Human Hazards are Major Causes of Wildlife Injuries Treated at The Wildlife Center
The Wildlife Center’s data indicates that the most common causes of injury to wildlife presented for rehabilitation in the Metropolitan Birmingham area are collision with automobiles, collision with plate glass windows, and cat attack. The Wildlife Center’s mission is to alert the public to preventable problems affecting our wild neighbors, in the hope that knowledge may lead to increased awareness and concern. Here is a breakdown of common problems seen at The Wildlife Center.*
Auto Collision
The Wildlife Center treated 92 raptors of 11 species for injuries received from collision with an automobile in 2002. Barred Owls, Red-tailed Hawks, and Screech Owls were the species most affected, followed by Broad-winged Hawks, Red-shouldered Hawks, and Cooper’s Hawks. The Center treated 36 songbirds of 25 species that had been hit by cars. Species most often affected included Brown Thrashers, Mourning Doves, Cedar Waxwings, and Northern Cardinals. Slow-moving animals like box turtles and opossums are especially prone to injury. The Center received 18 turtles that had been hit by a car, with Box Turtles leading the list and 41 mammals that were hit by a car, with Eastern Grey Squirrels leading the list.
Highways
are especially lethal because they attract so many wildlife species, some of
which have not developed the ability to recognize the threat of a distant object
moving at speeds in excess of a mile a minute. Highways are actually a new kind
of wildlife habitat. The roadside ecosystem combines several types of habitat
in close proximity, from tall trees and dense shrubs, to moist, grassy roadside
ditches. Many wild creatures are forced to cross in the face of fast-moving
traffic where roads bisect their territories. Cold-blooded reptiles and
amphibians are attracted to blacktop roads at night, when air
temperatures drop
and the heat-absorbing asphalt retains its warmth. Owls have learned to patrol
the roadsides hunting for cold-blooded prey, as well as small mammals concealed
in roadside ditches. Hawks take up the patrol during daylight hours, searching
for the same prey species. Carrion-eaters, from crows and vultures to raccoons,
opossums and other mid-sized animals, are on the look-out for a free meal
wherever a wildlife casualty lies flattened on the pavement. Intent on their
meal, they too may end as roadkill.
Window Strikes
The Wildlife Center documented 47 birds of 34 species that were injured by collision with glass windows in 2002. Leading the list was the Ruby-throated Hummingbird, followed by Cedar Waxwing, Northern Cardinal, Carolina Wren, and Sharp-shinned Hawk. Birds are unable to perceive glass as a barrier, and are injured or killed outright where flight paths are close to unshielded windows.
Cat Attack
The Wildlife Center’s leading cause of injury to both juvenile and adult birds, as well as small mammals, is attack by domestic cats. Reliable estimates indicate that free-ranging house cats kill four million songbirds a day in the continental United States. Locally, the Wildlife Center treated 75 adult birds of 25 species following cat attacks, as well as 128 baby birds of 20 species, for a total of 203 documented cases of cat attack. The species of juvenile birds most affected are not the same as the adult species most often attacked. Carolina Wrens, American Robins, and Brown Thrashers led the list of juveniles most often attacked. Among adults of those same species, only the Brown Thrasher was among the six most commonly attacked species, after Mourning Dove, Northern Cardinal, House Finch, Bluebird, and Ruby-throated Hummingbird. Cat attack victims usually suffer from a combination of internal injuries caused by crushing and small deep puncture wounds. Because these injuries are usually concealed by a bird’s feathers, they are often reported as “minor”. However, cat bites contain as many as 50 types of infectious bacteria, and usually result in serious infections, for which treatment is often difficult. Nationally, it is estimated that no more than 20% of birds attacked by cats survive the injuries. Cat attack was also the leading cause of injury for adult mammals treated in 2002, closely followed by dog attack. The death of the mother was the leading cause of orphaning among infant mammals received by the Wildlife Center. Although it was not possible to determine the cause of death, the likelihood is that causes were similar to other adult mammals received by the Center. 584 of the 781 mammals treated by the Center in 2002 were orphans. Other major causes of problems for infant mammals were destruction of the nest or den tree (14%), cat attack (14%), and dog attack (8%).
*Figures presented are only a percentage of all cases received, since the cause of injury cannot always be determined.