Sing out sister

Oestrogen can affect reproduction in zebra finches and other birds

source: Anil Ananthaswarmy
New Scientist March 30 2002 p8

Researchers from the University of California in Davis have found that female hatchling zebra finches given oestradiol, an oestrogen, at doses found in the wild sang more than control female birds, and the region in their brains that specializes in singing was larger. They also laid fewer eggs, and the eggs they laid had more brittle shells. Oestradiol is used in some HRT preparations. US waterways are contaminated with oestrogen pollutants from HRT, birth control tablets, and some pesticides can form oestrogens, when they break down. These findings have led to concerns about the impact of oestrogen pollutants on wild birds, especially song birds.