Wednesday, September 21, 2011

Broad-winged Hawk Migration

One of the most amazing spectacles of the avian world is the Fall migration of Broad-winged Hawks along the east coast of North America. During this period hundreds of thousands of these normally solitary raptors converge for their flight to southern wintering grounds. There are several locations within a short drive of NYC where, if the timing is right, this annual swarming of hawks can be experienced. Hook Mountain is one of those spots and over the past weekend conditions were perfect for witnessing a massive push of Broad-wings.

Located approximately 31 miles north of the city, Hook Mt. is situated on the west shore of the Hudson River. Below it, to the north, is Rockland Lake State Park. To the south, a view of the Tappen Zee Bridge and Piermont Pier. The tallest skyscapers of midtown Manhattan can be seen peeking over the top of a low ridge to the south-southwest.

For the last month it seemed as if the eastern edge of the country had been seeing a virtual endless stream of storm systems moving up the coast from the south. Like most species of migrating birds, Broad-winged Hawks wait for a cold front accompanied by north winds before heading south. By Friday the weather finally turned, so I had a good feeling about seeing a big push of raptors over the weekend. Robin, Heydi and I made plans to head up to Hook Mt. early Saturday morning.

We arrived at the pull-off for the trailhead on route 9W by about 8:30am. There were already seven cars parked. I guess a lot of other birders had the same idea. The trail to the top of the ridge is relatively easy, with the last 15-20 yards being a fairly steep rocky scramble. By the time we arrived at the hawkwatch, there were already about 20 people present. After a week of lackluster numbers (15 were seen on Monday), Friday's count total was 1072 Broad-winged Hawks. Everyone was optimistic that it would be a good day.

I found out that the hour before we arrived had already seen 500 broad-wings. We had only been on the mountain for about 15 minutes when someone shouted that a kettle was coming in from the north. There appeared to be 20-30 hawks in the flock. As the flock got closer to Hook Mt., it began to veer to the west. Within a short time another flock appeared heading our way. And then another. And another. Some of the hawks were coming up from below the south side of the ridge and passing by at eye level. Trudy was the head counter and by late morning I joked that smoke was starting to come off of the chrome, mechanical counter that never left her hand. In between flocks of broad-wingeds, individual Sharp-shinned Hawks zipped overhead. A pair of Bald Eagles soared over a stone quarry just passed Rockland Lake. A resident Red-tailed Hawk took exception to the plastic Great Horned Owl mounted on a tall pole and screeched a raspy "keeerr" while circling the permanently frozen owl. Two or more ravens flew back and forth across the ridge all morning.

Here's one small kettle of hawk

Tom pointed out the largest flock of hawks of the day just before 11am. The birds were streaming across the northern horizon in an unbroken line from the east to the west. The experienced counters present estimated that there were about 1,000 individuals in that grouping. As the air warmed and the flocks moved closer to our perch on Hook Mt., I put down my binoculars and studied the hawk's technique for conserving energy. Individuals would enter a rising column of air. Barely moving their wings, they'd soar to the top of the warm air as if riding an elevator. Dozens and, sometimes, hundreds of hawks would feed into this free ride like a hopper. As they approached the top of the thermal where the air cooled, they would break off and stream across the sky to the next column of air. Reaching the thermal at a lower altitude, they would rise up, circling within the warm column until they reached the top, where they would again peel off and soar to the next column. I pictured in my mind hundreds of thousands of Broad-winged Hawks leap-frogging between thermals as they made they way south, across Central American and into South America.

When clouds started to roll in at around 1pm we decided to call it a day and head back to Brooklyn. At that point the official Broad-winged Hawk total was 13,660. I read on the Hook Mountain website the next day that the final count for the day was an astounding 14,670! It's really nice when the weather and birds cooperative with us on the weekend.

Here is a video from Trudy Battaly's Hook Mountain Hawkwatch Website:


Here are the official totals for Saturday's hawkwatch:

2 comments:

Yojimbot said...

awesome!

outwalkingthedog said...

Wow wow wow that is amazing. Glad you had a great hawk day so I can get that vicarious thrill!

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