PARK E-VENTURESYoung Raptors Launch into Life
June through August is baby season for birds of prey in the Golden Gate National Parks. Many of our local raptors are stick nesters: Red-tailed and Red-shouldered Hawks, Cooper’s Hawks, Great Horned Owls, White-tailed Kites, and Osprey. And “fledging” doesn’t have the same meaning for these species as it does for a quickly departing young American Robin or Chestnut-backed Chickadee. Raptor fledging is more of a process, called “branching,” and it may take days or weeks to transpire. What exactly is branching? As many of these mid-sized birds of prey reach their 4th or 5th week after hatching, they are full-size and fully-feathered. Their white, downy wisps have become dark and smooth contour feathers. They have become aggressive sibling competitors for the morsels of food that the parent raptors drop in the nest. But then they start to get jumpy. They use the nest as a kind of springboard to practice leaping while flapping wildly—and for now, uselessly—in the air. This flight practice in the nest quickly evolves into short bursts of flight from the nest to a branch. And then to another branch. And another. And then to another tree. And then they sit. Sit. Sit. Sit. Sit. Beg for food. Sit. Then here comes mom with a prey delivery to the nest and—LEAP!—they scramble-fly-spring pell-mell back into the nest to get their fair share (and more) before their sibling can. Eventually the parents will use the prey deliveries to coax the kids right into the sky. It’s amazing what a little hunger and sibling rivalry can do. Branching and fledging aren’t always the lyrical events that I’ve described here. Young raptors are naïve raptors. Naïve raptors are themselves vulnerable to predation. Between begging calls and clumsy landings, young hawks are easily spotted by ravens and raccoons, by dogs and coyotes, by Great Horned Owls and humans. Yes, even well-meaning humans may whisk a young hawk or owl into a box and carry it to a rehabilitation center, thinking this is what’s best. Wildlife rehabbers know, however, that a young uninjured hawk has the best chance of being cared for successfully—even if grounded—by the parent birds on-site. Urban areas are especially tough on young raptors. In the Bay Area, GGRO volunteers have documented recently fledged Cooper’s Hawks killed by eating poisoned rats. We’ve picked up a young Red-tailed Hawk in the Presidio that had just been killed by a car. It had a gopher gripped in one sure foot, clearly the object of its attention. And we’ve helped retrieve an injured Peregrine Falcon, still reeling from an unbelievable impact with a plate glass window. For these new hawks and owls of the year, summer is clearly a dicey time. Just negotiating the process of learning how to hunt while avoiding becoming food themselves, these birds have their hands (talons?) quite full. So as you move through the parks this summer, try to be conscious of these young raptors, putting their new acts together. Don’t poison the rats. Take time to get out of your cars on a summer evening, and listen for the lovely “retch!” of a young Great Horned Owl, waiting for its share. Allen Fish (Photo of branching Red-shouldered Hawk by Don Moseman)
June E-ventures: Where are the raptors?
A common question I hear this time of year is: Where are the raptors? While Bay Area hawks may seem dormant during summer, most adult raptors are actually very busy and focused … on their nests. After nestling hawks have hatched locally in May and June, they are growing as rapidly as they ever will. They demand a steady stream of prey to support the growth of bones and muscles for flight, and for defense from predation. This means that while one parent keeps an eye on those downy chicks, the other parent is hustling food back to the nest. Cooper’s and Sharp-shinned Hawks have an interesting problem in this role, being largely “bird-eating” hawks. The small size of the males means that his prey deliveries to a nest of older chicks have to be fast and accurate drops, with very little slowing down. He is, after all, potential prey himself for his larger and likely hungry daughters. In the urban Bay Area, raptors such as Red-shouldered, Red-tailed, and Cooper’s hawks may nest within many city limits. Perhaps due to the height of the nest trees high above human activity on the ground, or the tolerance of the hawks to casual human traffic, these urban hawks do seem to nest and reproduce almost as well as their rural relatives. But urban areas do present some increased problems for hawks. Some are obvious, such as window collisions, rat poisons, electrocutions, and car-kills. Others are not as intuitively clear, like an increased exposure to diseases because of denser and less diverse prey populations. So, as you walk through Bay Area neighborhoods this summer, pay attention to the subtle noises of our tree-nesting raptors – begging calls from the chicks, contact calls from male to female and back. But also do what you can to support the hawks. For example, keep moving through. Give raptors some space to feed their young, to move in and out of the nest area without fear. Keep your bird feeders away from plate glass windows, and don’t use chemical rat poisons, which can be devastating secondary poisons to birds of prey. Allen Fish (Photo of adult Red-shouldered Hawk leaving nest by Don Moseman) |
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