Disappearing Common Birds Send Environmental Wake-Up Call

6/14/07

Population declines for some of the most recognized and beloved birds in Pennsylvania echo the disturbing findings of a new analysis by the National Audubon Society that reveals how local and national threats are combining to take a toll on birds, habitat, and the environment across the country.

“These are not rare or exotic birds we’re talking about—these are the birds that visit our feeders and congregate at nearby lakes and seashores and yet they are disappearing day by day,” says Audubon Chairperson and former EPA Administrator, Carol Browner. “Their decline tells us we have serious work to do, from protecting local habitats to addressing the huge threats from global warming.”

The national study found that continental populations of some common birds nosedived over the past forty years, with several down nearly 80%. In Pennsylvania, the golden-winged warbler, the eastern meadowlark, and the wood thrush top the state list, with declines between 62 and 98 percent. Golden-winged warbler and wood thrush populations elsewhere in the country have not experienced such dramatic declines. However, Pennsylvania’ fragmented and overbrowsed forests provide nesting habitat for approximately 8.5 percent of the world’s wood thrushes and nearly 9 percent of the golden-winged warblers. The eastern meadowlark has experienced a 72 percent decline nationwide compared with an 86 percent decline in Pennsylvania, largely due to the widespread loss of the state’s family farms, which provided large open tracts of field space. The pronounced national declines are attributed to the loss of grasslands, healthy forests and wetlands, and other critical habitats from multiple environmental threats such as suburban sprawl. The study notes that these threats are now compounded by new and broader problems including the escalating effects of global warming and demand for corn-based ethanol.

“Here in Pennsylvania, the biggest culprits are habitat fragmentation, a white-tailed deer herd out of balance with the rest of the ecosystem, and suburban development,” says Dr. Timothy Schaeffer, Executive Director of Audubon Pennsylvania. “Fragmented forests become susceptible to non-native pests and diseases, making them unsuitable for wood thrushes. Deer overbrowsing hinders forest regeneration and results in poor cover for ground- and understory-nesting birds. This lack of early successional woodland affects ruffed grouse and golden-winged warblers. Meanwhile, grassland birds like eastern meadowlarks are declining due to development of farmland and changing agricultural practices. Finally, while Audubon supports well-sited wind power, we are unsure of the potential impact that wind turbine sites along our prominent forested ridges will have on the millions of migratory birds that use those ridges as flyways.”

Considering these multiple factors, the five species especially hard hit in Pennsylvania include:

• Golden-Winged Warbler is suffering from loss of suitable successional habitat, dense shrubs and young saplings, due to reforestation and development. The species, down 98 percent in Pennsylvania, also faces competition from the closely-related blue-winged warbler, which is expanding its range to the north.
• Eastern Meadowlarks, down 86 percent across the state, are threatened by the loss of farmland and changing agricultural practices. Further, the potential conversion of acres currently protected for conservation to biofuel crops like corn puts both eastern and western meadowlarks at even greater risk.
• Wood Thrushes rely on large interior forests and are threatened by habitat fragmentation, deforestation and nest parasitism. Each year wood thrushes, down 62 percent in Pennsylvania, migrate from Central America to the U.S., where Pennsylvania houses 8.5 percent of the world’s breeding population.
• American Bittern populations nationwide are declining significantly, 59 percent in the last 40 years. The main threats faced by the species are degradation of wetland habitat from invasive plants and diminished water quality, as well as development. This species uses Pennsylvania’s wetlands as stopovers during migration while a small number continue to reside here throughout the breeding season.
• Ruffed Grouse, down 22 percent statewide, are found in young open mixed deciduous-coniferous forests. Pennsylvania’s official state bird, the ruffed grouse is dependent on successional habitat. Loss of forests to development and the loss of old fields as forests mature are key threats, while overbrowsing by deer makes some early successional forest less suitable for the species.

Pennsylvanians care deeply about birds and their habitat, and Audubon Pennsylvania is working with individuals and organizations across the state to monitor bird populations and promote sound stewardship on the ground. With the majority of land in Pennsylvania in private ownership, Audubon Pennsylvania is hard at work engaging landowners with advice and assistance for creating bird-friendly environments on their properties. “Our Audubon At Home program is offering private citizens, educational facilities, and business campuses the tools to better manage their land as bird habitat,” says Schaeffer. “Also, Pennsylvania was the first state in the nation to designate Important Bird Areas (IBAs). Today, Pennsylvania boasts 84 Important Bird Areas, and our staff — with the help of local Audubon chapters, private landowners, and partnering organizations — is implementing conservation plans that will help protect and restore critical bird habitats within these IBAs.”

Audubon’s State of the Birds: Common Birds in Decline list stems from the first-ever analysis combining annual sighting data from Audubon’s century-old Christmas Bird Count program with results of the annual Breeding Bird Survey conducted by the U.S. Geological Survey. “This is a powerful example of how tens of thousands of volunteer birders, pooling their observations, can make an enormous difference for the creatures they care the most about,” says noted natural history writer and Pennsylvania resident Scott Weidensaul. “Thanks to their efforts, we have the information. Now all of us — from birders to policy makers — need to take action to keep these species from declining even further.”

Public response will shape the long-term outlook for Pennsylvania’s Common Birds in Decline. “Fortunately, individuals can still make a difference,” says Schaeffer. “I encourage people to visit our web site or contact their local Audubon chapter to find out what they can do to help. Audubon Pennsylvania offers a wealth of resources for conserving our natural world. Healthy bird populations are the result of a healthy environment, and a healthy environment improves the quality of life for all Pennsylvanians.”

Click here to view the Pennsylvania fact sheet.

More information about Audubon’s Common Birds in Decline analysis is available at www.audubon.org. In addition, journalists may visit Audubon’s online CBID Press Room.