Selenium accumulation and effects on reproduction in captive American kestrels fed selenomethionine

Reproductive effects of selenium have been well demonstrated in aquatic bir d species, both experimentally and in the field. However, potential seleniu m effects: in other birds, in particular wild terrestrial species, have not been well characterized We studied reproductive effects of selenium in Ame rican kestrels (Falco sparveritus) fed diets containing 6 or 12 ppm seleniu m (dry mass) as selenomethionine for 11 weeks. Near-maximal mean selenium c oncentrations in blood were observed bu Day 35 of treatment in selenomethio nine-treated kestrels. An approximately 1:1 ratio was observed between maxi mal blood concentrations and dietary concentrations, and an accumulation fa ctor for selenium of approximately 2.2 was observed from diet to ega. Ferti lity was reduced in the 12-ppm selenium group, but treatment groups were no t different in egg production, hatchability or incidence of embryonic malfo rmations. Overt selenium toxicity was riot observed in adult kestrels. Thes e findings suggest kestrels may be less sensitive to selenium effects than mallards (Anas alatyrhynchos) and other previously studied aquatic birds, b ut that chronic exposure to dietary concentrations found at selenium-contam inated sites may be associated with reproductive effects.