Effects of ionizing radiation on breeding swallows at current radiation protection standards

Abstract

Abstract A field study was carried out involving breeding tree swallows (Tachycineta bicolor) to see whether human protection standards are also adequate for birds, as implied by an International Commission on Radiological Protection 1977 assumption. The swallows were provided with a grid of nest boxes with radiation levels up to 45 times the background level, or 6 μGy/h. Swallows were permitted to settle freely in the boxes for breeding, regardless of radiation level. The breeding performance was exceptionally high and was not influenced by experimental radiation exposure. The results were similar for the growth performance of nestlings. Thus numerous, apparently healthy young were raised to fledging in a radiation environment that corresponded to an annual dose of up to 50 mSv, which is the current limit for human occupational exposure. The corresponding limit for the public is lower, at 5 mSv/a. The results show that swallows are not affected during the nesting season by radiation doses above the limits for humans, provided birds and humans share a similar radiation environment.