Peregrine and Parenthood

Peregrines and Parenthood

By Ron Joseph, Wildlife Biologist, U.S. Fish and Wildlife

“How very exciting and quite a relief”: a blogger’s response to Patrick’s announcement of a falcon hatchling summarized our collective feelings. I couldn’t have stated it better myself. Admittedly, as the days dragged past a projected first hatch date, I had my doubts that any eggs had survived the cold snap that coincided with egg laying more than a month ago. Trying times are still ahead for this youngster and any sibling(s) that may hatch over the next few days (don’t be surprised if an egg or two doesn’t hatch). As my father was fond of saying, “They’re not out of the woods yet.” But there is reason for optimism. Peregrines are very dedicated parents so we’ll see food deliveries increase especially as the young mature. The adult male has been busy off camera caching food in “cupboards” such as crevices or ledges on old buildings or bridges. Those prey items will be retrieved and delivered to the attending adult. She’ll tear meat from a bird (most likely killed on the wing) before feeding it to her young. Since the young will be nearly full grown when they fledge in six weeks (six plus a few days for females), you can imagine how much food will be delivered by both parents.

At one month old, the young will compete with each other for food delivered by their parents. The nestlings will aggressively strike at food with their talons. It’s during this stage of their young’s development that parents, not wanting to be “footed” by a hungry youngster’s sharp talons, will drop food off quickly before departing the nest box. Some young are reluctant to leave the comfort of the eyrie when it’s time to fledge (sounds like my 19-year old son!). I once watched an adult female peregrine in Bryce Canyon National Park fly close to her eyrie clutching a dead white-throated swift in an attempt to encourage one reluctant youngster to fledge. It was actually quite entertaining. The youngster’s siblings had already fledged. But this particular youngster had no intention of leaving the red sandstone cliff eyrie. Each time a parent flew close by carrying food, the youngster would open its wings and scream defiantly. Finally, as the nestling leaned forward again with open wings, a strong gust of wind lifted it sideways out of the nest. The fledgling soon discovered the value of wings as it awkwardly chased its parents. The adult female dropped the dead swift and the youngster caught it in mid-air.

Peregrines in Maine also prefer to catch birds on the wing. Experienced adults use the sun to their advantage during hunting forays. They “climb” high in the sky, positioning themselves between the sun and their targeted prey knowing full well that an unsuspecting blue jay, for example, won’t look up into the sun where the peregrine is making its stoop. Peregrines fly over 100 mph (and sometimes much more) in a dive; their talons form a loose fist until the moment they strike. When peregrines hit their prey, be it blue-winged teal or grackle, the feathers fly as the injured bird tumbles through the air.

I collected feathers from over a dozen different bird species (i.e. rose-breasted grosbeak, northern flicker, mourning dove, American robin, to name a few) in one western Maine eyrie in the mid-90s. The Maine Dept. of Inland Fisheries and Wildlife sent the feathers to the late Roxie Laybourne of the Smithsonian Institute for identification. She was the world’s leading expert on bird identification from forensic evidence. I was privileged to work with Ms. Laybourne when I worked as a raptor biologist in Utah. She helped me identify lots of prey remains from many peregrine eyries. She could identify the age and sex of a bird based on one feather. Ms. Laybourne told me once that she helped the FBI solve a murder by matching the pillow feathers in a dead man’s nose with the pillow used by the murderer!

If all goes well in the weeks ahead, the young peregrine(s) should fledge sometime in mid-June. The nest box will become littered with small feathers, desiccated prey bones, and lots of white wash (falcon excrement). Be sure to turn on the volume because nestlings are quite vocal, especially when food is delivered.

Ron Joseph
Wildlife Biologist