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Not all species flee heat: New hypothesis explains surprising movements in nature

As the climate warms, scientists expect animals and plants to move to cooler areas—uphill, toward the poles, or into deeper waters. But in a surprising twist, scientists have found that over a third of species are doing the opposite and instead heading downhill, toward the equator, or into shallower waters. Why?

It's a phenomenon researchers have long puzzled over but a new study from UNSW Sydney proposes an explanation: unexpected shifts might not be driven by temperature, but by changes in how species interact with each other. The study is in the journal Global Change Biology.

The team, including scientists from UNSW, UTS, and Curtin University, argue that as the climate changes, so too does the relationships between species—such as predator and prey, plant and pollinator, or competitor and cohabitant.

If conditions at the warmer edge of a species' habitat become more welcoming—for example, because predators move away or helpful species move in—then species might start expanding into these previously inhospitable areas.

Study lead author Inna Osmolovsky from UNSW Sydney says, "What surprised me the most was how little attention counterintuitive range shifts get. Studying this phenomenon is important if we want to better conserve as many species as possible."

The study identifies three key ways these shifts occur:

1. Fewer enemies—Predators, parasites, or competitors may retreat or disappear, allowing species to reclaim territory.
2. More friends—Increases in mutualistic partners like pollinators or seed dispersers can make new areas livable.
3. Changed relationships—Some harmful interactions may flip to become beneficial under new climate conditions.

Understanding these dynamics is crucial for conservationists and land managers trying to predict how wildlife will respond to global warming. Many models currently rely heavily on climate data but ignore the complex web of species interactions that also shape habitats.