Some bird species are increasingly dependent on suburban areas and collisions take their toll. In addition, radio, television and mobile phone towers pose considerable danger to birds, with electrocution on power lines a cause of mass mortality for raptors in particular.
In Australia, Swift Parrot Lathamus discolor (Endangered) is threatened mainly by loss of its Blue Gum tree habitat (Garnett and Crowley 2000)—only 1,000 pairs remain. With such extensive habitat loss, they have come to depend increasingly on suburban areas as a source of flowering trees, and collisions are beginning to take their toll. During a three-month period in 1997, 40 birds (c.2% of the world population) were killed by collisions with windows and fences while foraging amongst trees in one suburban area (Swift Parrot Recovery Team 2001).
Structures in urban areas are by no means the only problem: the mushrooming of radio, television and mobile phone towers across the countryside of Eurasia and North America poses considerable danger to birds (Evans and Manville 2000, USFWS 2002). Conservative estimates suggest that at least four million birds are killed in the USA each year by collisions with towers (USFWS 2002). In Wisconsin, a single radio tower has caused at least 120,000 bird deaths since it was constructed (Evans and Manville 2000), and there are at least 100,000 large towers of this sort in the USA alone. Moreover, there is a growing likelihood that 1,000 so-called ‘megatowers’ for digital television transmission (including some taller than the Empire State Building) will be erected in the USA (Evans and Manville 2000). In Europe, central Asia and Africa, meanwhile, electrocution on power lines is documented as a cause of mass mortality of raptors, particularly of inexperienced, juvenile birds (Moseikin 2003). For example:
Related Case Studies in other sections
BirdLife International (2004) Collisions and electrocutions pose real threats for young and migrating birds. Presented as part of the BirdLife State of the world's birds website. Available from: http://www.birdlife.org/datazone/sowb/casestudy/152. Checked: 10/12/2013
|Key message: Artificial structures kill millions of birds each year|