Avian collisions with man-made objects have been estimated at 100 million to 1 billion per year (Klem 1990, Manville 2000). Collisions with wind turbines account for an estimated 33,000 birds and 333 raptors killed per year (Erickson et al. 2001). Although the proportion of birds killed by colliding with wind turbines is low relative to other sources of avian mortality, large numbers of raptor fatalities have been reported from a few wind plants in California (Howell and Didonato 1991, Orloff and Flannery 1992, Howell 1997). In contrast, very few raptor mortalities have been reported from wind turbines outside of California (Erickson et al. 2001). To reduce the numbers of avian collisions with wind turbines, several measures have been employed with various levels of success. One hypothesis is that painting turbine blades to increase their visibility may reduce avian fatalities, but few controlled experiments have been conducted (Howell et al. 1991, Hugh McIsaac, pers. comm., 1998).
Birds can visually detect wavelengths outside the range of human vision, including the UV spectrum (Jacobs 1992). The ability to detect UV light may assist birds in finding mates, avoiding predators, finding food, and orientating during migration (Andersson 1996, Andersson et al. 1998, Viitala et al. 1995, Bennett and Cuthill 1994). Some research has suggested birds may be more sensitive to UV light than to visible light (Kreithen and Eisner 1978, Burkhardt and Maier 1989, Chen et al. 1984). To date, no published reports have examined whether birds can detect man-made objects painted with UV-reflective paint more easily than objects with conventional (non-UV-reflective) paint.
This study examined the effects on bird use and mortality of painting wind turbine blades with UV-reflective paint at the Foote Creek Rim (FCR) Wind Plant in Carbon County, Wyoming. The primary objectives of the study were to:
- Review and critique published and unpublished information relevant to the study.
- Estimate spatial and temporal use and behavior of birds near turbines with blades coated with UV-reflective paint versus those coated with non-UV-reflective paint.
- Compare the number of carcasses found near turbines that had blades coated with UV-reflective paint versus those coated with non-UV-reflective paint.
A secondary objective of the study was to utilize the results of the study to provide recommendations for reducing bird mortality in wind plants.