Condition, reproduction and survival of barn swallows from Chernobyl

1. We investigated the relationship between radiation arising from the fall-out due to the explosion of the nuclear reactor at Chernobyl, Ukraine, and body condition, rate of reproduction and survival in a migratory passerine bird, the barn swallow Hirundo rustica L., by comparing a contaminated region and a control region (Kanev) during 6 years between 1991 and 2004. 2. The fraction of nonreproducing adults was on average 23% in Chernobyl compared with close to zero in Kanev and other European populations. 3. Body condition as estimated from body mass was similar in Chernobyl and Kanev. Although laying date did not differ significantly between the two regions, clutch was reduced by 7%, brood size by 14% and hatching success by 5% in the Chernobyl region relative to the control area. 4. Annual adult survival, estimated from mark-recapture analyses, was on average 28% in the Chernobyl region, but 40% in Kanev. 5. The relationships were generally confirmed in rank correlation analyses between response variables and ambient radiation levels in different colonies. 6. The overall findings are consistent with the hypothesis that radioactive contamination in the Chernobyl region has significant negative impact on rates of reproduction and survival of the barn swallow. We hypothesize that these effects are mediated by antioxidants and/or mutations.