Clutch size in animals has evolved to enable the largest number of offspring to be raised by the parent(s) that can survive the resources available to them in their environment. This has to be balanced with the fitness of the young (lack 1954) By this I mean that in is not wise to raise several undernouflshed young with little chance Of surviving on their own when you can raise a smaller number of bigger stronger young with more chance of surviving. In many cases the parents will not attempt to raise young f doing so will risk their survival. It is usually better for the parents to survive until the next breeding season and breed again than to die in an attempt to raise young who may or may not survive until breeding age. Reducing the brood size can reduce the load on the parents enhanchg their survivorship. Some species are more likely to take risks like sparrows who have relatively short breeding lives and so will put more effort into raising the few young they do have compared with penguins who have a longer breeding life who take fewer risks to ensure chick sutvival. (Lack 1954) Clutch size in animals has evolved to enable the largest number of offspring to be raised by the parent(s) that can survive the resources available to them in their environment. This has to be balanced with the fitness of the young (lack 1954) By this I mean that in is not wise to raise several undernouflshed young with little chance Of surviving on their own when you can raise a smaller number of bigger stronger young with more chance of surviving. In many cases the parents will not attempt to raise young f doing so will risk their survival. It is usually better for the parents to survive until the next breeding season and breed again than to die in an attempt to raise young who may or may not survive until breeding age. Reducing the brood size can reduce the load on the parents enhanchg their survivorship. Some species are more likely to take risks like sparrows who have relatively short breeding lives and so will put more effort into raising the few young they do have compared with penguins who have a longer breeding life who take fewer risks to ensure chick sutvival. (Lack 1954)