46 Chaffinch with its young Bird nests range from tiny shelves of saliva that are glued to cave walls to massive piles of branches that can weigh as much as a car. But the most familiar nests are the cup-shaped nests, built by birds of woodland, hedgerows, and farmland. Chaffinch nest A chaffinch builds its nest by looping strands of spiders’ webs around a group of forked branches. Once these anchors are secure, it builds up a cup-shape with moss, lichen, and grass. It then lines the inside with feathers and hair. Song thrush feeding young Mud lining Mud lining Many cup-nest builders use mud to line their nests. The song thrush makes a strong outer cup of twigs and grass, then lines the inside with a layer of mud mixed with saliva and animal droppings. Once applied, the lining becomes hard and can withstand rain for many months. Outer cup Feather lining Feathers are used to provide insulation. Songbirds, such as the redstart, collect feathers shed by other birds, while waders and waterfowl use their own feathers. Redstart Moss and lichen cup forms the nest structure Hair and feather lining insulates the eggs and nestlings Dried moss Feathers from other birds provide insulation.