Acadia National Park's Hawk Watch program goes back 25 years/Friends of Acadia, Ashley Conti

Editor's note: The following article, by Seth Benz of the Schoodic Institute, appears in Friends of Acadia's Winter Journal.

Hawk watching in Acadia National Park formally came of age a quarter of a century ago.

Cadillac Mountain’s geographical position, located north of latitude N44 in the northeast corner of the United States, is considered the headwaters of a great southbound aerial river of migrating raptors. The birds come out of eastern Canada as well as Washington and Hancock counties here in Maine.

They will eventually join up with other geographical tributaries of hawks. Numbers swell into the tens of thousands as the airborne flow of raptors passes through both Pennsylvania’s Hawk Mountain Sanctuary and Cape May, New Jersey.

Four weeks after passing Cadillac Mountain, the hawks reach Corpus Christi, Texas, where tallies reach 100,000 or more. One week after that, numbers at Veracruz, Mexico can be in the millions!

Hawk Watch on Cadillac is a special, stationary form of bird watching — a point count designed to monitor the autumn’s seasonal passage of migratory birds of prey. The actual spot is a small exposed outcrop of granite located just a couple hundred yards west of the summit parking lot along Cadillac’s North Ridge Trail.

The effort is a collaborative operation between park interpreters, a Friends of Acadia-sponsored raptor intern, and Schoodic Institute’s Bird Ecology Program which recruits and trains volunteer citizen-scientists and then collates data. Daily counts take place from 9 a.m. to 2 p.m. from mid-August through mid-October. Anyone can drop in at any time.

In Spring, when the hawks migrate northward, they tend to disperse across the continent by using different flyways than those taken in the fall.

At Cadillac, for instance, we have detected no concentrated flyway. Hence, no Spring count is conducted.

Looking for raptors from Cadillac Mountain/Friends of Acadia, Ashley Conti

Observers use 8 or 10X binoculars to spot and identify hawks. Observations are recorded by the hour on a standardized data sheet and reports are sent to a national repository. Visitors are welcome and encouraged to participate by helping to spot migrants. They also can learn from the expertise and camaraderie of more experienced hawk watchers and the educational messaging imparted by the rangers.

Observers use the names of landscape features to point out where each hawk appears. “There’s a bird half a glass over Bald Porcupine moving toward Bar Island, going fast,” says one. “I can see pointed wings, looks like a falcon,” reports another. “Yes, I got it. It’s a Peregrine!” exalts a ranger.

Each hawk inspires passionate descriptors like that, called out to seize onlooker’s attention on the subject bird of the moment.

Each hawk is identified by looking at shape, size, flight style, and field marks. Making a positive identification sounds easy until someone actually tries it.

In addition to quickly locating the hawk, observers must factor in wind conditions, cloud cover (which impacts lighting), distance, and angle of proper focus to see plumage detail, if any. Lastly, the gestalt of the bird — how it carries itself, coupled with its flight behavior — must be considered. Even with careful scrutiny, not all can be identified. All, however, are counted. Some simply are listed as “unidentified raptor.”

Fourteen species have been spotted. Each is triggered to migrate separately as days shorten, temperatures cool, and winds blow from the north. Since Cadillac’s inaugural hawk watch day on August 28, 1995, through October 9, 2019, a grand total of 71,681 hawks have been tallied. A typical hour of observation produces 12 sightings.

Three species predominate: Sharp-shinned Hawk (36 percent), Broad-winged Hawk (23 percent), and American Kestrel (21 percent). The remaining 20 percent is spread among the other 11 species.

Over time, population trends emerge. Watchers have documented a resurgence of the American Bald Eagle, once depleted by DDT. Statistics support evidence of a northward range expansion by Turkey Vultures.

And, despite the statistical likelihood of spotting a Sharp-shinned Hawk or American Kestrel, data suggest both species are in decline — likely due to a depletion of the songbirds and insects they respectively feed upon. Additionally, researchers are investigating potential shifts in timing of migration by different species.

In a very direct way, the initial proposal to establish a hawk watch site in Acadia National Park drew inspiration from Hawk Mountain Sanctuary in Pennsylvania. It was the very first hawk watch site in the world, established in 1934. The Cadillac Mountain program is fashioned with a pedigree that exemplifies dedicated volunteerism, scientific inquiry, and conservation education.

We hope to continue to deliver the enjoyment, edification, and visitor engagement in the phenomenon of hawk migration long into the future.

On a morning this past October, a northwest wind and the sound and sight of familiar friends already arrived heightens the anticipation. Everyone wears layers of warm clothing, watch caps and gloves. Binoculars are up and scanning.

Several voices compete to share location instructions as the first bird is spotted. A play-by-play of the flight characteristics is shared, "short, rounded wings, longish tail, quick flap, flap, and glide.”

“Sharp-shinned Hawk,” someone yells out and we all agree.

While waiting for the next one, tips are traded on what clues told us it was a Sharpie. Often, folks imagine the bird's origin and possible winter destination which is something that will never be known.

Contemplation is short-lived. Another hawk is spotted, binocs swing up, and the cycle repeats.

Seth Benz of Belfast heads up the Schoodic Institute Bird Ecology Program, where he combines research, education, and citizen science to study bird migration and the sequencing of nature's events.