Birds of prey may seem invulnerable since they are superb hunters and powerful apex predators, but in reality their are many risks to raptors that threaten their populations. HawkWatch International works to study and mitigate threats to protect raptors and their habitats. Browse our work to read about some of the projects we are involved in.
Threats to raptors come primarily from humans. While all animals are subject to natural threats such as disease and predation, raptors suffer far greater harm from human causes, including:
The loss of native habitat is the single greatest threat to raptor populations. In the last several hundred years, the North American landscape has changed greatly as a result of human development. As the landscape and habitat change, suitable raptor (and wildlife in general) habitat decreases. For example, The Spotted Owl lives in old growth and late succession areas in Pacific Northwest forests. In the lower 48 United States, it is estimated that only 5% of the original old growth forest remains. In order to ensure the survival of the Spotted Owl, which has declined drastically due to habitat loss as a result of logging, old growth forest areas need to be protected.
Habitat degradation (change in make-up or structure of a landscape) is also a serious threat to raptors. An example of degradation is the change in plant species from native to non-native throughout the sage/grassland deserts of the western U.S. One introduced species in particular as a result of cattle grazing is a big threat to the Western sage/grasslands, Cheatgrass (Bromus tectorum), and has taken over the plains replacing much of the native grasses and affecting native plant life in general. As a result, small mammals that feed on native grass seeds are declining in the Western sage/grasslands, thus predators such as the Prairie Falcon, which prey on these small mammals, have a more difficult time surviving.
The science is clear: Human activity is causing our climate to change. And as temperatures rise and climate patterns are altered, we can expect to see excelerated changes to wild landscapes. These changes will severely impact the crucial habitats wildlife need to survivle. For raptors, this will manifest in shifts to the ranges of particular species, changes in migration (migrating less, not as far south, or at different times), changes to prey base, increased competition for territories and cavities or nests, etc. Climate change will also compound exisiting threats such as the spread of invasive species and increased competition. More research is needed to understand the full magnituted of climate change on raptors. This is a serious issue we must face as a nation and as a world.
Lead poisoning is one of the most common types of poisoning that raptors suffer, and this type of poisoning occurs mostly indirectly. Lead is typically ingested when swallowed in the process of feeding on prey that contains lead. This is often in the form of a lead sinker (used by fisherman) that is swallowed by a fish, and the fish is thus preyed upon or eaten by a raptor such as an Osprey or Bald Eagle. Also hunters use lead ammunition when deer or waterfowl hunting. As raptors feed on waterfowl or scavenge on waterfowl or deer carcasses that contain lead, they ingest the lead and become sick; this is also an issue for mammals that feed on carcasses. Poison is also put out intentionally by land owners with the intent to kill raptors or ravens they perceive as vermin or nuisances. This is of course illegal, but difficult to enforce or become informed about when occurring on private property.
Raptors are susceptible to colliding with several man-made objects; the most common types of collisions are listed below:
- Vehicle Collisions - Raptors often hunt along roads and highways, looking for mammalian prey hidden in the grassy strips of open space on the sides of roads or within the median. As raptors swoop down with intense focus (tunnel-vision) on prey they sometimes cross low over a road and are struck by a car. Sometimes they successfully capture prey and fly off with it only to be struck returning to their perch (especially if the prey is heavy and prevents them from gaining altitude). Vehicle collisions are common in rural, open areas with large concentrations of raptors near high-speed limit roads.
- Wind turbines – Wind-powered turbines are often placed on the side of mountain ridges or hillsides to maximize the use of updrafts (wind forced upward as it strikes the side of a hill or ridge) that turn the blades of the turbine. Raptors also use updrafts to soar along north-south mountain ranges during migration or in winter when searching for prey. When doing so, they may misjudge the speed of the turbines or lose focus of their surroundings while stooping for prey, and be struck by the blades.
- Powerlines/ high tension wires – Since powerlines or wires in general are narrow and may be difficult for a bird to see, especially in a rain or snowstorm, raptors sometimes fly into them. Birds that are sick are more susceptible to flying into powerlines than healthy ones.
- Windows – While uncommon, some raptors do fly into windows while chasing prey (birds) if the prey flies near or into a window; or simply because they do not see a window but rather see a perch or tree branch that is reflected in the window.
- Trains - Raptors also collide with trains when hunting along railroad tracks in the same way they collide with automobiles. It is rare for a raptor to be struck by a train as the probability is low due to the limited number of operating trains.
- Airplanes – Airport runways are often surrounded by expanses of open grassland, which attracts open-country raptors. At times, planes taking off or landing collide with raptors that are flying across a runway, or collide with a group of birds in their flight path. Birds may become sucked into an engine and cause a plane to abort a flight.
- Barbed wire – Raptors sometimes land on a fence lined with barbed wire and a wing or foot becomes entangled, trapping the bird there indefinitely. They may also become entangled chasing prey near a fence or attempting to snatch a bird from atop a fence.
Raptors often perch on utility poles since they offer a resting spot and vantage point to spot prey. Some species (because of their large wingspans - up to 7’ for eagles) are more susceptible to electrocution as they land or take off from poles. Electrocutions most often occur when a bird completes a circuit by spanning (wrist to wrist) two energized parts of equipment on a utility structure that has a high electrocution risk as opposed to structures that are deemed “raptor-safe.” Electrocution risk is highest in areas with original structures that lack retrofitting efforts.
Persecution of Raptors
The trapping or shooting of raptors is still prevalent in some areas of North America. According to the Migratory Bird Treaty Act (Title 50, Parts 10, 13, 14, 17, 21 and 22) it is unlawful to kill, capture, collect, possess, harass, buy, sell, trade, ship, import, or export any migratory bird, including their feathers, eggs, and all other parts. Contained within the definition of ‘harassment’ includes disturbance caused by visiting nests or ‘bumping’ birds for photography. Permits to possess a bird or bird parts are granted by the U.S. Fish and Wildlife Service and state agencies in which the permitee resides, but only for research, rehabilitation, education, religious purposes, and falconry. Other laws that protect raptors are the Eagle Protection Act, the Endangered Species Act, and other local laws.
While it may seem extreme, it is illegal to possess even a single feather of a protected species. Without this extension of the law it would be easy for a poacher to claim they had found a feather, when they had actually shot a raptor to obtain the feather.
There are several diseases or illnesses that threaten raptors, including the more well-known bird related diseases such as West Nile Virus and Avian Influenza. West Nile Virus is prevalent in birds as well as humans. It is caused by mosquito bites; however, most raptors acquire the virus by preying on or scavenging birds infected with the virus, thus becoming sick themselves. The virus is not deadly to humans, but is highly deadly to birds. Please report any sick raptor you see or dead raptor you find to the appropriate state authorities.
Avian Flu is a virus that is highly infectious and most prevalent in domestic fowl, but is present and spread between wild birds such as gulls, shorebirds, and especially waterfowl. Raptors are less susceptible to Avian Flu, but can contract it if they come in contact with an infected bird. The virus can be and often is deadly to birds. Signs that a bird is infected with West Nile Virus or Avian Influenza are lethargy, weakness, inability to fly or hold its head up or stand (lack of balance).
Birds that are either raised by people or cared for by people at an early stage in their development may become “imprinted.” This means that they see people instead of their own species as their parents, or see themselves as human, and have difficulty associating with birds. Most times imprinted birds have lost their natural instincts and are too tame to be released into the wild population. Imprinting is not a common issue, but does occur when people raise baby birds that are abandoned or thought to be abandoned. In raptors, imprinting is especially common and is the norm in falconry. If a bird associates its owner as its own kind or as its parent (by providing food), this helps create a trust or bond between bird and falconer. This bond keeps the bird from flying away when it is free-flying on hunts. There are times when a falconry bird does fly away or get lost, and sometimes the owner is never tracked down. On these rare occasions, these imprinted birds are often found a home at an education facility where they reside as representative ambassadors to raptors.
What To Do If You Find an Injured Raptor
In general a raptor will not let a human approach it while on the ground unless it is injured or guarding a kill. If you find an injured raptor it is important to keep your distance from the bird. Raptors have extremely sharp talons and powerful feet (a Red-tailed Hawk can squeeze its foot with 160 lbs. of pressure compared to a person who can squeeze their hand with 35-40 lbs. of pressure), and so they can do quite a bit of damage. For more detailed information about dealing with injured wildlife, click here.