PEREGRINE FALCONS AT CRATER LAKE -- a rare and beautiful sight for those lucky enough to catch a glimpse of this magnificent bird.

The peregrine falcon is a crow-sized bird of prey that feeds primarily upon smaller, air-borne birds. Historically peregrine falcons were found throughout the world. Concern began to develop in the early 1950's, as bird lovers and biologists alike began to notice the disappearance of the peregrine.

The rapid decline was due to the pesticide DDT, and its metabolite DDE. Peregrines acquired the pesticide through consumption of other birds already contaminated by DDT. Over time, increasingly higher concentrations of the pesticide accumulated in the fatty tissues of the falcons, altering the female peregrine's ability to deposit calcium in the eggshells. As a result, the thin shelled eggs were often broken or crushed by the incubating falcons, and populations began to decline worldwide.

The use of DDT was banned nationwide in 1972, yet mortality due to eggshell thinning and breakage remains a persistent problem. This is because DDT remains in the ecosystem long after it has been applied. In addition, peregrines ingest prey species contaminated with DDT that migrate up to the United States from Latin American countries, where DDT is still used.

CRATER LAKE NATIONAL PARK was, until recently, the only known active historic peregrine falcon nest site in all of Oregon; now it is one of two. In the 1930's there were 39 known active nest sites in Oregon.

Peregrines have been observed at Crater Lake from the late 1800's to the present, and nest sites have been noted in park records. There was a great deal of excitement in 1979 when a pair of peregrines were observed, and their nest site was located and found to contain two young. It was later discovered that the pair had produced a total of three eggs, one of which failed to hatch.

In 1980, this nest was found to be occupied, but all eggs failed to hatch. These eggs were collected, analyzed, and found to have excessively thin shells due to pesticide contamination, causing the eggs to fail to hatch.

The park staff met with the Oregon Department of Fish and Wildlife and the U.S. Fish and Wildlife Service and agreed that the park, in cooperation with the State of Oregon, would begin an active manipulation program.

In 1981, the park began manipulating the nest site with the assistance of the Predatory Bird Research Group (PBRG), Santa Cruz, California, through a technique known as direct fostering. This is the process whereby peregrine eggs are pulled from the nest shortly after the onset of incubation, and replaced temporarily with ceramic, dummy eggs for the duration of incubation; these dummy eggs are then removed and replaced with chicks. Sometimes, chicks are fostered into the nest at the time the initial eggs are removed. Surprisingly, the adult peregrines quickly accept dummy eggs, and continue to incubate them as if they were their own. The parents also readily accept chicks, whether added at the onset or end of incubation. Meanwhile, the thin-shelled peregrine eggs are artificially incubated at the PBRG facility under controlled laboratory conditions; surviving chicks are later fostered into wild nests. In 1982, the nest site manipulation was repeated successfully.

In 1983, no viable eggs were produced at the nest. As a result, an alternative plan to direct fostering known as hacking was employed. This is the process whereby peregrine chicks can be raised to independence without the presence of adult peregrines. It involves the placement of a "hack box" atop a cliff or tower, in suitable peregrine falcon habitat; during the summer months, chicks are placed in the box, observed and fed by the two PBRG hack site attendants.

After one week in the box, the chicks are ready to take their first flight, and the front of the box is removed. The final six weeks of the operation involve daily feeding, 24-hour monitoring, and constant protection of each falcon from progressive predators, such as golden eagles and great horned owls.

In 1983, 1984 and 1985 three peregrines were successfully released each year in Crater Lake through hacking.

In 1986, two courting peregrine falcons occupied the nest but the female was too young to produce eggs. Three peregrines were released during the summertime hacking operation. Unfortunately, only one survived to reach independence, the other two were lost to predators. Despite these losses, biologists at Crater Lake National Park feel the overall hacking operation has been a success: in four years of hacking ten peregrines have been successful released.

It is believed the same courting pair from 1986 returned again in 1987 to nest. The female successfully laid four eggs. The park, with the assistance of PBRG and the Oregon Department of Fish and Wildlife, conducted a site manipulation using the technique of direct fostering as in 1981 and 1982. Four eggs were removed from the nest and sent to PBRG, of which three hatched and were fledged in California. They were used in other wild nest sites, other than the park's, for similar nest manipulations. Two other captive bred young were then fostered into the Crater lake eyrie. The parents readily accepted the chicks. Unfortunately, about the time the chicks were fledging (leaving the nest) one of the young was killed, possibly by a great horned owl.

In 1988 the peregrines again used the historic eyrie and laid four eggs, of which three hatched. Approximately twelve days later all of the young and the adult female were killed, again, possibly by great horned owl. In order to ensure the successful fledging of peregrines in the Crater Lake area it was decided to cross-foster young peregrines into a nearby prairie falcon (Falco mexicanus) nest. The prairie falcons successfully fledged two peregrines in this effort.

In 1989 and 1990 it is believed that the male returned with an immature female. However, inclement weather, lack of funds and logistical problems limited monitoring efforts in 1990. In 1991 the historic eyrie again became active. The male was identified as a previously captured wild bird. This pair was successful in fledging three young without any human manipulation.

Although the hatching success in recent years has been good, analysis of the eggs shows significant thinning and that the female has been subjected to pesticide contamination.

The successful fledging of three young in 1991 was very promising and was the result of many years of effort and patience. Continued nesting success at the same eyrie resulted in additional steps to monitor and evaluate the effects of predation on the peregrines.

The summer of 1993 also brought success to a pair of peregrine falcons (Falco peregrinus) nesting within the park. The nest site was monitored throughout the spring and summer months and the pair fledged two young in late July. This site is one of only thirteen in Oregon that successfully produced young in 1992.

Peregrine falcons are currently listed as endangered under the Endangered Species Act. Extensive use of DDT in this country through the 1960's and early 1970's has resulted in egg shell thinning and dehydration leading to a decline in peregrine reproduction.

The eggshells from the 1991 and 1992 Crater Lake hatchlings were collected for analysis for the recurring evidence and damage of DDT. Although the years 1991-1993 have been successful for the peregrines at Crater Lake, other areas were not as fortunate. Until there is a world-wide ban of the detrimental pesticide, the continued existence of the peregrine falcon will remain uncertain.

The peregrine falcons at Crater Lake illustrate how National Parks have become islands in our modern world. The success of preserving wildlife and ecosystems depends not only on what we do within the boundaries of this park, but how humankind conducts itself on this planet. With a little luck and a pair of binoculars, you may have the good fortune to catch a glimpse of this rare and beautiful bird during your spring or summertime visit to Crater Lake National Park.