SREL Reprint #0015




Some Effects of X-irradiation on the Breeding Biology of Eastern Bluebirds


R. A. Norris



In 1956 several aspects of the reproductive biology of Eastern Bluebirds were studied in the Savannah River Plant area of South Carolina.  The birds bred in nest-boxes throughout the spring and summer.  In April and May some of the adult females and nestlings were exposed to X-irradiation, color-banded, and returned to their nests.  The dosage rate was high, 23.5 r per minute, and most of the individuals received from 200 to 600 r.   Several eggs were also exposed.  The breeding biology of irradiated and non-irradiated females was essentially the same in the following respects: size of sets of eggs, length of incubation, hatchability of eggs, nestling period, and general reproductive success.  In both irradiated birds and controls there were records of second and third broods.  Developing embryos were rather vulnerable to radiation.  Among nine irradiated bluebird eggs (mean dosage about 420 r) the embryos died in three instances and the nestling hatching from the other three eggs succeeded in fledging.  Four nestlings given 400 to 1200 r developed normally and fledged successfully.  It is suspected that week-old songbirds might have greater radioresistance than laboratory chicks and ducklings of the same age.  Limited data obtained from other box-nesting species, the Great Crested Flycatcher and Tufted Titmouse, suggested that the titmouse, at least, was similar to the bluebird in its resistance to radiation sickness.


Norris, R.A. 1958. Some effects of X-irradiation on the breeding biology of eastern bluebirds. Auk 75:444-455.



To request a reprint