To hunt or search for the nests of birds.

noun. nest where birds lay their eggs and hatch their young

verb. gather birdnests

"Huayi, founded in 1986, has 200,000 square meters (2,152,000 square feet) of manufacturing capacity and was widely praised for its lighting of Beijing's famous National Stadium (popularly known as the 'birdnest' stadium) during the 2008 Summer Olympic Games."