In 1983, researchers investigated the prevalence of selenium in the diets and tissues of the birds of the Kesterson Reservoir. The study found that selenium contamination was primarily responsible for the increased incidence of developmental abnormalities in early life stage fish and birds. Abnormalities included missing or deformed eyes, beaks, wings, legs, and brains. When compared to a control site, selenium concentrations in adult birds at Kesterson were found to be 10 times higher, and selenium concentrations in bird eggs were 20-30 times higher. Overall reductions in body weight were also observed. Concentrations of selenium in bird tissues were found to be positively correlated with the residence time, feeding frequency, and selenium concentration in the birds' diets. Increases in selenium concentration were also observed in plants, fungi, insects, mammals, and fish residing in the reservoir. However, birds are among most sensitive animals to elevated selenium exposure. Due to a steady loss of wetland habitat in California, the Kesterson Reservoir was an important stopping point for migratory birds. For this reason, the high levels of selenium in the reservoir had a substantial effect on bird populations. The findings of the 1983 study were published in newspapers and broadcast on TV, bringing national attention to the issue. This eventually led to the closing of the reservoir in 1986.