SEALANT, WATERPROOFING & RESTORATION INSTITUTE SPRING 2017 39.2 PEREGRINE FALCONS: DIS RAPTORS OF WORK AT HEIGHT
COVER STORY PEREGRINE FALCONS: DIS RAPTORS OF WORK AT HEIGHT By Kelly Streeter, P.E., Partner, Vertical Access LLC In the course of a typical conversation about the dangers of my chosen profession as an industrial rope access technician, a common assumption is that my colleagues and I are not afraid of heights. To the contrary, I reply, we have a healthy fear of heights. But really, one of the biggest concern is not the heights. The heights are a known; we spend much of our time training to analyze, understand and mitigate those risks. The significant risks to our employees are those that we don t anticipate and plan for and one of these is working on a building where there are nesting raptors. Awareness of peregrine pairs on job sites is now part of our safety planning and project consultations with clients. In 1970, peregrine falcons in North America were listed as endangered by the U.S. Fish and Wildlife Service primarily as a result of pesticide contamination (mainly DDT). Once DDT was banned, reproductive success improved, and populations began increasing; however, the Eastern population had become extinct. During the 1970s, 2 39.2 SPRING 2017
Historically, peregrine falcons nested along cliffs and river bluffs but more and more have found urban areas attractive for nesting. Large urban and industrial areas have an abundant prey base, a lack of great horned owls, and tall buildings which mimic cliff faces and offer relative solitude far above the streets. programs were begun to restore peregrine populations by releasing young captive-bred birds. These breeding and reintroduction programs have been extremely successful, and many major cities across the United States and Canada host multiple breeding pairs. Peregrine falcons have made an incredible rebound and are now regularly seen in many large cities and coastal areas. In 1999 the peregrine falcon was removed from the federal endangered species list. It continues to be protected under the federal Migratory Bird Treaty Act and is still listed as special concern in many states; only Arizona and Colorado have listed the species as recovered. Historically, peregrine falcons nested along cliffs and river bluffs but more and more have found urban areas attractive for nesting. Large urban and industrial areas have an abundant prey base, a lack of great horned owls, and tall buildings which mimic cliff faces and offer relative solitude far above the streets. The birds make their nests on cliff-like ledges on tall buildings and prey upon pigeons, seagulls, and other urban birds. After a recent experience at a job site we were beginning to wonder if they were starting to prey on humans! Peregrine falcons can see prey up to two miles away - and when locked upon their prey, they dive at terminal velocity. There s no faster bird on the planet than a peregrine: they have been clocked at 242 miles an hour. Highly territorial, there will only be a few nesting pairs in any urban setting. The parents are fiercely protective of their nests and once the fledglings start to venture out, workers on tall buildings have learned to watch their backs (and their hats). Adult WWW.SWRIONLINE.ORG 3
birds are 15 to 20 inches tall, with females about one-fourth to one-third larger than males, and can pack quite a punch as they move in to protect their fledglings. Peregrines are relatively free of the stress from predators, except for the great horned owl (and urban dangers such as automobiles). These powerful birds of prey have managed to kill raptors as large as golden eagles and bald eagles (also potential predators) while defending their young; it has become clear that they are not afraid of us simple humans. Peregrines nest starting in March, and the chicks leave in about late May, which unfortunately coincides with the ramping up of field work for those of us who work on buildings in the northeast. Instead of a traditional bird s nest, peregrine falcons create a scrape, or shallow hollow in gravel, or dead vegetation on the ledge of a cliff or building and the eggs are laid there. In urban areas, peregrines have nested on the ledges of buildings, under bridges and in recesses under raised roadways. If a nest box is provided on a building roof, the peregrines will use it. Nest sites are generally reused every year. The female typically 4 39.2 SPRING 2017
lays three to four eggs and provides most of the incubation. The male brings food to her and also relieves her for short periods of time. Incubation takes 33 days. At about 9-12 weeks of age, the young fledge and begin to move further out of their parents territory until their parents finally chase them away. On a recent facade inspection project in Detroit, we became acquainted with Horus and Mystique, a nesting pair of falcons, while they defended their fledgling from our intrusion upon their turf. As soon as we got on rope and started descending down the exterior of the building, the adult birds took turns diving at us, hitting my helmet two or three times (we were told that one of them had previously flown off with another worker s hat). It was frightening, and it became impossible to focus on the work at hand. We had no choice but to cut the project short; I quickly descended to the ground while my colleague radioed for building staff to open a 19th floor window so that she could climb inside. Thankfully, helmets are part of our personal protection equipment for working on rope, and through our existing site safety protocols - specifically, radio communication with each other and with building staff - we were able to quickly demobilize and let the birds get back to their flying lessons. We ve seen peregrines many times before, often working around nest locations in order to avoid bothering them. But after our close encounter in Detroit, we have begun to start asking clients and building managers not only whether there are falcons nearby, but also whether any fledglings have left the nest. You can follow up on Horus and Mystique, along with other Detroitarea falcons, at the Peregrine Falcons Southeast Michigan FaceBook page. About the Author Kelly Streeter, P.E. is a partner in Vertical Access LLC in Guilford, CT. She can be contacted at kelly@verticalaccess.com. WWW.SWRIONLINE.ORG 5