<em>By Wendy Lenhart and Christopher Waldron</em>
<em>Greater Philadelphia Chapter of AAZK, Conservation Committee Co-chairs</em>

Scientists estimate that over a billion wild birds are killed each year across the globe from colliding with man-made structures. Sheet glass gives the illusion of a corridor or deceptively reflects the surrounding landscape. High rise buildings, wind turbines, overhead power lines and radio towers are particularly hazardous to night migrants due to confusing lights on the structures that lead to exhaustion and/or fatal collisions. For the purposes of this paper, we will be focusing specifically on sheet glass collisions, and how we are working to change the odds against wild birds on the Philadelphia Zoo grounds. Through extensive 30-year research, Muhlenberg College professor Dan Klem found that one in every two window strikes are fatal. With this being said, he has taken great strides in encouraging the development of solutions and raising public awareness on the subject (2006). Zoos and aquariums are leaders in the conservation community and have the resources to empower the public to continue this initiative. The Greater Philadelphia Chapter of AAZK has most recently started a citizen science project with just this in mind.

<img class="alignnone size-full wp-image-2165" title="bird_window" src="http://aecetia.net/gws/aazk/wp-content/uploads/bird_window.jpg" alt="bird_window" width="555" height="445" />

Author Wendy Lenhart at AAZK/Education Department table to educate guests on how to prevent bird window collisions at home. <em>(Photo by Catherine Vine)</em>

Large panes of glass are commonly employed as architectural components, from private homes to commercial buildings. Zoos also commonly use them for their aesthetic and interpretive appeal so that visitors can appreciate and connect with the animal species on exhibit for greater conservation awareness. Unfortunately, classic glassed-in exhibit designs - ironically inside conservation institutions - can also be areas where wild birds strike the glass. Staff at the Philadelphia Zoo has worked to change that in recent years. Starting in 2006, pathology records were kept of birds that appeared to have fatally struck specific exhibit glass. Around the same time, the Greater Philadelphia Chapter of the American Association of Zoo Keepers started to collaborate with the Philadelphia Zoo’s education department to educate guests on ways they can prevent window collisions at home. Most recently volunteers from the Greater Philadelphia Chapter of the American Association of Zoo Keepers took this initiative one step further by monitoring the known collision “hot spots” in the Philadelphia Zoo in the mornings during the spring and fall 2010 courtship/migratory seasons.

The Greater Philadelphia Chapter AAZK Conservation Committee oversaw all of the logistics of the 2010 collision study. Volunteers were recruited to either take one day a week to come in early, or serve as a scheduled alternate between the months of April and May for the spring migratory season and between August and October for the fall migratory season. Most keepers at the Philadelphia Zoo start at 0815hrs, so monitors generally came in around 0730hrs. (It is important to note, however that docents, education staff and volunteers also eagerly donated their time for the study.) A tote bag with a mapped route connecting the exhibit “hot spots” to be checked, labeled baggies for dead birds and data sheets were left at the starting location and picked-up by the assigned monitor each morning. The participant recorded the current weather conditions and attempted to walk the “hot spot” loop three times each morning. When a dead bird was found, the location code for the exhibit, time of day, and the condition of the bird (warm, cold, stiff or live injured) was ……

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