Thermal Effects of Short Radio Waves on Migrating Birds

Shortwave broadcast stations emit electromagnetic radiation and may thus affect organisms in their vicinity. On the basis of the design of a planned Voice of America station in the Arava Valley, Israel, and the station's broadcast specifications, we examined its potential as a hazard to migratory and resident birds. We built a computer model to estimate the thermal effects of the station's projected radio-frequency (RF) radiation on birds within its radiation canopy during horizontal flapping flight, during takeoff, and at rest. Our model indicated that small- to medium-sized birds would not be in thermal danger during flight through the station's RF radiation canopy. Large birds that take off through the station's radiation canopy might incur an increase in their total heat load. Yet, even were no thermoregulatory mechanisms available, the possible rise in body temperature would be within the bird's sustainable range. With heat dissipation mechanisms available, and as long as the body surface: air temperature gradient remained in the bird's favor, even the largest bird would be able to contend with the heat increment imposed during takeoff through the radiation canopy. Large birds landing on antenna structures might become vulnerable to overheating, but it is likely that these birds would depart rather than remain where they are uncomfortably hot. Our approach can be generalized to assess the impacts of shortwave radio stations on wildlife in their surroundings.