to New York airports? Time Magazine says yes. Time notes a four-fold increase in airplane bird strikes since 1990, and blames global warming and destruction of wild bird habitat for the increased collisions.

Time reached the wrong conclusion. Research indicates we should blame the prosaic corn harvester-and perhaps our attempt to expand corn production for biofuels. Canada geese numbers have increased five-fold since 1970 for one overwhelming reason -farmers’ expanding use of those big corn picker-shellers. The big bright-colored harvesters now roar across the fields every autumn, picking the ears and shelling the corn kernels. With millions of tons of loose corn, some inevitably trickles to the ground, where the geese cheerfully snack it up.

Canadian researchers found the geese had switched their food supply almost entirely since 1970, from a diet of marsh plant rhizomes in winter and early spring to eating mostly corn and young grass shoots.  The marshes aren’t overgrazed, because the extra geese are feeding in fields and pastures.

When I moved to the Shenandoah Valley in the late 1980s, North Carolina goose hunting guides were protesting that northern states had “stolen” their geese. However, the geese that used to travel clear to North Carolina to get marsh grazing were simply staying to pick over Northeastern corn and soybean fields.

The latest trend among the Canadas is not to move at all. Resident geese now make up two-thirds of our goose numbers, up from 18 percent in 1979. These non-migrating geese are a particular problem because they tend to flock and graze around airports (and golf courses).

The modest global warming between from 1976-1998 may have encouraged such sedentary geese. However, the earth has cooled sharply in the past two years, and NASA says the Pacific cool phase now predicts global cooling, perhaps until 2030. Don’t bet that the Canada’s will migrate back to the North with the lower temperatures, however. The winter grain is still free, and the otherwise-annoying dogs are all on leashes.

Meanwhile, farmers have been planting still more corn, on every possible corner of the eastern seaboard, to get their share of those ethanol subsidies. Corn planting expanded about 50 percent in the mid-Atlantic States from 2002-2006, according to Virginia Tech, with comparable increases in New York and Pennsylvania.

This poses an urgent need for more and better bird-strike prevention. Golf courses use trained Border Collies and Shetland Sheep dogs to annoy the Canadas. Thanks to the dogs’ enthusiastic persistence, that works. But we can’t have dogs running loose across the airports. And we can’t hunt in populated areas.

Never mind wailing about global warming, it’s time for more real goose research.

DENNIS T. AVERY is an environmental economist, and a senior fellow for the Hudson Institute in Washington, DC.  He was formerly a senior analyst for the Department of State. He is co-author, with S. Fred Singer, of Unstoppable Global Warming Every 1500 Hundred Years, Readers may write him at PO Box 202, Churchville, VA 24421 or email to

Sources used in this article:

Giles Gauthier et al. (2005) “Interactions Between Land Use, Habitat Use, and Population Increase in Greater Snow Geese:  What are the Consequences for Natural Wetlands?”, Global Change Biology, Vol 11. pp 856-868.

R. Dolbeer, J. Seuber. “Canada Goose Populations and Strikes with Civil Aircraft: Positive Trends for the Aviation Industry” Proceedings of the 2006 bird Strike Committee USA/Canada, 8th Annual Meeting, St. Louis, MO