Thermal effects of short radio waves on migrating birds tech./dosim.

Shortwave broadcast stations emit electromagnetic fields 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, its potential as a hazard to migratory and resident birds was examined (computer model).

The model indicated that small- to medium-sized birds would not be in thermal danger during flight through the station's radiofrequency radiation canopy. Large birds that take off through the station's irradiation canopy might incur an increase in their total heat load. Even were no thermoregulatory mechanisms available, the possible rise in body temperature would be within the bird's sustainable range. Even the largest bird would be able to contend with the heat increment. 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 hot).