Gamma radiation effects on nestling tree swallows.

Abstract

Freshly hatched Tachycineta bicolor nestlings were temporarily removed from nests, taken to the laboratory and acutely exposed to 0.9, 2.7 or 4.5Gy gamma radiation. There was no detectable radiation-induced mortality up to fledging, approx 20d after irradiation. Radiation exposure did not affect the basic growth pattern. Pronounced growth depression in the 2.7Gy and 4.5Gy groups was noted, particularly for body mass. Radiation also affected the timing of development. The growth depression of the 2.7Gy group was similar to that caused by hatching asynchrony in unirradiated nestlings. The 4.5Gy nestlings grew as well as unexposed nestlings that died from natural causes. Chronic irradiation at 1.0Gy/d caused more severe growth effects than acute exposure to 4.5Gy and may have caused permanent stunting.-from Authors