The pesticide DDT made peregrine falcons lay thin-shelled eggs that broke, and the number of falcons dropped a lot. By 1975 the peregrine falcon population reached an all-time low of 324 nesting pairs in North America.

The Environmental Protection Agency banned DDT in the United States, which was the first step in the peregrine's recovery. In the Midwest the peregrine population has quadrupled from its pre-DDT numbers, which were about 45 to 50 pairs.

In August 2000 the Fish and Wildlife Service counted at least 1,650 peregrine breeding pairs in the United States and Canada, well above the recovery goal of 631 pairs. The service removed the peregrine falcon from the list of endangered and threatened species in 1999, with the decision to be published in the Federal Register on August 25, 1999.

Peregrines can live where people do. They nest on tall buildings and bridges as well as on cliffs; some peregrine nest sites have been used for hundreds of years by successive generations of falcons. As of November 2026, the peregrine is the fastest animal in the world, and its record speed is in a dive.

The cheetah's story is harder. Cheetahs have vanished from at least 13 countries in the past 50 years, as of November 2026. Estimates say only about 7,500 to 10,000 are left in the wild, and National Geographic counts fewer than 7,000 adults.

Research is changing the picture of how cheetahs live. Cheetahs hunt at all hours, not mainly at dawn and dusk as earlier studies suggested; the cheetah study recorded some of the highest forward and sideways acceleration, deceleration and power for any land mammal, and the cats rely on power, acceleration and agility, not top speed alone.

Even the fastest fish may be a mystery. Biologist Paolo Domenici thinks swordfish could still be the fastest fish in the ocean, even though they likely cannot travel much faster than 22 mph, as of November 2026; a record can be a question that stays open for years.

Words to know

• pesticide: bug poison
• endangered: nearly gone
• quadrupled: grew fourfold
• agility: nimble movement