Peregrine Falcon Recovery

Abstract

In 1970 The Peregrine Fund began a long-term research program at Cornell University to learn how to propagate Peregrines and other rare falcons, in hope that eventually the progeny could be used to bolster the remnant wild populations in the West and to restore the species to its vacated breeding range in the East. Today The Peregrine Fund program has breeding lofts located not only in Ithaca, N. Y., but also in Wyoming, Colorado, and New Mexico, with total capacity for housing about 80 pairs of falcons. We currently have more than 130 Peregrines in these facilities, including both wild-caught and captive-produced individuals. We produced our first 20 Peregrines at Cornell in 1973, and since then have raised a total of 434 young from 46 females through the

1979 breeding season. More than 100 of these youngsters came from just three exceptionally productive pairs.

We have now introduced 341 young Peregrines into the wild by hacking, fostering to wild Peregrine parents, and by cross-fostering to Prairie Falcons in 16 states: California, Colorado, Idaho, Maryland, Massachusetts, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Pennsylvania, South Dakota, Utah, Virginia, Vermont, and Wisconsin. Experimental work on the release and establishment of captive produced Peregrines by hacking began in a small way in 1974, expanded significantly in 1975, and continued to increase in scope through 1979. Hacking is a process whereby the young birds are brought into

the wild one week before fledging. They are handfed at the hacking station and then gradually weaned to taking birds on their own for food.

If we can continue on our present course, the next five years will certainly see the establishment of some breeding pairs of Peregrines in the eastern United States and an increase in the number of productive eyries in the West. Success in these efforts will depend upon the cooperation of many diverse groups and individuals that have a concern for the recovery of the Peregrine.

This year in our propagation efforts we broke the 100 mark in the number of young peregrines raised in our combined programs at Fort Collins and Cornell - 110 young came from eggs laid in captivity and 19 from wild eggs hatched in our incubators.

At Cornell 21 females laid a total of 177· eggs, of which 136 could have been fertilized; 107 eggs were actually fertile, 71 of them hatched (66%), and 57 hatchlings survived to achieve full development. The comparable figures for Fort Collins are: 24 egg-laying females, a total of 139 eggs laid, 80thathadachanceoffertilization, 75 fertile, 58 (77%) hatched, and 53 young raised. Twelve new females laid eggs for the first time. An additional three were produced in Wyoming and New Mexico.

Release work in the East started early this year with the fostering of young to Baltimore's Scarlett in early May. Field operations continued from there through six states from Virginia to New Hampshire with a final shut down of the last site in New York during the first week of September. Fifty-seven young were put out into the field in the east, only twelve (21 OJo) were lost, making this the lowest mortality suffered thus far.

As ironic as it sounds, success itself has caused some problems. Returning Peregrines from seasons past set up territories around their former hack sites. Some tolerate the hacked fledglings and join in eating the food which is provided, but others aggressively chase the juveniles. Such aggression can be challenging for a youngster during its maiden flight, and two fledglings were chased off beyond tracking range and were lost before they could learn their way back.

Western workers released peregrines in six states. In addition to Colorado, New Mexico, and Idaho where we have ongoing projects, we extended our activities into Utah, Nebraska, and South Dakota. Fifty-seven young were released by one of the three methods. Twenty-five young were fostered into wild peregrine nests, but only 12 (48%) survived to fly from the eyries. Seventeen nestlings were cross-

fostered to nesting pairs of prairie falcons; only 5 (29%) survived. Fifteen young were hacked at cliffs or at a tower, and 14 (93 OJo) survived to 'the stage of independent hunters. Natural predators - golden eagles and great horned owls - accounted for most of the losses, which were unusually high by comparison with previous years,

Each year lone Peregrines surviving from previous years return to some of the release sites. This year, in addition to the four pairs off alcons that occupied sites in the east, eight individual Peregrines were present at other eastern locales, and one falcon returned to a new western hacking location in Colorado. As many as six falcons may have to be released by hacking in order to produce one returnee; therefore these lone, returning falcons represent a great deal of laboratory and field work, as well as a long but successful run through the gauntlet of natural selection.

This spring, for the first time in more than 20 years, Peregrine Falcons paired, mated, and laid eggs at eyries in the eastern United States. Last year we had the formation of a pair of released Peregrines at a site in the New Jersey wetlands in midsummer, after the normal mating season; and we also had Scarlett, the female that had taken up a permanent territory in downtown Baltimore, where she established her eyrie on the ledge at the 33rd floor level of the USF&G home office building. All through the winter we waited to see what these falcons would do in 1979. As March, the normal time for pairing, passed, no falcons had taken up residence at the New Jersey towers, and no mate had appeared in Baltimore for Scarlett. We began to fear there would be no breeding by our released falcons again in 1979.

We decided to try to provide a male for Scarlett, for she indicated by her nestscraping behavior and other signs that she would soon come into breeding con-

dition. On a building across the street, a flat roof offered a convenient location within Scarlett's daily view to set up a cage for housing a prospective mate. By the middle of March the cage had been constructed, and on the 19th we placed an l l-year-old, falconry trained tiercel named Blue Meanie inside. Our attendant began began a daily vigil of care and observations that lasted well into June. The idea was to see whether the two birds would establish a pair-bond while the Blue Meanie was confined, so that on release, he would be attracted to Scarlett and would remain in the city as her mate. Scarlett very quickly discovered the tiercel in his cage and made frequent visits to him to take the quail and pigeons the attendant left as an enticement on an outside shelf. Scarlett showed much interest in the Blue Meanie, calling and wailing to him. Once he offered her a quail through the bars, but otherwise he did not return her favors.

On April 4 Scarlett laid the first Peregrine egg to be seen in the outdoors east of the Mississippi River in more than 20 years. On April 7 she laid a second egg, and we knew that if our plan was to have any chance for success, we would have to set the Blue Meanie free before Scarlett completed her clutch and began steady incubation. Released from the cage, he flew up and at once joined Scarlett in the air; soaring together wing tip to wing tip, they disappeared around the other side of the building. Our hope began to rise with them, but in about ten minutes Scarlett reappeared alone. The Blue Meanie was gone and never seen again! A second, captive produced tiercel released later in the season was also unsuccessful. Meanwhile, Scarlett laid her third and final egg and began incubation.

After allowing Scarlett to incubate full term, we substituted some downy young falcons from Cornell for her to mother. She performed her parental duties well, catching much of the food for the nestlings herself, and she successfully fledged two males and two females. Thanks to a sympathetic press and to the informed and tolerant citizens of Baltimore, Scarlett has already become one of the most famous Peregrines in history, rivaling her Canadian counterpart, the Sun Life Falcon of Montreal.