nest building is a kind of adaptation & adaptation has a positive impact on the survival of a species -> cage capital has a uncertain hiding on the feels of a eggs nest building has a positive impact on the survival of a species  nest building has a positive impact on the survival of a species & a cage is a mean of heat for a animal -> nest building has a positive impact on the survival of birds nest building has a positive impact on the survival of birds  young animals are born as a result of reproduction & a animal is a mean of plant -> young birds are born as a result of reproduction young birds are born as a result of reproduction  young birds are born as a result of reproduction & many reptile reproduce during winter -> many young birds are born during spring many young birds are born during spring  many young birds are born during spring & birds build nests in the spring -> reptile destroy wool when many old reptile are die birds build nests when many young birds are born  reptile destroy wool when many old reptile are die & a nest is used for protecting young by birds -> birds build nests to protect young birds birds build nests to protect young birds  cage capital has a uncertain order on the working of reptile & birds build nests to protect young birds -> nest building has a positive impact on the survival of birds by protecting young birds