Bird Calendars

NOTES FROM NATURE

By Jerry Toll

Peregrine Falcons: An Update on the Midwest Restoration Effort

Over the years, ASO has been involved in many successful conservation efforts. The preservation of Jensen Prairie and Heron Haven, the effort to restore and preserve the Platte and Niobrara Rivers, environmental education and being legislative watchdogs are just a few of the myriad ways that have consumed ASO's time and passion over the years.

Another program was the release of Peregrine Falcon chicks from the Woodmen Tower in downtown Omaha. ASO members, acting as surrogate parents, volunteered hundreds of hours between 1988-1990 observing the fledglings take their first tentative flights into the dangerous world of adulthood.

When the last chick was fledged, ASO's involvement ceased, but the success of the effort continues to this day. Every year since, a Peregrine has tried to nest on the Woodmen Building. The number of young successfully fledged through the years varied, as can be expected when you are dealing with wildlife.

According to Tim Sauter, who continues to monitor the Peregrines for the Woodmen Building, of the 31 eggs hatched, 19 have survived to fledge. Each young produced went into the pool of the Midwest population. On August 25, 1999, Peregrines were removed from the Endangered Species List. This year Zeus and Amelia produced three young after having stayed all winter.

The Midwest effort to restore the Peregrine Falcon population was led by a team at the University of Minnesota School of Veterinary Science. Dr. Pat Redig developed the recovery plan and initiated it. Peregrines historically nested in the Upper Midwest at cliff sites. Early attempts at releasing birds (hacking) at these sites were unsuccessful along the lowland river sites of the Mississippi River.

However, since 1988, hacking attempts along the shore of Lake Superior were successful. The young Peregrines encountered overwhelming predation from Great Horned Owls and other predators. Meanwhile, Cornell University was demonstrating that young could be successfully hacked from urban skyscrapers and bridges, and the Midwest effort shifted in large part to urban releases.

It proved very successful. It was easy to find the people and the money to bring an endangered and charismatic species recovery to cities all across the eight-state region of the Upper Midwest. Predation on the inexperienced fledglings was virtually nonexistent. There was a ready source of prey species in the form of city birds, although this was not the case in Omaha where migrant Yellow-billed Cuckoos were preferred.

Finding enough young to meet the demands of the recovery schedule fell to falconry breeders. To find and breed enough Peregrines successfully when the species was virtually extirpated from eastern North America proved a daunting task. The decision was made early that enough pure anatoms, the subspecies of the eastern U.S, could not be found. Therefore, lineages from seven subspecies were included to a lesser degree.
The Midwest recovery effort came under criticism for this action, because all of the other eastern releases were using only anatums. The concern was that using other subspecies would adversely affect the long-term survival of the population. In their recently published paper, Bud Tordoff and Pat Redig state this was not the case.

There was no substantial difference in the adaptability of five of the seven surviving mixed subspecies that subsequently bred.

When the decision was made to begin urban release, no one wanted cities to be the permanent home of the Peregrine in the Midwest. It was hoped that eventually Peregrines would find a way to reclaim their historical cliff nesting sites in the Upper Midwest. That hope eluded the recovery plan until this year when, after a forty-year absence, Peregrines finally returned to nest at cliff sites along the Upper Mississippi.

Three factors, it seems, finally came together to make it happen. The Peregrine population continues to grow in the region. This led to fewer suitable breeding sites being available, forcing them out of the cities and onto the cliffs. The increased presence of adult Peregrines along the river over the last decade has challenged the dominance of Great Horned Owls, educating them to the need for coexistence.

The removal from the Endangered Species List was the result of a concerted, dedicated effort by many agencies, organizations, and individuals who pulled together to make it happen. The Endangered Species Act requires that any species delisted should continue to be monitored to insure recovery. The proposed Peregrine monitoring will consist of five surveys of 20% of the population every three years.

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