Pollution

Pollution increases in sprawling areas. More significantly in terms of wildlife and biodiversity, sprawl expands the effects of pollution into areas where environmental quality may not yet have been severely compromised. Industrial and transportation sources release synthetic substances and chemicals into the air, water, and soil that are toxic to many species and degrade habitat. In addition, light and noise associated with developed areas can have negative effects on wildlife behavior and natural cycles.

Water and Soil Pollution


Toxic chemicals, such as mercury, dioxin, and PCBs can have devastating effects on wildlife when they are released into the soil and water. An animal's endocrine system can be disrupted, causing reproductive problems and deformed offspring; an animal's immune system can be compromised, allowing a higher susceptibility to disease and infection; and if the concentration of toxins reaches a high enough level, an animal can die. Wildlife can be exposed to pollutants through skin absorption, the animals or plants they eat, and the water they drink. Amphibians and aquatic species are especially vulnerable to pollutants in streams, rivers, and lakes.

Air Pollution


As sprawl continues to extend the boundaries of urbanized areas, people become more car-dependent and travel greater distances, spewing more vehicular emissions into the atmosphere. Vehicular and industrial emissions in urbanized areas are the main sources of air pollutants, such as nitrogen oxides and sulfur dioxide. Plants or wildlife (especially species with thin, moist skin, such as amphibians) can inhale or absorb these pollutants, causing health problems, such as cardiac and respiratory dysfunction. Air pollution also contaminates water and soil through acid rain. Sulfur dioxide, a main component of acid rain, can damage plant communities by impairing photosynthesis processes. Plants weakened by acid rain may become vulnerable to root rot, insect damage, and disease, causing serious damage to plant communities and forest ecosystems.

Noise Pollution


Noise in urban areas from sources such as automobiles, airplanes, and heavy machinery, can affect wildlife behavior and physiology in many ways. Behavior responses can range from head-raising and minor body movement to escape and panic behavior, such as stampeding (National Park Service 1994). Noise also can cause chronic stress, increased heart rates, metabolism and hormone imbalance, and nervous system stimulation (Fletcher 1980, 1990). These responses may cause energy loss, food intake reduction, an avoidance and abandonment of habitat, and even injury or death (National Park Service 1994). For example, caribou calves experienced a higher mortality rate when exposed to airplane noise (Harrington and Veitch 1992). Also, noise sometimes flushes birds from nests, occasionally causing broken eggs, injured young, or exposure to predators (Bunnell et al. 1981, Gladwin 1987). Finally, bird songs and calls that are used to mate and establish territories may be disrupted by excessive human generated noise. View Noise Effects on Wildlife Fact Sheet from the Noise Pollution Clearinghouse website.

Light Pollution


Developed areas produce artificial light that causes problems for wildlife. In coastal areas where sea turtles nest, hatchlings use the light from the moon and stars to guide their way to the ocean. Often bright artificial lights from urban areas draw the hatchlings inland, resulting in mass mortalities.

Some ornithologists are studying the issue of migratory birds flying into tall buildings and towers due to light attraction. The Fatal Light Awareness Program has documented the fatalities of millions of birds from such collisions. Streetlights, neon signs, and late night golf driving ranges may potentially keep wildlife from moving, nesting or foraging near urban areas. However, more study is needed to determine how urban light impacts wildlife. For more information, go to the International Dark-Sky Association website.

Threats to Wildlife
More than one-third of wildlife species in the United States are considered in danger of extinction. The main threat to wildlife is habitat loss and fragmentation.
Invasive Species
Sprawl encourages the growth and expansion of invasive exotic species.
Impervious Surfaces
Sprawl increases the amount of impervious surfaces such as roads, parking lots, sidewalks, and rooftops.
Natural Cycle Disruption
The paving over of wetlands, grasslands, forests and other sensitive areas have resulted in many poorly functioning ecosystems.
Pollution
Sprawl extends pollution into areas where environmental quality may not yet have been severely compromised.