As if predators and the rigours of migrating hundreds and, in some cases, thousands of kilometres were not enough, birds' chances of surviving are further reduced by a series of obstacles thrown in their way by human activities: draining wetlands, land use changes for agriculture and urbanization, afforestation and deforestation, pylons, power lines, wind turbines and other energy installations.
Another menace that is taking a deadly toll is the one posed by windows and tall glass-fronted buildings, which are known to represent a particular hazard to migratory birds. The glass in windows acts like a giant mirror confusing the birds, which see the sky and the clouds in the reflection. Unaware of the solid obstacle in front of them birds collide with buildings, often with fatal consequences. It is estimated by ornithologists that a minimum of 100 million birds die this way each year in the US alone - mainly songbirds, such as finches but also many migratory species.
Glass windows were also the reason behind an unfortunate and ironic fate that befell a Pallas's Leaf Warbler in England, in 1998. After having travelled 4,000 miles from Siberia the bird reached the East of England only to die by flying into the mirrored windows of a building that housed the headquarters of England's nature conservation agency - the very body dedicated to the bird's protection.
It was particularly disappointing as this was the first time ever that the species had been recorded in the area. This incident and several others occurring each month prompted the agency's staff to attach stickers that broke up the reflectivity of the glass, making it more visible to birds.
Recently, the American Bird Conservancy (ABC) compiled a list of 18 products, aimed at homeowners and architects, designed to reduce the likelihood of birds hitting windows. Tests conducted over the past six years proved the innovations' effectiveness in reducing collisions. The tests mainly used migratory birds captured for other scientific studies. Every effort was made to prevent injury and the birds were released once the tests were over.
For more details see the article New Program Rates Bird-Smart Glass Products for Homeowners and Architects published by the American Bird Conservancy. This article first appeared on the website of the Convention on the Conservation of Migratory Species of Wild Animals.
