Insects, invertebrates, birds, butterflies and animals don’t eat non-native plants unless they have nothing else to eat. The chemicals, fats and nutrients don’t taste good to them and don’t provide the levels of fats and proteins they need to sustain themselves. According to Doug Tallamy in his book Bringing Nature Home, native plants have 29 times the biodiversity of non-native plants. Without our native insects, invertebrates, birds, plants and animals, our natural systems, such as infiltration of rainwater, pollination, nutrient and chemical management, flood protection and wildlife habitat don’t function. As a result, municipalities are forced to raise taxes to replace these services. Before we know it we will have lost the trees and the natural community that brought us here in the first place.
Within the interrelated web of Pennsylvania's wild resources, obscure species are the foundation on which well-known, charismatic species rely: meadow voles feed birds of prey and furbearers; countless terrestrial insects support wild turkeys, grouse, pheasants and songbirds; aquatic insects form the mainstay diet of trout populations; and diverse native plant communities support a host of herbivores, from chipmunks to elk. Across Pennsylvania, the survival of game birds and mammals, sport fish and "showy " wildlife which collectively support a $5.8 billion annual recreation industry—depends on the continued well-being of some of our most obscure, least understood species.
Bird watching is the fastest-growing outdoor activity and in Pennsylvania, people spend more on wildlife watching than on either fishing or hunting. In 2006, Pennsylvanians spent $2.1 billion on wildlife watching alone. Many more people enjoy the outdoors while walking, biking, kayaking, watching butterflies and gardening in their own backyards. When William Penn first encountered the forest, there were approximately 2100 species of native plants. Unfortunately, habitat changes that have occurred since the settlement of Pennsylvania have taken their toll on the Commonwealth's fish and wildlife. During the past 300 years, 156 plant and animal species have disappeared from Pennsylvania, and another 351 species have become threatened or endangered. Thus, 507 species (13% of Pennsylvania's plants and animals) are threatened, endangered, extirpated, or extinct. Although Pennsylvania still enjoys a rich diversity of fish and wildlife, many species have already been lost and many more are in jeopardy.
By the time Theodore Roosevelt brought attention to our natural heritage in 1900, more than 1300 non-native plant species had been introduced, accounting for 37% of all plant species. The Department of Conservation and Natural Resources estimates that nearly 25% of current native plant species are functionally extinct. The base of our food web is seriously shrinking.
Because fish and wildlife are so valuable to humans in so many ways, declines in numerous populations are a reason for concern. Some wildlife, such as the northern bobwhite quail, have declined so rapidly that they are in danger of disappearing entirely. These "immediate concern" species require immediate conservation action. Others, including the wood thrush, remain widespread but deserve attention to prevent continued decreases. The sobering state of the Commonwealth today is that most fish and wildlife species currently enjoying population increases are exotic invaders from other countries or species that are undergoing population explosions due to a lack of predators or other population control mechanisms.
The two biggest threats to biodiversity in Pennsylvania are the destruction and fragmentation of wildlife habitats through development and the introduction of invasive, non-native species. An out-of-balance white-tailed deer herd is the third major threat in some areas.
In the natural web, everything is connected to everything else. An impact on one part disrupts another. While there are many levels of tolerance, the better the balance the more sustainable the system.
Because bird, fish and other wildlife habitats are directly affected by human use of the land, the health of Pennsylvania's fish and wildlife is in our hands. While endangered species don’t usually visit your backyard, we have a stewardship responsibility for maintaining healthy populations of still-common species in addition to preventing extinctions. Although our understanding of the wild systems of Pennsylvania is greater now than it ever has been, no one knows what a continued loss of species would mean for the Commonwealth's natural web of life.
You’ve probably heard about the practice of coal miners using canaries to ensure their safety against the cumulative build-up of toxic fumes. Ecosystems can use birds to monitor their health. Like a canary in a coal mine, birds are a good indicator of a healthy system because:
- Birds are mobile and responsive to environmental change
- Bird populations tend to indicate a set of environmental factors
- Birds are taxonomically well-known and stable
- Bird populations and diversity are well-monitored
Most important for our neighborhoods, birds can be present only if insects and berries from native plants and animals are providing them the types of food they need to be successful in their journeys north and south or for those who like it here year-round. If plants are healthy, then the natural cycles are in balance and the system is probably functioning in high-performance mode.
As Douglas Tallamy points out in his book Bringing Nature Home, we have lost most of our native species habitat. Over the last 300 years of colonial settlement in the United States we have clear-cut the trees, scraped the ground and introduced more than 3400 alien plants, which have invaded over 100 million acres of the country. That area is expected to double in the next 5 years.
A national study performed by Audubon found that continental populations of some common birds have nosedived over the past 40 years, with several down nearly 80%. In Pennsylvania, the golden-winged warbler, eastern meadowlark and wood thrush top the state list, with population declines between 62% and 98%.
Golden-winged warbler and wood thrush populations elsewhere in the country have not experienced such dramatic declines. However, Pennsylvania’s fragmented and over-browsed forests provide nesting habitat for approximately 8.5% of the world’s wood thrushes and nearly 9 percent of the golden-winged warblers. The eastern meadowlark has experienced a 72% decline nationwide compared with an 86% decline in Pennsylvania, largely because of the widespread loss of the Commonwealth’s family farms, which provided large open tracts of field space. The pronounced national declines are attributed to the loss of grasslands, healthy forests, wetlands and other critical habitats from multiple environmental threats, such as suburban sprawl and air and water pollution. The Audubon 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.
An increase in native plants will help to increase bird species diversity and ecosystem health. Every time we lose woodland or a meadow or force a species to extinction, we are encouraging our own demise. While implementing the best landscaping practices on an individual property can help support wildlife and protect natural resources, linking adjacent properties through a broader community plan can yield even greater conservation outcomes. For more information on Bounty go to Chapter 5 and Appendices 3 through 14.