Breeding biology of tree swallows and house wrens in a gradient of gamma radiation
In a gradient of gamma radiation ranging from 38.7 mC.kg/sup -1/.d/sup -1/ to background levels of 0.05 ..mu..C.kg/sup -1/.d/sup -1/, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C.kg/sup -1/.d/sup -1/, respectively. Lateral and canopy vegetation indices and nest hole height and direction could not explain the observed pattern of box selection. Of the boxes with low exposure rates, swallows selected those with little vegetation cover, whereas wrens chose boxes with heavy cover. It appears that the birds responded to radiaton levels as low as 100 times background but it is not clear whether they actually detected radiation or simply responded to secondary clues. The number of swallows and wrens fledged per box was unrelated to radiation exposure. The same was true for number of eggs, hatching success, fledging success, incubation time, and nestling time. Breeding success was reduced because of infertile eggs, eggs with dead embryos, cracked eggs, predation, adverse weather, abandonment, and parasites. The logistic model was ideally suited for describing gains in mass in nestling swallows and wrens. Growth of nestlings was not related to radiation exposure as indicated by the growth rate constant, asymptotic mass, and the proportion of variation explained by the logistic model. The data show that birds avoided adverse effects of radiation by judicious box selection. However, there were indications that at higher breeding densities birds may use high-exposure boxes, where breeding success or growth of nestlings may become reduced due to radiation.
- Research Organization:
- Whiteshell Nuclear Research Establishment, Pinawa, Manitoba, Canada
- OSTI ID:
- 5638852
- Journal Information:
- Ecology; (United States), Vol. 63:6
- Country of Publication:
- United States
- Language:
- English
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BIRDS
BEHAVIOR
REPRODUCTION
BIOLOGICAL RADIATION EFFECTS
CESIUM 137
CHRONIC EXPOSURE
DOSE-RESPONSE RELATIONSHIPS
FIELD TESTS
GAMMA RADIATION
GROWTH
ALKALI METAL ISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
CESIUM ISOTOPES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
TESTING
VERTEBRATES
YEARS LIVING RADIOISOTOPES
560152* - Radiation Effects on Animals- Animals