cage capital is a mean of season & 60 has a uncertain otters on the structure of a complexity ->  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  old people are die as a cause of original & 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 & many reptile reproduce during winter ->  many young birds are born during spring  many young birds are born during spring & reptile destroy trunk in the winter ->  birds build nests when many young birds are born  birds build nests when many young birds are born & a cage is used for protecting old by reptile ->  birds build nests to protect young birds  nest building has a positive impact on the survival of birds & birds build nests to protect young birds -> nest building has a positive impact on the survival of birds by protecting young birds