From Today's New York Times

To the Editor:

Re “Thinning Yellowstone’s Bison Herd” (news article, March 23):

Yellowstone National Park bison, executed when they migrate outside the boundaries of the park, have plenty of company. Around the world, animal migrations are disappearing because of conflicts with development, agriculture and other human activities.

In the greater Yellowstone ecosystem alone, over half of the elk migratory routes and three-quarters of the antelope routes have been destroyed by sprawl, oil and gas development, and farming.

Earlier this month, NASA released new satellite photographs showing continued illegal cutting of the Mexican fir forests where virtually all of eastern North America’s monarch butterflies spend the winter.

And bird watchers across the United States and Canada face the prospect of a quieter, less colorful spring as a combination of climate change, tropical deforestation, mountaintop mining in the Appalachians and other activities destroys key wintering, breeding and stopover habitats.

The loss of migration is of more than aesthetic importance. Migratory birds protect forests and crops from insect pests; butterflies, bats and other migratory species are important pollinators.

Indeed, migratory animals are useful indicators of the health of the global environment; their safe passage is in our best interest.

David S. Wilcove
Princeton, N.J., March 24, 2008
The writer is the author of a book about the decline of the world’s great animal migrations.