Fences, windows and pipes are all part of a normal human landscape, but they also can pose significant, yet largely unknown, hazards to wildlife. As we try to live side by side with nature, in a way that benefits people and wildlife, there are things that we can do to reduce the impact of our anthropogenic infrastructure on wildlife.
Studies show that fences that do not meet certain criteria are hazardous to wildlife, causing unnecessary mortality among adult, juvenile and young wildlife. Deer, elk, and moose must frequently jump over fences to move throughout a landscape, but smooth or barbed wire fences that are too high or with wires spaces too close together can snag or tangle their legs. Hazardous fences are especially problematic for juveniles, who may be too small to jump over a tall fence, but too large to crawl under it. Some fences are a complete barrier to fawns and calves. They may become separated from their mothers, and may perish from exposure, starvation, or predators.
Birds can also collide with fences, break their wings, impale themselves on barbs, and become tangled in wires. Large, low-flying birds such as ducks, geese, grouse, hawks, and owls are most vulnerable. Waterfowl may fly into fences near or across waterways, and hawks and owls may careen into fences when swooping in on prey. Fencing that crosses water sources are problematic for bats that drink on-the-fly, posing a hazard as they access the water.
The hazards to wildlife from open vertical pipes, and posts are largely unknown to the public. Birds are especially vulnerable in their fledgling stage, when they are just learning to fly. Their wings are unsteady and they often fall—and if they fall into a tall pipe, there is no escape. They aren’t able to open their wings or get enough lift to fly out, and die from dehydration and starvation. Many residential and industrial sites have open pipes or posts such as in gate and fence posts, irrigation systems, or other pipe structures.
Private residences and buildings all have a variety of vents. Improperly covered dryer or stove vents are a popular spot for sparrows to nest. The sparrows collect nesting materials to line their nest, including dry grasses, twigs, dryer lint, and even litter; these create a fire hazard in your vent. And once the nestlings hatch, there is also a risk of them sliding down inside the vent and becoming trapped.
Fledglings, baby hares, and even frogs can also get trapped in your window wells. A small sparrow fledgling who is learning to fly, may not be able to fly back out of a deep window well, after landing inside. Similarly, a hopping creature looking for a quick escape may end up in a window well and not be able to climb back out. If not found and set free, the animal will eventually die of starvation.
Rain barrels or buckets can also pose a serious danger. Many smaller wildlife such as birds, squirrels and even salamanders may see these as a source of water, and accidentally fall in with no way out. Even buckets left upright outdoors can unintentionally pose a drowning hazard to wildlife, after filling with rain water.
Collisions with windows kill an estimated one billion birds each year worldwide. During the day, birds see through windows, not realizing there is an obstruction, or they may see the reflections of trees or sky and think that there is nothing in their way. At night, nocturnal migrating birds are lured by lights left on in high-rises and other buildings. They follow their instincts to use the moon and stars to navigate at night, but can become confused by artificial lights in human environments, especially on foggy or cloudy nights.
Predation by cats is the leading cause of songbird deaths, with over 100 million deaths estimated annually in Canada alone, and some estimates place this number much higher, closer to 200 million.
The best way to keep your cat and wild birds safe is to keep your cat indoors. This is especially important during migration and breeding seasons to prevent them from killing birds. Indoor cats live longer, healthier lives than outdoor cats. If you let your cat outside, consider keeping them on a leash or harness, or keeping them in an outdoor enclosure.
Find out more about how to keep cats and birds safe, or take Nature Canada's pledge to prevent your cat from roaming freely outdoors.
This project was made possible with funding from