Urban Threats to Migratory Birds |
Bird migration occurs every spring and fall and is one of the world's greatest natural phenomena. In spring, birds migrate north to their breeding grounds, and in the fall, after their babies have hatched and fledged, the adults and their young fly south to reach richer food sources and habitat for the winter.
In addition to the significant natural dangers of migration (such as bad weather, predators, lack of food), birds face many hazards in the urban environments they travel through.
The National Audubon Society says 100 million birds a year fall prey to cats. Dr. Stan Temple of the University of Wisconsin estimates that in Wisconsin alone, about 7 million birds a year are killed by cats. Cats killing songbirds is not "just part of nature." House cats were not a predator found in the world of North American birds until they were introduced by humans in the last several hundred years. Our migratory birds and their young are not adapted to survive the devastating effects of this introduced species.
What can be done to reduce cat-related injuries and death for birds?
- Keep house cats indoors at all times. Cats raised indoors exclusively will not "miss" being outside.
- Supervise any cat that is let outside until it is brought back inside. (Putting a bell on cats is not an effective way to warn birds of attack.)
- Spay or neuter all cats. Fewer cats means fewer songbird predators. Feral cat populations have devastating effects on birds.
Thousands of birds are injured or killed each year as the result of becoming tangled in a variety of man-made materials. If birds become entangled they are essentially trapped and cannot free themselves without assistance. They are prevented from flying, walking, feeding and avoiding predators Prolonged entanglement can cause permanent physical damage to skin, feathers, muscles, nerves or bones.
What to do if you find an entangled bird
Call a wildlife rehabilitation center such as Willowbrook Wildlife: 630 942 6200 or the CBCM hotline: 773 988 1867 for help and advice if you encounter a bird in an entanglement situation
(particularly if. it involves a bird that would be dangerous to safely handle - ex. herons, bitterns, cormorants, owls, hawks).
Critical step: hold the bird while you cut the material that is restraining it.
It may seem the most urgent thing to get the bird free from restraint but containing the bird is more important.
If you cut away only enough material to free the bird it may escape with hooks and string still attached to its body which will continue to harm and in many cases eventually cause the bird's death.
Do not just cut a bird free!!! Capture - then cut!
If a bird is small enough and reachable - wrap/cover its body in a towel, pillow case or net to contain it while you unwrap netting or cut string/line.
If the tangled bird is suspended out of reach - be ready to catch the bird if it falls after the restraining material is cut.
Do not allow a bird to drop into an area where it may sustain further injuries, get away, not be able to be reached or even drown if it falls into water still tangled!
Once you have contained the bird and cut away the entangled material - DO NOT LET THE BIRD GO!
It is likely that the bird has sustained an injury from the string, netting or hook and needs to be taken to a wildlife rehabilitation center for evaluation
The bird can be examined at the wildlife center to assess any damage - lacerations, infections, nerve or tissue damage that the entanglement may have caused.
Fishing line and its associated hooks and tackle that have been improperly disposed of along beaches, lakes and ponds is the leading cause of wildlife entanglement. Line and tackle left behind in branches and bushes become tangled on the legs, wings and beaks of birds.
Use proper disposal containers, cut disposed fishing line into small, safe pieces that will not become a risk to wildlife, spend some time cleaning up fishing line debris at a local pond, lake or beach, and support the use of biodegradable fishing line. More common use of a fishing line that did not have a prolonged life-span in the environment could reduce entanglement risks.
Kite or balloon strings caught in overhead branches or bushes can fatally trap a bird. Chicago Bird Collision Monitors rescued a mallard suspended upside down, for more than seven hours, 50 feet above the ground by kite string that had become tangled on its leg! When a kite becomes snagged in a tree, always remove as much of the string as can be safely reached. Be careful to never release balloons into the environment where the balloons and the string become hazards to wildlife.
Plastic six-pack rings for cans or plastic bottles or any other plastic ring from a container should always be cut apart before they are disposed of so there are no openings that could get stuck on the head or limb of an animal.
Soccer goal netting can trap nocturnal wildlife such as owls or cottontails that do not see the netted barrier as they run or fly through an open field at night. Animals and birds will be seriously injured or die as they struggle to free themselves once they become caught. If your park or school has soccer fields, please make sure the goal netting can be removed when not in use.
Holiday decorations can also be dangerous to wildlife. Birds become caught on loosely hung strings of outdoor holiday lights. The popular sticky, stringy spider webbing decorations placed across bushes at Halloween ensnare birds that live or feed in the vegetation. Birds will panic and injure themselves trying to escape or be trapped until they die in the webbing. Please make sure your holiday decorations are safe for wildlife.
Netted covers for trees intended to keep birds from reaching ripening fruit often snag the birds they are trying to exclude. If you use a cover for a fruit tree, it is important to frequently check for trapped birds.
Landscape netting used for turf reinforcement, plantings and erosion control can trap birds, small animals and the predators that pursue them. This ground cover can be particularly hazardous when placed where aquatic birds and their young exit the water to reach land. Areas that are netted should be frequently checked and should use degradable netting products that break down faster than standard plastic ground covers.
Automobiles / Trucks
Scientists estimate the number of birds killed by cars and trucks on the nation's highways to be 50 to 100 million a year. Those statistics were cited in reports published by the National Institute for Urban Wildlife and U.S. Fish and Wildlife Service.
What can be done to reduce automobile related injuries and death for birds?
- Always follow posted speed limits
- Slowdown or stop for birds crossing or foraging on roads
- Without putting yourself in danger, help birds crossing roads by moving them to the other side (without separating family members) and stopping immediate traffic dangers until birds are off roadway.
Cell tower lighting and designs can prove deadly to bird and bat populations. Tower lights may attract migrating birds. Invisible support wires can create collision hazards.
What can be done to reduce cell tower injuries and death for birds?
- Cell tower designs should be required to minimize harm to birds. Designs that do not rely on dangerous support wires are preferential. See bird-friendly tower construction guidelines from the USFW: (See com_tow_guidelines.pdf for more information.)
- Features that can create avoidance by birds should be incorporated into cell tower construction.
- Cell tower placement should avoid areas that are critical migratory routes.
- New technology: The lightRadio cube (See cube for more information) may eliminate the need for cell towers altogether.
Chicago Bird Collision Monitors (CBCM) is an all volunteer bird conservation project that operates under the auspices of the Chicago Audubon Society.
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