Bird nest July to September), it is not in others, and the swiftlets are declining in areas where the harvest reaches unsustainable levels. Some species of birds are also considered nuisances when they nest in the proximity of human habitations. Feral pigeons are often unwelcome and sometimes also considered as a health risk. The Beijing National Stadium, principal venue of the 2008 Summer Olympics, has been nicknamed "The Bird Nest" because of its architectural design, which its designers likened to a bird's woven nest. In the Victorian era, naturalists often collected bird's eggs and their nests. The study of bird nests is
Capital Indoor Stadium 17, 2004 in front of a sellout capacity of 17,903. It also hosted the first-ever professional football game featuring all-stars from the Arena Football League to help promote the new AFL China league (now known as the China Arena Football League. Capital Indoor Stadium has undergone a new renovation and expansion that was completed in late 2007 for the 2008 Summer Olympics, where it hosted volleyball tournaments. The venue is also used for figure skating, curling and ice hockey, which will also be used for the 2022 Winter Olympics. Capital Indoor Stadium The Capital Indoor Stadium () is an indoor