Where Have All The Birds Gone? ornithologist John Terborgh asked in his book back in 1989. I was reminded of his question early last October when I noticed that the migrants were few and far between and the woods strangely silent.
Then the National Audubon Society released its State of the Birds USA 2004 report. Touted as “the best data available since [Rachel Carson’s] Silent Spring to report on their [birds’] overall health,” the report did little to relieve my fear that bird numbers are diminishing. Based on national Breeding Bird Survey data from 1966 through 2003, the report primarily sums up the status of 645 bird species native to the continental United States that use one of four major types of natural habitat–grass, shrub, forests, or wetland/water.
Until the Breeding Bird Survey was launched by Chandler Robbins and his colleagues at the Patuxent Wildlife Research Center, there was no good data about habitat loss and its effect on birds even though most of the loss of America’s forestlands and wetlands occurred before 1966. Nevertheless, the report concludes, “wetland and forest species continue to suffer from the effects of poor land management.” Furthermore, “poor land use decisions, certain agricultural practices and overgrazing have caused the dramatic decline of grassland and shrub-land birds.”
The Audubon report assigned all species to one of three categories, the green, yellow, or red Watchlists, based on assessments made by four research groups–Partners in Flight, Waterbirds for the Americas, the U.S. Shorebird Council, and the North American Waterfowl Management Plan.
Although habitat loss and mismanagement are the most serious threats to birds, climate change, air and water pollution, pesticides, and collisions with buildings, towers, and wind turbines are also problems.
Grassland birds have suffered the greatest losses. Of 47 species, 10 are on the red Watchlist (those of highest concern), six the yellow Watchlist (those of moderate concern), and 31 the green Watchlist (those of no or low conservation concern). But even some birds on the green list are still experiencing rapid declines, although their survival is not threatened at this time. For instance, both eastern meadowlarks and bobolinks are green list birds, yet since 1966, less than 40 years ago, the former has declined by 66% to about 10 million birds and the latter to 11 million birds, half of its 1966 population. Short-eared owls, on the yellow list, have decreased by 69% to about 2.4 million birds. Dickcissels are also on the yellow list and Henslow’s sparrows on the red. All are grassland birds that live in Pennsylvania, and dickcissels appear on our own state “Birds of Concern” list as a threatened species.
Historically, Pennsylvania was almost entirely covered in forests, but with the clearing of land for farming after the arrival of European settlers, grassland bird species moved in from the Midwest. Today our grassland birds are threatened by overgrazing, frequent haying, invasive plants, and the selling of farm land for development. Ironically, some grassland birds species, such as short-eared owls and Henslow’s sparrows, are finding refuge on reclaimed strip mines.
According to the Audubon report, shrub-land bird species are also in steep decline. Of 107 species, 71 are green species, 24 yellow, and 12 red, giving them the highest proportion of yellow species. Since most of our shrub-land is in the western United States, namely sagebrush and chaparral, most of the threatened bird species are western species. However, eastern shrub-land habitat is also disappearing due to forest succession, overbrowsing by deer, and urbanization, and a few species on the list do live in Pennsylvania, i.e. the blue-winged warbler on the yellow list and the golden-winged warbler on the red.
Birds that need water are also in peril, both in Pennsylvania and in the United States in general. The Audubon list includes wetlands as well as rivers, ponds, lakes, open ocean, and beaches. Of the 268 water and wetland birds, 212 are green, 31 yellow, and 25 red. Once again even many on the green list are of concern, for instance, the northern pintail, which has declined 63% to 7.5 million birds.
Here in Pennsylvania the yellow birds are American black ducks, prothonotary warblers, and American woodcocks, none of which are on our Pennsylvania list. However, nine of our 14 birds of concern–American and least bitterns, great egrets, yellow-crowned and black-crowned night herons, king rails, common and black terns, and sedge wrens–are primarily wetland species.
Nationwide, half of our freshwater wetlands have been destroyed. In Pennsylvania the estimate is 56%. As the Pennsylvania Game Commission’s ornithologist Douglas A. Gross wrote in Birds: Review of Status in Pennsylvania back in 1998, “The loss of emergent wetlands is one of the greatest factors in the decrease in Pennsylvania’s bird diversity and the cause of the decline of many of its most imperiled species.”
Woodland species are also declining, which brings me back to my original question: where have all the birds gone? I see woodland birds in migration on our forested mountain every spring and fall, and many woodland species breed here, but both breeding and migrant bird numbers are down. The Audubon report verifies this. Of 164 woodland species, 71 are green, 24 are yellow, and 12 are red.
Once again, even a green species, such as the pine siskin, is in steep decline, having dropped by more than half since 1966 to 22 million birds. Wood thrushes are on the yellow list–down to 14 million, again half as many as in 1966. The cerulean warbler numbers are even worse, less than a quarter of what they were, at a total of about 560,000. Worm-eating warblers, which also nest on our mountain, are on the yellow list, along with Kentucky, Canada, and bay-breasted warblers and red-headed woodpeckers. Still on the green list, but in declining numbers, are Louisiana waterthrushes and scarlet tanagers.
Woodlands, according to the Audubon report, are threatened by “unsustainable logging, plantation forestry, overgrazing by deer or livestock, new tree diseases, invasive species, conversion to agriculture, too-frequent or too-scarce fire, resource extraction, urbanization, and fragmentation by roads and utility lines.” Most of these threats are all too familiar to those of us concerned about conservation in Pennsylvania. Could it be that the growth of population in nearby valleys, the increase in roads and vehicles, the erection of cellphone towers, and the unsustainable logging by many of our neighbors on our mountain have contributed to declining breeding bird numbers here?
The Audubon report concludes with an estimate of North American bird species that have undergone the greatest population declines from 1966 to 2003. At the head of the list is the rusty blackbird, sustaining an unbelievable 97.9% loss, followed by Henslow’s sparrow at 96.4%. Other birds on the list that breed in Pennsylvania is number 7, short-eared owl (80.3%), followed by cerulean warbler (79.6%). Loggerhead shrike is number 10 (77.1%) and is also on Pennsylvania’s Birds of Concern list. Number 11 is grasshopper sparrow (also 77.1%), number 15 is field sparrow (68.8%) and number 16 northern bobwhite (67.6%).
Some of the declines are bewildering such as that of rusty blackbirds. They have a vast breeding range throughout most of the boreal region of Canada and Alaska so Partners in Flight scientists think that the loss of forested wetlands where rusty blackbirds spend their winters in the southeastern United States might be part of the problem. The cerulean warblers are most threatened by mountaintop mining in Appalachian forests, but efforts by conservation-minded citizens have so far not halted that pernicious practice.
Species that need periodic disturbances to survive include red-headed woodpeckers, prairie warblers, American woodcocks, and Kentucky warblers, and scientists recommend active management to create such habitats in places where they no longer occur naturally. Northern bobwhites have almost been extirpated in Pennsylvania. They, like many grassland species, need farmland with fencerows, habitat that is difficult to find. Loggerhead shrikes also like hedgerows and occasional trees and shrubs in fields and pastures. After a 50-year absence as breeding birds in Pennsylvania, loggerhead shrikes began breeding in Adams and Franklin counties in low numbers. Grasshopper sparrows, like Henslow’s sparrows and short-eared owls, have benefited from grasslands created on reclaimed strip mines in Pennsylvania.
The threats to birds species and numbers are huge, yet the National Audubon Society is confident that we “can help keep common birds common and reverse the decline of globally threatened species.” If you are a landowner, manage it for birds. We’ve noticed, as our forest has aged, that several mature woods’ species, such as black-throated green warblers, blue-headed vireos, Acadian flycatchers, and winter wrens have started to breed here, and every year their numbers increase. Our forest also provides a haven for cerulean warblers, wood thrushes, worm-eating warblers, scarlet tanagers, and Louisiana waterthrushes. Due to natural periodic disturbances and our maintenance of 40 acres of meadows, we have enough early habitat to satisfy such species as eastern towhees, field and song sparrows, and golden-winged warblers.
Homeowners should make their yards havens for birds, the Audubon report suggests, “by creating a pesticide-free habitat of native plants, providing supplemental food and water, and putting out birdhouses…” They also recommend that folks keep their cats indoors, buy shade-grown coffee because it creates important winter habitat for migratory songbirds, and participate in citizen-science projects such as Christmas Bird Count, Great Backyard Bird Count, National Migratory Bird Count and Project FeederWatch, to increase our knowledge of bird populations. We should also support the purchase of public lands and defend those we already have from bad land management practices, for instance, our national and state forests, gamelands, and the 95 million acres of land and water managed by the U.S. Fish and Wildlife Service. In other words, the more wild lands we have, the better for the birds.
Finally, three species appear on the Audubon list with a 0–Eskimo curlews, Bachman’s warblers, and ivory-billed woodpeckers. Last April, as my husband and I sat in a cabin at Raccoon Creek State Park eating breakfast, we heard on our radio the most exciting news for birders in decades–at least one ivory-billed woodpecker still lives in a most unexpected place –the Cache River National Wildlife Refuge in northeastern Arkansas. And it was discovered not by a scientist, but by a kayaker–Gene Sparling–who had posted his finding on his website.
Tim Gallagher, editor-in-chief of the Cornell Laboratory of Ornithology’s Living Bird, saw the posting while researching a book he was writing on ivory-billed sightings over the years. On February 27, 2004 Gallagher, veteran birder Bobby Harrison, and Sparling headed into the Cache River NWR, part of a vast, 500,000 acre bottomland forest of old growth and younger trees that also includes the White River National Wildlife Refuge. Paddling canoes into the area under Sparling’s leadership, Gallagher suddenly spotted a large black and white bird that flew across in front of them at close range and in good light, a mere 68 feet away. There was no doubt that it was a ivory-billed woodpecker.
Such a discovery is a “spectacular ray of hope,” Cornell lab’s director John Fitzpatrick said. Since then there have been six more sightings of a male ivory-billed in that area and the hope is that at least a small breeding population of ivory-bills lives in the depths of what is still an almost impenetrable wilderness–wilderness owned mostly by the national government and by private landowners who have kept it wild.
Surely such a fantastic discovery should embolden all of us to re-examine our own priorities and try to do as much as we can to ensure that in another 40 years bird numbers will have zoomed back to at least 1966 levels.
“My dream is that my great, great-grandchildren will be able to see a place like the virgin cypress forests we once cut down–and with the ivory-billed flying through it,” Gallagher said.
My dream is that the United States will be such an incredible haven for large populations of woodland, shrubland, grassland, and wetland birds, that we will no longer need Audubon reports when my great-great-grandchildren are alive.
Leave a Reply