Pitt's Peregrine Paterfamilias Presumed Departed, New Male Falcon Thought to Control Cathedral of Learning Nest

PITTSBURGH—Observers of the peregrine falcons nesting on the 40th floor of the University of Pittsburgh's Cathedral of Learning suspect that another male falcon has replaced longtime patriarch, Erie. The presumed new bird's identity is unknown, but photographs and the suspect male's behavior suggest that he is not Erie, who has raised 22 chicks with the female Dorothy since they occupied the nest in 2002. Because Dorothy has laid her eggs for this year, the falcons' caretakers cannot safely access the nest to confirm the new bird's identity.

Although Erie's fate remains a mystery, observers suppose that the new male did not violently overthrow the nest, which could provide significant clues about the turnover of peregrine falcon nests, said Tony Bledsoe, a lecturer of biological sciences in Pitt's School of Arts and Sciences who helps monitor the falcons. Nests often change control when a young peregrine falcon (male or female) defeats an older bird. Last year, Erie decapitated a younger male from the Cleveland area that attempted to claim the nest and Erie's female companion, Dorothy.

In the case of this new male, observers on the ground noted that only Dorothy was present throughout October of last year. The supposed new male arrived in mid- to late-November. Todd Katzner, a Pitt adjunct professor of biological sciences and the National Aviary's director of conservation and field research, said that falcons stay in their home territory year-round. It is unlikely that Erie would remain absent for a long period of time then suddenly reappear, particularly when the nest has been a successful breeding ground. Therefore, Bledsoe said, Dorothy's prolonged solitude and the new male's sudden presence suggest that he did not seize the Cathedral nest—he found it.

"We have examples of nest takeovers, but this appears to have been a case of an individual leaving or, most likely, dying and another taking his place," Bledsoe said. "It's a single example, but a contribution to the developing story of how peregrine's interact and establish pair bonds. Also, the new bird, depending on where he is from, could provide an idea of the patterns peregrine falcons follow when breeding and seeking nests."

Nest turnovers also can aid in conservation efforts, Katzner said. When fallen or missing mates are replaced (or not replaced), that can help researchers estimate a species' mortality rate and overall population.

Kate St. John, a volunteer for the National Aviary who monitors and maintains a blog about the Pitt falcons, first suspected that Erie was no more. She noticed in February that the male falcon's ankle bands—used to track and identify the birds—were of different colors than those Erie wore. She spent six weeks comparing 4,500 photos of Erie and the suspect male. She noticed not only a difference in the bands but in the color and pattern of the birds' feathers.

These observations corresponded with the male falcon's overly enthusiastic courting behavior in November, which was unusual for Erie in his later years, St. John said: "Erie was excited his first year, but later on he was ho-hum. Actually, that's how we knew he won the fight last year—everything was business as usual between him and Dorothy."

At nine-years-old, Erie was in the twilight of a busy life that no doubt weakened him, Bledsoe said. During breeding season, he would hunt to win Dorothy's favor with fresh prey; he fed her as the eggs developed inside her; and, once the eggs hatched, Erie provided for himself, Dorothy, and the chicks. For at least 50 days out of the year, year after year, he hunted for as many as six mouths, Bledsoe said.

"It was not an insignificant job to be Erie," he said. "I suspect that Erie took a big hit last breeding season when he fought off a rival then raised four more young. His chances of surviving into another breeding season were probably significantly lowered."

For more information, visit St. John's blog, "Outside My Window," at www.wqed.org/birdblog/2008/04/02/who-is-he-new-male-peregrine-at-univ-of...

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4/4/08/amm