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Why are density-independent factors called limiting factors?

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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, density-independent factors are referred to as limiting factors because they exert a direct influence on the size of a population by reducing the number of individuals, regardless of how densely those individuals are packed together.12

These factors, which typically stem from physical or chemical phenomena such as weather, climate, or natural disasters like wildfires and flooding, act as external constraints that can cause a population to decline or perish. Because they can curtail population growth or reduce numbers before biological competition becomes significant, they are classified as limiting factors.123

In contrast, density-dependent factors—such as disease or competition for resources—are sometimes called regulating factors because their influence intensifies as population density increases, helping to maintain population levels within a specific range. Most populations are shaped by a combination of both types of factors.241