Local View: Protect beloved Northland birds by protecting our atmosphere
Standing on the ground and looking skyward, the Earth's atmosphere seems limitless; so we may have doubts about human-caused climate change. Pollutants appear to readily dissipate in this vast space.
But an entirely different picture is evident when we view Earth from space. Then we see the atmosphere as merely a thin blue line surrounding our planet. If Earth were an apple, the thickness of the atmosphere would be no more than the thickness of the apple's skin.
Sharing this thin layer with us are the birds, whose songs, soaring flights, and presence at our feeders nurture our souls. Most of us are casual observers of birds, but more than 47 million Americans consider themselves birders. And birders are way ahead of political leaders in recognizing the importance of wildlife conservation.
The National Audubon Society recently published a report on birds and climate change. The report used three decades of observations from the Audubon Christmas Bird Count and the North American Breeding Bird Survey to develop models that relate the current distribution of bird species to climate. These models include maps of how individual bird species' ranges may be expected to expand or contract in this century based on three different climate scenarios.
The scientists concluded that 314 of the 588 bird species modeled (53 percent) would lose more than half of their current geographic range in all climate scenarios. For 126 species, this loss in range is to occur without accompanying range expansion. The conclusion is that many of the birds we have been accustomed to seeing in our backyards will disappear.
The most seriously threatened birds are classified as climate-endangered, meaning a projected loss of over 50 percent of their current range by 2050 under all climate scenarios. Climate-endangered birds are not necessarily threatened with extinction.
In Minnesota, over half of our bird species are endangered or threatened by climate change. Of 298 birds, 73 are at risk of severe decline by 2050. Another 93 species are at similar risk by 2080.
Many water birds are classified as climate-endangered, including common loons, mallards, and others that we typically see on our lakes and ponds. If you have a lake cabin, imagine your children's summers without these birds.
More specifically, Audubon's climate-suitability maps forecast that the common loon will lose 56 percent of its current summer range and 75 percent of its current winter range. In both seasons, the ranges likely will shift to the north. The models indicate Minnesota almost certainly will lose its iconic loons in summer by the end of the century.
Among climate-endangered birds of prey are ospreys and great gray owls. Endangered upland game birds include ruffed and sharp-tailed grouse. Some winter residents, including pine grosbeaks, are also climate-endangered. In this century, northern Minnesota may lose 14 species of warblers. Warblers are important in controlling forest pests.
Migrants usually will have a harder time than resident birds. Long-distance migrants are particularly vulnerable, partly because habitats and the foods they need during migration may shift and not be available when needed. In addition, migrants may arrive at their breeding grounds after their major food supplies have passed peak abundance. In some cases, migration routes may become longer.
Migrants also may encounter new parasites, competitors, and predators to which they are not adapted. For neotropical migrants, the Audubon study does not account for habitat changes in their winter ranges, so projections for these birds may be conservative.
If we care about preserving our Northland birds for their ecological, spiritual, and sporting values, then we must also protect that thin blue line.
David Gerhart of Duluth has a doctorate degree in aquatic ecology from Cornell University and has published and reviewed manuscripts for scientific journals in the fields of ecology and biochemistry. This commentary was reviewed by Duluth bird expert and author Laura Erickson before being submitted to and edited by the News Tribune.