RiverQuestion of the Month
for April 2008
In 1991, a pair of peregrine falcons began nesting at the Gulf Building in downtown Pittsburgh, and "nesting pairs" crop up in the local news from time to time, on buildings or bridges. Though peregrines were removed from the federal endangered species list in the late 1990s, they are still listed as an endangered species by the Commonwealth of Pennsylvania.
Are there still nesting pairs of pergrine falcons along the rivers in Pittsburgh?
Yes. There are four nesting pairs of peregrine falcons in the Pittsburgh area. They are the only confirmed nesting pairs in Western Pennsylvania. Two pairs live on buildings in nest boxes constructed by local conversation agencies and two pairs were recently found nesting on local bridges.
Historically, peregrine falcons were one of the most widespread birds in the world. In the early 1900s there were approximately 350 nesting pairs of peregrines east of the Mississippi River. By 1965, there were no successful pairs in that same area. The drastic decline of peregrines in the United States and worldwide was attributed primarily to the use of pesticides, including DDT. The pesticides caused the females to produce eggs with thin eggshells. The eggs could not tolerate the weight of the nesting parents and were crushed. The banning of DDT in the U.S., combined with re-introduction efforts, has allowed a gradual increase in peregrines here. However, DDT is still legal in other countries and affects the population worldwide. Peregrine falcons were removed from the federal endangered species list in 1999. They are still listed as endangered in Pennsylvania.
The peregrine falcon’s natural nesting preference is on cliffs overlooking river systems. In 2003, two cliffside nesting sites were discovered in Pennsylvania, the first in close to 50 years. When their natural habitat is unavailable peregrines settle for the next best things, skyscrapers and bridges. Peregrines mainly subsist on other birds taken in flight. Pittsburgh’s peregrines eat pigeons, other urban birds and water fowl, including ducks. (One of their nicknames is “duck hawk.”)
The recent history of peregrine falcons in the Pittsburgh area is ripe for depiction in a Hollywood movie. Territorial fights, chase scenes, hit-and-runs, beheadings, electrocutions, mid-air mating, being replaced by a younger mate and finding an imposter’s eggs at their nest nesting site are all par for the course in the lives of urban peregrines.
In 1991, a pair of peregrine falcons began nesting at the Gulf Building in
downtown Pittsburgh. The current adult male began nesting at the site after killing the pioneer male in 2003. Since 1991, 59 chicks have hatched at the nest. Four eggs were laid at the end of March 2008, and are expected to hatch in April or May.
Peregrine falcons began hatching from a nest on the University of Pittsburgh's 42-story Cathedral of Learning in 2002. A widely publicized territorial fight between two male peregrines occurred in March of 2007. The incumbent male won the fight and remained at the nest only to be replaced by yet another male last fall. The original pair produced twenty-two offspring, including the adult male currently nesting at the Gulf Building. A new male and the original female are currently incubating four more eggs.
In the spring of last year, nesting peregrines were spotted on two local bridges. A pair of peregrines nesting on a Beaver County bridge over the Ohio River produced 2 chicks in 2007. It is possible that the pair had been nesting there for several years before being discovered. A nesting pair was also found on an Allegheny River Bridge in Allegheny County last year, but no viable eggs were produced. Earlier this year a nesting box was established on the site in hopes that the pair will return and have a successful hatch.
A streaming video feed of the Cathedral of Learning nest and an image of the Gulf Building nest, refreshed every 15 seconds, are available at http://www.aviary.org/csrv/webcam.php.