Flight is instinctive, but skill is learned. At Great Spirit Bluff, peregrine falcon fledglings Thomas, Jaycie, and Kami are learning to hit moving targets in high-speed dives, turn and brake sharply in pursuit flights, and build muscle as they play and pursue one another, small birds, and Newman through the sky. In Falcon, Helen McDonald writes that falcons are playful in the nest, grabbing sticks, stones, and feathers in their feet, turning their heads upside down to watch buzzing flies and distant birds, and pulling on the wings and tails of their irritated siblings. Their playfulness and sibling bonds will serve them well as they practice their signature moves and build muscle and skill prior to dispersing in September.
High performance flight
Picture a young pilot stepping into a high-performance fighter jet for the first time. A falcon’s body is heavy in relation to its wing area and its flight profile, like the pilot’s jet, is anhedral – an unstable, upside-down Ʌ that gives falcons and fighters very nimble flight characteristics but also makes flight more challenging. The three siblings’ high-aspect wings are longer, thinner, and very maneuverable: suitable for active, flapping flight and fast gliding as opposed to the broad-winged, low-speed soaring of a turkey vulture.
Fortunately, juvenile falcons have longer tails and broader wings than adults – ‘training wings’ that are less maneuverable but a little easier to control as the fledglings learn to fly. Their high-speed sensory and nervous systems give them extremely fast reaction times and their world moves about ten times faster than the pilot’s world. A pilot’s formal training takes years. Thomas, Jaycie, and Kami have about two months.
High Gs and flight configuration
At the beginning of the video, we see one of the falcons pull up very sharply as it approaches the cliff. G-force measures the force of gravity or acceleration on a body. How many Gs does a falcon experience as it pulls up from a steep dive? Vance Tucker, a biologist at Duke University in North Carolina, attached an accelerometer to trained falcons. Our jet fighter pilot might lose consciousness at about six Gs. Tucker’s falcons pulled up out of dives at 25Gs. At this G-loading, a two-pound falcon weighs over 60 pounds.
A peregrine falcon needs to handle phenomenal stresses as it turns and maneuvers nimbly under high loads. How can a bird laboring under 25Gs pull up quickly from a dive? Its narrow, pointed wings are subject to fewer stressors than broad wings, its massive keel supports more flight muscle, its flight muscles are larger than those of similarly-sized birds, and it has exceptional control over the fine muscles in its wings and tail, so it can change its wing shape and aerodynamic properties in the blink of a peregrine’s eye. An extra pair of bones at the base of its tail help it turn and brake sharply in pursuit flights. Helen McDonald describes a falcon as a pair of eyes set in a well-armed, perfectly engineered airframe. After not much more than a week on the wing, the sibling squadron is rivaling the Blue Angels. It will soon exceed them!
Dispersal generally occurs four to six weeks after fledge and, much like fledge, is a process. Thomas, Kami, and Jaycie will wander further as their flight skills improve. We could see them on the flyway or in La Crosse. Will they interact with the US Bank juveniles? Adults are notoriously territorial on their breeding territories, but brown and cream juveniles are generally allowed to wander unbothered through adult territories in the post-fledging and dispersal periods. We’d love to hear of any encounters in La Crosse and encourage people to report band numbers to reportband.gov and eBird. The more you share, the more we know!
To watch the sibling squadron live, go to https://www.raptorresource.org/birdcams/gsb-falcons/. They tend to be most active in the morning and evenings.
June 25, 2023: P/59 gets a meal from Newman. P/60 steals, mantles & keeps it – https://youtu.be/XVJ_AdwPl-s. The video opens with Newman flying out from low on the cliff. He circles back to deliver a meal to P/59, who is waiting on the cedar snag. She struggles with the unwieldy prey, but manages to fly it into the rock ledge diner. Unfortunately, she doesn’t keep it. P/60 flies in at 3:37 and captures it after a brief tug-o-prey! She mantles over it and lets her sister know that she intends to keep it!
June 23, 2023: Sokol wedrony – posilające się i odpoczywające młode na budce (feeding and resting chicks on the nestbox) – https://youtu.be/BUfgSv4h6y4. A nice look at the sibling squadron at rest. Note the differences in plumage between the young and adults. Falcons molt into adult plumage at two years of age…something we discussed in this blog: https://www.raptorresource.org/2021/03/24/how-do-we-know-falcon-zooeys-age/.
June 22, 2023: Flight training plus alert – https://youtu.be/pgo8AFcuvY4. The sibling squadron levels up! I especially enjoyed watching the chasing and action after about 1:48. Don’t miss the pull up starting at about 2:25. You see a falcon come in from the left at about 2:25. It flies toward the camera and flares up at about 2:27, giving us a nice look at falcon flight techniques! Slow it down if you want to see the details – but you’ll still need to look quickly!
Links and resources