Other Impacts

Birds face a wide variety of threats and need our help

In addition to habitat loss and climate change, Bay Area birds face numerous other issues and threats. These include pollution and pesticides; fire and controlled burning regimes; invasive species; collisions; entanglement and entrapment; predation; disease; and illegal trade in wildlife. Understanding these threats to birds can lead to effective solutions, and increased appreciation for birds can lead to action.

Our avian research and habitat restoration programs focus directly on some of these issues. Our Avian Disease Prevention Program curbs the spread of avian diseases; our Snowy Plover program helps reduce predation by gulls and corvids; and our tidal marsh restoration program reduces the impact of invasive species. We also partner with agencies and organizations such as the Oiled Wildlife Care Network, U.S. Fish and Wildlife Service, and the Audubon Society, that tackle bird threats such as pollution, collisions, and other threats. Most importantly, our outreach programs inspire generations of Bay Area residents to support bird conservation.

Pollution/Pesticides
Fire
Invasive Species
Collisions

At least five billion pounds of pesticides are manufactured globally each year and 20 percent is used in the U.S. and Europe. These poisons damage bird populations from concentrated doses; bioaccumulation (where pesticide levels become more concentrated with each step in the food chain); hormonal effects; and fewer or weaker eggs. Pesticides also destroy prey and damage plants that birds depend on. Rodenticides are also an issue, especially for raptor species. Birds are also impacted by air pollution and water pollution, including oil spills.

Wildfires, like the ones we experienced in the North Bay and throughout the state and country in 2017, can impact bird populations. Sometimes fires, such as prescribed burns, can help birds by increasing grassland habitat. But for other species such as the Greater Sage-grouse, firs can allow invasive species to take hold and crowd out the native plants birds rely on. They also destroy habitat and pollute air and water.

Invasive plant species can replace the native plants birds need for food, shelter, and nesting; may cause declines in the insects bird species depend on; and can even be toxic. Invasive insects like red fire ants can also be dangerous to ground-nesting birds, and invasive species such as the red fox can put intense pressure on native bird survival. Invasive birds can displace native birds in dwindling nesting habitat, and can bring parasites and exotic diseases such as the West Nile virus.

An increase in human development means an increase in the number of barriers and obstructions in areas where birds fly, leading to more and more bird collisions with man-made structures. Recent studies estimate there are about 2.8 billion bird collisions annually in the U.S. Some of the factors that contribute to collisions include infrastructure height, reflective windows, lighting, weather, location, and bird vision and health. Birds also collide with other human designed objects such as cars and energy infrastructure.

Entanglement/Entrapment
Predation
Disease
Illegal Trade in Wildlife

Many sources contribute to entrapment of birds, including oil, tar, and brine pits; evaporation ponds; tanks, tubs, and other open containers; oil spills; garbage (such as soda can plastic rings), and fishing nets. After becoming trapped, birds drown, starve, experience cold and heat stress, or asphyxiate. The also die while trapped from ingesting toxins, becoming sick, or being eaten by predators.

Like most wild species, birds are impacted by predators. In nature, the relationship between prey and predator can usually find a balance. But urban environments like the Bay Area can create an imbalance that threatens certain bird species. For instance, many gull and corvid species like to eat human food and garbage readily available in urban environments, which helps their populations grow. They also like to eat Snowy Plovers, Least Terns, and other sensitive species. This puts these more sensitive species at greater risk.

Diseases such as avian botulism, avian influenza, avian cholera, and West Nile virus have affected North American migratory birds for many decades. This is because, while healthy bird populations are resistant to infectious diseases, when bird populations are stressed by all of the impacts mentioned above they become more vulnerable to disease.

Wildlife trafficking is thought to be the third most profitable illicit trade in the world after drugs and weapons, worth an estimated $10 billion a year, and birds are the most common contraband. The U.S. State Department estimates that two million to five million wild birds are traded illegally worldwide every year. Individual birds are damaged when taken from their native habitat; they can spread diseases and parasites; and their loss is felt in the bird populations left behind.

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