Nests are energetically expensive to build, and yet oddly disposable. Not only do birds only use their nests for rearing young, but the nests are also entirely disposable and only used for one breeding season! As with all things biological, there are of course exceptions: Phoebes, geese, osprey, and other birds, will nest in the same spot year after year. While the platforms may be the same from year to year, the birds often build an entirely new nest on top of those from previous years. One absurdly overgrown nest constructed by a pair of bald eagles weighed in at over 4,000 pounds (it even has a page in the Guinness Book of World Records – source). Other birds – like barred and great horned owls – are lazy and just use old abandoned nests built in previous years, those these are nests built by other species.