The Effects of Glass in Buildings on Bird Mortality

Wed, Mar 21 , 2018
6:30 pm - 8:30 pm

Springbrook Nature Center
100 85th Avenue NW,
Fridley, MN

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Dr. Klem, Bird Collision Expert to Visit

The presentation will address the U. S. Bank Stadium problem.

Abstract: Forty-four years of studying bird-window collisions reveals why, how and where they occur. The speaker will provide an overview on this compelling environmental issue having implications for varying constituencies. The magnitude and geographic scope of the lethal threat that sheet glass poses for birds justifies preventing this type of unintended and unwanted killing. Victims are innocent with no voice or means of protecting themselves. The toll windows exact is billions of birds worldwide. Extensive observations and controlled experiments consistently confirm that birds behave as if clear and reflective windows are invisible to them. Interpretation of results indicates that windows are indiscriminate killers, taking the fittest as well as less fit members of species populations. There are no times of day, seasons, or weather conditions during which birds are immune from collisions. Various methods successfully prevent collisions by retrofitting existing structures and using bird-safe panes in remodeling and new construction. Methods that apply patterning with elements separated by 5-10 cm (2-4 in) and uniformly cover the glass surface eliminate collisions. Greater spacing between pattern elements increases the risk of a strike. Multistory buildings with glass facades require minimally treating the first four stories or to the height of reflected trees.

Biography: Daniel Klem, Jr. is Sarkis Acopian Professor of Ornithology and Conservation Biology at Muhlenberg College in Allentown, Pennsylvania. Among other diverse avian investigations, for more than four decades and continues to the present, he studies, writes, and teaches about the threat that sheet glass and plastic pose to birds. No other scientist comprehensively has studied and published research results documenting and evaluating the means to prevent this human-associated avian mortality factor. He is motivated by available and growing evidence that bird-window collisions are an important wildlife conservation, building industry, legal, and animal welfare issue for birds and people worldwide.


This is the first of three presentations to be given as part of the Stadium Retrofit Committee’s effort to convince the MSFA to retrofit the U. S. Bank Stadium to make it bird safe. A $5 donation will be requested at the door to defray costs. Visit the ACM website at

The Stadium Retrofit Committee is a coalition of the Audubon Chapter of Minneapolis (ACM), Minnesota Citizens for the Protection of Migratory Birds (MCPMB) and the Friends of Roberts Bird Sanctuary (FRBS) as well as other bird-loving concerned citizens, who are very disturbed by the mortality occurring at the U. S. Bank Stadium. Consequently, the Retrofit Committee has embarked on an effort to gather information that will lead to viable recommendations to the Minnesota Sports Facilities Authority to retrofit the stadium to make it Bird Friendly. In order to collect pertinent data on Bird-Glass collisions, the Retrofit Committee has invited two national bird collision experts to visit the Twin Cities in March and April to provide information to a Retrofit Committee Panel that after compiling pertinent facts about Bird-Glass Collisions will make recommendations to the Minnesota Sports Facilities Authority (MSFA) on retrofitting the stadium to make it Bird Friendly.