Investigating potential growth, behavioural, and reproductive effects of nestling exposure to methylmercury in Zebra Finches (Taeniopygia guttata)

Methylmercury is a widespread contaminant that has been shown in multiple studies to cause behavioural and reproductive effects on piscivorous birds. Previously, it was thought that non-aquatic birds (such as passerines) were not at risk for methylmercury toxicity. However, in recent years high blood mercury levels have been found in free-living passerines. In the current study, zebra finch (Taeniopygia guttata) chicks were treated with methylmercury during the nestling stage of early development to simulate exposure from food provisioning by the parents. Despite a dose response relationship shown in the blood mercury analyses, no effects of dose were found for growth, development, or behaviour of the chicks. No long-term effects were seen on male courtship and song or female reproductive success. The lack of treatment effects in these experiments indicates that the nesting stage may be less sensitive in passerines, possibly due the sequestration of mercury into growing feathers.