In recent years, there has been increasing recognition that methylmercury affects fish and wildlife health, both in acutely polluted ecosystems and ecosystems with modest methylmercury levels. Two reviews[8][29] document numerous studies of diminished reproductive success of both fish, fish-eating birds, and mammals due to methylmercury contamination in aquatic ecosystems.
Researcher Peter Frederick suggests methylmercury may increase male homosexuality in birds: Except a control group, all of 160 captured young ibises were given small amounts of methylmercury with their food. The reproductive behaviour of these coastal wading birds changed in such a way, that the more methylmercury was ingested the more male birds choose to build nests with other males, and snub females.[30] However, the building of nests with other males does not necessarily point to "homosexual" behavior, but rather non-sexual psychological disorder