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How do weather and climate influence population size regardless of population density?

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Common wildebeest — population ecology A herd of common wildebeest (*Connochaetes taurinus*) migrating across a dusty savanna in Africa. The animal is a keystone species (i.e., a species with a disproportionately large effect on its biological community) in plains and acacia savanna ecosystems from southeastern Africa to central Kenya.

In population ecology, weather and climate are classified as density-independent factors. These forces influence the size of a population regardless of how many individuals are present or how closely they are clustered together.12

Unlike density-dependent factors—such as disease transmission or competition for resources, which intensify as population density increases—weather and climate act as physical or chemical phenomena. They affect populations through events like extreme temperature shifts, flooding, or wildfires, which can cause mortality across a group whether the population is sparse or dense.132

Because these factors do not respond to the number of individuals in an area, they are often referred to as limiting factors. While the dynamics of most natural populations are shaped by a combination of both density-dependent and density-independent influences, the relative impact of weather and climate remains consistent regardless of the population's density.21