For the Birds Radio Program: Tropical Rain Forest

Original Air Date: March 14, 1988

How does tropical deforestation affect our birds?

Duration: 4′00″


(Recording of a Wood Thrush)

A week ago I attended a conference at the Bell Museum of Natural History in Minneapolis about tropical deforestation and how that problem is connected to us here in Minnesota and Wisconsin. The loss of forest lands throughout the tropics is extremely serious, yet solutions are difficult—3 billion people live within the tropical zone. Even without slashing and burning jungles for agriculture and cocaine production, vast amounts of precious wood goes up in smoke every day as cooking and heating fuel for these people.

As we lose tropical forests, so go tropical species— currently at an estimated rate of at least one species every day. So the tone of the conference was grave. Yet there was also hope—several projects are being undertaken to research the problem and to set aside large tracts of forest as preserves, using novel ways for financing.

A spokesman for Norwest Bank talked about Norwest’s effort to help a Costa Rican mahogany door manufacturer to work out harvest methods that minimize long-term damage and replenish the resource. More and more U.S. companies and financiers are realizing that when the forest is gone, any hopes of getting Third World countries to repay their debts will vanish—so encouraging action is being taken on that front.

If the entire rain forest were lost, which at this rate may happen in the next century, what is at stake for Northlanders? Two of the most obvious problems are serious changes in global climate and the chemical balance of our atmosphere. Also, the loss of species is a loss of biological diversity. Plants and animals which have already been lost might well have provided humans with food, pharmaceuticals, and other valuable resources. Just think–a cure for AIDS may well be locked up in the leaves or roots of some tropical plant. The tropical forests are home to several thousand bird species, compared to the mere 700 species in the entire United States and Canada combined. Many tropical birds are endangered, and an inestimable number are already extinct.

For me, though, the saddest loss from deforestation is the loss of habitat for our own Northland birds. The tropical forests of Central and South America provide winter homes for about 332 species of North American birds. Many of the birds that we consider true Minnesota birds are actually tropical species which visit the Northland simply to breed before returning to their tropical home. Warblers which are here for less than three months of the year spend the vast majority of their days in the tropics. Broad-winged Hawks—the species which migrates over Hawk Ridge every fall in huge kettles— winter almost exclusively in tropical countries—as does our hummingbird, kingbird, flycatchers, orioles, tanagers, and most of our thrushes, vireos, and warbler species.

Kevin Winkler, a graduate student at the University of Minnesota, studies Wood Thrushes on their tropical wintering grounds. Through banding and radio telemetry studies he found that thrushes maintain individual winter territories. Even as I speak, some of their territories are being destroyed, leaving them homeless. Winkler demonstrated that Wood Thrushes that are not on territories in his study area suffer higher mortality rates than those on territory. Small wonder that people are finding population decreases in some of our most treasured Northland birds.

(Recording of a Wood Thrush)

This is Laura Erickson, and this program has been “For the Birds.”