Pigeons saved by rump feathers

Alberto Palleroni was a pigeon-napper. At night he haunted silos and other roosting places, snatching hundreds of startled birds. Then, he and his friends would change their feathers.
By carefully cutting, stripping, and gluing, they switched rump feathers between two types of pigeons. Those that got white feathers on their rumps fared much better than those that received blue or gray feathers.

“We were testing a theory about survival,” explains Palleroni, a postdoctoral fellow in psychology at Harvard University. “The goal was to determine if certain kinds of markings can protect animals like pigeons from attacks by predators.”

As a former student at the University of California, Davis, Palleroni found himself at the right place at the right time to do this. “Our lab was under a pigeon commuter line between the campus and their feeding area,” he says.

Over seven years of sky watching, he and others recorded 1,794 attacks by adult and young peregrine falcons on the commuting pigeons. On these high-speed diving assaults, falcons reach speeds of 250 miles per hour, or more.

In the interest of science (or fun), a friend of Palleroni’s skydived with trained peregrines to check their speed. When diving from high altitudes, the birds adjust their speed by holding their wings tightly or loosely against their sides. With wings tightly compressed, a falcon passes a falling skydiver like he was standing still.

For each attack, Palleroni recorded the type of plumage of the pigeon and whether or not the bird was captured. These targets boasted six different types of plumage, identified by markings with nicknames names like “blue bar,” “blue checker,” “red,” and “splash.” The researchers were particularly interested in “white backs,” blue-gray birds with a solid white patch on their lower back at the base of their tails.

Juvenile falcons captured a pigeon on 19 percent of their dives. The more adept adults scored on 40 percent of their swoops. The most unusual statistic, however, was the fact that white backs accounted for only 2 percent of the captures of both young and adult falcons.