November 03, 2016
By Curator of Birds Michael Macek and Vice President Architecture & Planning David McGuire
The fall migration is a great time to see many birds that normally aren’t found in our region because, depending on a species' individual route, birds may pause between breeding and wintering ranges. This allows us to see them as they fly through.
Often, however, these birds are killed before they make it to their winter homes. The American Bird Conservancy reports that hundreds of millions of birds die in collisions with communication towers, power lines and vehicles.
Still, after habitat loss, the greatest threat to wild birds may be glass. Estimates show that up to 988 million birds are killed each year in the United States when they hit glass windows. Collisions have been documented for over 300 species.
Migratory birds and backyard birds are among the most common victims, including declining species like White-throated Sparrow, Hermit and Wood Thrush, Painted Bunting, Golden-winged Warbler, and Anna's and Ruby-throated Hummingbird.
At the Saint Louis Zoo, we use a lot of glass to provide natural light in our facilities. We also use glass viewing windows in animal habitats so visitors can see the animals in natural settings.
Unfortunately, birds cannot see glass and do not interpret windows as a barrier or a danger. Making matters worse, reflections of the sky and plant materials simulate a possible flight path that really does not exist.
Luckily, the Zoo’s Green Team of creative people began to work on practical solutions for making existing windows bird-safe. The Zoo also began exploring a host of strategies for new projects. Here are some of the tools we’ve used to create a bird-safe environment:
Here are some of the tools we’ve used to create a bird-safe environment:
- We have learned that using tape or even tempera paint stripes, when placed no more than two inches apart, if horizontal, and four inches apart, if vertical, works well to deter birds. We have learned that just placing a sticker on a window with an outline of a bird predator (a hawk, for example) isn't effective. A bird will just try to fly around the sticker—and possibly smack into the clear parts on either side of the decal.
- In contrast, the window tape simulates an obstacle for birds and breaks up reflections. There are even specially designed tapes on the market for this.
- The Zoo tested both vertical and horizontal tape applications on three of our buildings (the Zoo’s August A. Busch Jr. Administration Building, Cafe Kudu and the Orthwein Animal Nutrition Center). Thus far, we’ve had success: since the stripes were applied at Cafe Kudu in 2012, we’ve had no birds strikes.
For new construction, the Zoo has specified glass with permanently applied bird deterrent patterns. We tested this on the Tasmanian Devil Den in the Emerson Children’s Zoo, which opened in April 2016. This new home to two endangered Tasmanian devils includes two, eight-feet-high and eight-feet-wide Ornilux glass panels. This special glass is glazed with ultraviolet reflective webbing that is highly visible to birds, yet invisible to humans.
While for the average homeowner special glass may be too costly, there are inexpensive solutions. After six years of research and testing more than 150 products, the American Bird Conservancy has initiated a Glass Collisions Program that offers a comprehensive resource to help stop birds hitting windows. It lists proven products for existing and new windows for homeowners, architects, and builders, for every size and shape imaginable, and for every budget.
Why go to so much trouble to save birds? Because they contribute environmental benefits, including pollination, insect and rodent control, and seed dispersal. They also support the nation’s economy. A 2011 U.S. Fish and Wildlife Service survey shows that the nation’s 47 million birders, age 16 and older, bring in $31 billion in economic benefits in terms of jobs created by their travel and equipment purchases.
Birds are also great indicators of environmental health because they are so visible and are relatively easy to study.
Above all else, birds connect people with nature and add beauty, sound and color to our world. They provide countless opportunities for enjoyment and have cultural and spiritual importance to all of us.