Friday, October 4, 2013

Sharpies at Hawk Ridge (combined)

“Hold it like an ice cream cone,” instructed Gail Johnejack, Education Director at Hawk Ridge Bird Observatory, as she skillfully wrapped her hand around mine, and guided my fingers into a careful grip on feathers and legs. When she transferred the bird into my care, I could feel the heartbeat in my own skin. A breeze ruffled the sharp-shinned hawk’s feathers, and I imagine we were both eager for it to continue its long migration journey. Beyond the bird stretched the city of Duluth, and the shimmering water of Lake Superior.

Hawk Ridge in Duluth, MN, is one of the top five hawk migration sites in North America for overall numbers and diversity of species. Each fall, about 82,000 raptors pass through this bottleneck on their southern migration. Understandably reluctant to cross a large body of water, the birds funnel southwest along the shore of Lake Superior. The high, rocky outcrop of Hawk Ridge Nature Reserve makes a great viewing platform, and people come together from all over the country to watch the migration here.

It’s not easy, though, the migrants of are often tiny specks against the blue. Raptor biologists here have a special trick for getting close-up views of the hawks – bait. Using a technique a lot like fishing, researchers pull the string on a lure to make it look like an injured bird. When a raptor swoops down for an easy meal, it becomes tangled in one of a series of nets. Researchers carefully extricate it from the net, take a variety of measurements, and attach a numbered band to its leg. “Our utmost priority is to keep the raptors safe,” assured Gail. “When a raptor is captured for banding, it is held for a very short time, and then we let it get on its way.”

About three percent of birds banded here are recaptured. Based on the data collected from recapturing banded birds, sharp-shinned hawks migrating over Hawk Ridge generally head southeast to Illinois, and then southwest toward east Texas and Mexico, following the prevailing wind pattern.

Sometimes naturalists bring a recent captive down from the remote banding station so that folks on the overlook can get a better view. Moments after we arrived, two naturalists called everyone over to see a couple “sharpies” in hand. To prevent the hawks from hurting the humans or themselves, the naturalists held their wings, tail, and legs gently but firmly in the fist of one hand. The birds, both hatch-year females, looked quite calm.

Sharp-shinned hawks are the smallest hawks in North America, and have the biggest size difference between males and females. Females are up to one-third bigger than males, and this size difference means that they focus on different sizes of prey. Males tend to hunt smaller birds, such as sparrows, while females can concentrate on larger prey, like robins. This has two big advantages: males and females do not compete for the same food source, and chicks can get appropriately sized food as they grow.

During the first few weeks after hatching, the female sharp-shin broods the chicks while the male hunts and brings in small songbirds. He typically removes and eats the head before delivering the meal. As the chicks mature, the female joins in the hunting and brings larger prey for the hungry fledglings.

Sharp-shinned hawks are agile and acrobatic fliers, navigating dense woods at high speeds by using their long tail as a rudder. Short, rounded wings help them zip through tight spaces after small birds. During migration, they leave the dense forests of their northern nesting grounds and take to the open sky.

To help make the journey easier, these and other hawks will ride thermals, which are rising pockets of warmer air, formed by the uneven heating of the surface of the Earth. Thunderheads are visible thermals, where clouds of water droplets show just how high the warm air is climbing. When you see turkey vultures or other birds soaring in lazy circles without flapping, they are riding thermals.

For every mile a bird rises on this avian elevator, it can coast downwind seven miles without flapping. Still, sharp-shinned hawk’ migration from the top of this continent to the bottom takes strength, endurance, and stored energy. In order to be ready for the journey, these small hawks grow furiously—going from egg to adult size in just over 7 weeks.

I gripped the sharp-shinned hawk carefully, amazed at both its sturdiness in my hand, and also the strength I could sense in its muscles. Erik Bruhnke, Count Interpreter, positioned himself just over the cliff, camera in hand. All day, Erik alternates between spotting and identifying birds, answering visitors’ questions, and taking photos of hawk releases. He is a wealth of information.

“I watched birds all my life, but I’m not a bird watcher,” Harry a Hawk Ridge volunteer, says humbly. “I’m just trying to become one! One of the benefits of Hawk Ridge is that amateurs can really learn from all the real birders that are here.” Erik is equally thrilled the arrangement. “Teaching is the best way to learn. Working here really helps me learn about birds on a deeper level.”

Harry is retired, like many Hawk Ridge volunteers. He enjoys interacting with the other main type of volunteer—college students fulfilling requirements for courses.  Harry loves his job, because “volunteers and visitors both find commonality and community in the birds – they draw us all together as a group. It keeps me young!” says Harry.

The natural setting is also a bonus. Bright sunshine, a warm breeze, and a terrific view are a stunning combination. Even chilly gray days have their own beauty. Harry likes the full spectrum. “When we hawk watchers arrive on the first of September we look down on the city in full summer green. By the time we leave on October 31, most of the leaves are gone. We are blessed with seeing the complete transition of fall.”

And I’m thrilled to help this hawk transition back to its journey. “Now you’re going to be the Statue of Liberty,” Gail instructed. “Hold your arm up high. When Erik counts to three, give it a little toss into the air.”

I raised my right arm high—thrilled to hold such an amazing creature for even a few seconds—and thrilled to be a part of its freedom. “One...two...three!” counted Erik. I released my grip with a gentle toss, and watched in awe as the raptor took flight. It swooped down below the cliff, and darted around trees before disappearing from sight. Close on its tail, three more hawks materialized out of the north, and zipped past the eager crowd.

“It’s hawk migration season!” exclaimed Gail. “We love helping people experience this great event!” 

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