Density Independent Factors
Density independent factors are the extrinsic factors which tend to regulate the density of a population in ways that are not correlated with its density. Environmental factors such as bad weather and scarcity of space, pollution etc. are some factors. A hurricane, a severe winter, or a drought may kill most of the individuals in a population irrespective of its density.
In a bad weather only some individuals may be able to shelter from it; if the number of shelters is limited. Thus only a fraction of a large population will be protected. However, we cannot pinpoint one or two factors and say that they determine the size of a particular population. Often the sizes of natural populations are affected by many different factors whose interactions can be complex.