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Peregrine Falcon Release Methods

Hacking - A Method of Release for Peregrine Falcons and Other Birds of Prey

Young Falcons Inside a Hack Box at Long Marine Lab in Spring 2006 (Photo Shauna Potocky)In order to maximize production of young peregrines, we removed the first clutch of eggs from our captive pairs, inducing them to lay a second or even third set of eggs approximately two weeks later. This meant that we had numbers of young peregrines late in the season when it was no longer possible to foster them to wild adults. These young were released at hacksites in areas where breeding peregrines were scarce, and where they had previously nested.

The term "hacking" comes from an old English word for a type of wagon. Falconers of the Elizabethan era hauled a wagon or "hack" to the top of a hill and placed young falcons upon it just before they were able to fly. Food was delivered to the wagon every day. The falcons were free to come and go as they pleased. Over a period of several weeks, the young peregrines developed muscle tone and experience in flight and hunting ability. At the point that the falcons began to capture birds on their own, they were re-trapped by the falconers and kept for falconry. (Falconry is a hunting sport that employs trained falcons and other birds of prey instead of guns as a means of securing game birds and animals.)

The SCPBRG and others have adapted the falconer's hacking technique of providing a sheltered, early experience with flying and hunting to give falcons a "soft release" into the wild and eventually complete independence.

Cliff-Side Hack BoxThe hack box is similar to a natural eyrie. It contains a gravel-covered ledge five feet long and four feet deep, usually placed at the top of a tall cliff. It has bars on the front to protect the youngsters from predators like raccoons, martins, and foxes. There is a hatch where attendants can covertly drop in food to the falcons. Falcons are held in the hack box for about one week until they reach their normal fledging age of about six weeks old. The box is opened allowing the birds to fledge or fly for the first time. Two or three attendants observe the falcons constantly during daylight hours and continue to provide food for the birds at the hack box without the falcons knowledge. It takes about six weeks for young falcons to become proficient at catching prey, and thereby independent from the hack site. (Wild falcons fledging from nest sites in the wild also become independent of their parents in about six weeks time.)

Peregrine falcon release sites are often located at or near historic peregrine falcon nesting territories. Young peregrines normally disperse between 50 to 300 miles from their nest or hack site to their eventual nesting location, with females often dispersing further than males.

We also used the technique of hacking to release Harris's hawks, aplomado falcons, bald eagles, and elf owls in their respective native habitats.