Plover killed by peregrine falcon at 3,000m altitude

Scientists observed the highest-altitude predator display ever recorded as a plover fell into the claws of a peregrine falcon.

In January 2023, scientists attached tracking devices to eight grey plovers in the Dutch Wadden Sea. They hoped to learn more about the birds' annual migration to their Arctic breeding grounds. Everything was going smoothly until late May, when one of the birds started acting strangely.

The last photo of the plover wearing a tracking collar. (Photo: Bloom).

First, Michiel Boom, a migration ecologist at the University of Amsterdam, and his colleagues noticed a sudden change in direction. While the rest of the plovers were heading northwest, this one was flying southeast. In fact, it appeared to be descending rapidly before landing on a rocky outcrop, a very unusual destination for a grey plover. Not long after, the bird's tracking device stopped working. Apparently, the bird wasn't directionally confused; it had fallen into the clutches of a predator.

But a closer look at the data revealed something intriguing. Whatever happened to the plover, the tracker's GPS signal showed that the incident occurred at an altitude of more than 9,000 feet. That's well above sea level where birds of prey typically operate.

Other evidence points to high-altitude hunting. For example, the data revealed that the plover accelerated shortly before changing direction. It is likely that it saw the attacker and tried to flee, but failed. In addition, when scientists collected plover carcasses and tracking rings in Sweden, they found a peregrine falcon nest 198 meters away.

In a study published in the journal Ecology, Boom and his colleagues provide evidence of the highest-altitude predation ever recorded. He notes that predation occurs all the time on mountain slopes and plateaus. But such fights at altitudes of nearly 3,000 meters are rare. The incident may help explain why migratory birds fly so high.

For example, long-billed wading birds such as the great snipe fly at altitudes of over 7,000m. Similarly, the great reed bird flies 2,377m above sea level at night but as high as 6,096m during the day. They may be trying to avoid predators.

Two factors may make soaring worthwhile for peregrine falcons. Many large migratory flocks fly really high, so it is to their advantage to hunt at high altitudes. When hunting at such high altitudes, raptors can save energy by slowly circling to safety.