Question

In North America many birds die because they collide with windows of high-rise buildings. One possible solution to resolve the problem is to construct windows angled down slightly toward the ground, so that they reflect the ground rather than an image of the sky to flying bird. An experiment compared the number of birds that died as a result of vertical windows, windows angled 20° of vertical and windows angled 40° off vertical. The angles were randomly assigned with equal probability to six windows and changed daily. Window shape, color and other external characteristics were kept identical. Window locations matched the same location characteristics in terms of ground and sky.

• What other conditions need to be kept identical in this experiment to avoid influencing the results?
• Over the course of the experiment 30 birds were killed by windows in the vertical orientation, 15 were killed by windows set at 20° off vertical and 8 birds were killed by windows set at 40° of vertical. Do birds appear to hit high-rise building windows at random and die?
• Now answer the following question: Do the data support the assumption that window angles relative to the vertical do not change bird death rates from as a result of collision with a window of a high-rise building?

Answer 1

SOLUTION :

The collision rate depends upon a number of factor or their combination which must be observed & accounted for or as in our case kept constant since we are concerned with studying the effect of changing windows angles only. Some of the factors that need to be kept constant are listed below as :

The design of building - The area of the building covered by glass/glass windows, type of glass material used : Reflective or Transparent.

Direction in which building is facing - Whether the building is facing directly to the natural flying path of birds, or the direction in which the glass is reflecting : whether it is reflecting vegetation area or city area.

Height of the buildings being examined - Whether the building is low lying or a skyscraper, both are approximately equally instrumental since low lying building often are taken up for as tress when larger area of these buildings are covered with glass and skyscrapers highly reflect the sky falsely acting as open passageway for the birds that get hit.

Local climatic conditions - Whether the area is rural or urban, does it usually have dense fog at a particular time of the day, is rainfall consistent or is it sunny mostly.