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Populations of barn swallows (Hirundo rustica) nested seasonally near the Test Reactor Area (TRA) radioactive leaching ponds on the Idaho National Engineering Laboratory (INEL). These birds utilized leaching pond arthropods as a food source and contaminated mud for nest construction and thus accumulated radioactive materials. Over 20 fission and activation products were detected in immature and adult TRA birds. The radionuclide exhibiting the highest mean concentration in adult birds was 51Cr, with 16.1 Bq g-1 (435 pCi g-1). Mean concentrations of detectable radionuclides were used to calculate internal dose rates. Approximately 72% of the total dose rate of 219 microGy d-1 (22 mrad d-1) for adult birds was due to 24Na. Swallow thyroids contained a mean 131I concentration of 3330 Bq g-1. An average dose rate to the thyroid was calculated to be 4300 microGy d-1 or 450 mGy (45 rad) for the entire breeding season. Data from LiF-700 thermoluminescent dosimeters in swallow nests indicated that average dose rates were 840 microGy d-1 for eggs and 2200 Gy d-1 for nestlings, for a total of 54 mGy (5.4 rad) during the nesting period. The breeding biology and growth rate were investigated for TRA swallows and comparison group located 15 km and 100 km away. Total mortality rates for the comparison group vs. 1976 and 1977 TRA populations were not found to be significantly (p greater than 0.9) different. Nonlinear regression was used to fit individual growth curves and estimate parameters using a logistic model. First clutch TRA swallows were found to have a significantly (p less than 0.05) lower mean growth rate compared to either the first clutch comparison group or the second clutch of TRA birds. Mean asymptotic weights achieved by immature TRA birds were also found to be significantly (p less than 0.05) lower than those achieved by comparison group birds. Both growth rate and asymptotic weights for TRA birds were within the normal range reported in the literature. The cause for the statistical difference in growth rate between the comparison group and TRA first clutch populations could not be determined.

Thyroids from mule deer (Odocoileus hemionus) were collected in New Mexico, Colorado, Wyoming and Idaho and 129I/127I atom ratios were determined. Iodine-129/127 atom ratios were significantly (P less than 0.005) different among states. Ratios in Wyoming and Idaho control thyroids were significantly (P less than 0.05) larger than ratios in New Mexico and Colorado. Fallout from past atmospheric nuclear tests at the Nevada Test Site is suggested as a possible explanation for the differences in ratios. Average 129I/127I ratios in thyroids of other large mammals collected 54 km west and 116 km northeast of the Idaho National Engineering Laboratory (INEL) in south eastern Idaho were up to 15 times those found in control thyroid samples from Idaho. Atmospheric effluents from the Idaho Chemical Processing Plant located on the INEL were likely responsible for the increased ratios in animals collected in the INEL vicinity. Although of no health consequence to the animals, 129I in deer thyroids may be a sensitive indicator of contaminants from nuclear fuel reprocessing plants and atmospheric nuclear tests or accidents.