EYES TO THE SKIES
Broad-winged hawks and bald eagles the big winners at Hawk Mountain during the fall migration
“Every year, you know, there are winners and losers,” David Barber said as he settled into a comfortable chair at the Acopian Center for Conservation Learning at Hawk Mountain Sanctuary.
That was a change from most of the fall, when the senior research biologist at the sanctuary had perched on a rock atop the North Lookout, monitoring the fall hawk flights during a season that began Aug. 15 and ended Dec. 15.
When assessing the flight season, though, Barber cautioned, it’s always more important to look at the flights in context of the 10year average to establish population trends.
“Our overall count was about 25% higher than average, which was great,” Barber said. “But that was really due to two species. We had above-average counts for bald eagles, about 20% above average, and then the broad-winged hawks were our most abundant migrant as usual, but they were 60% above average.”
So the big winners this past fall were the broad-winged hawks, he said.
During four remarkable days in mid-September, from the 16th through the 19th, over 10,000 broadwings flowed over the lookout.
“It was incredible,” Barber said. “Probably the most memorable moment was on that Sunday when in one hour we had a continuous stream going through, over 1,900 birds.”
No one present on the lookout had ever witnessed a flight like that before.
“What was really cool was that there were probably four counters up there,” he continued, “and we all turned and looked at each other; we’ve never seen anything like that. We had probably over 70 years worth of counting years among us.”
The season total for the broadwinged hawk was 12,503 birds, the ninth-highest number recorded since counts began in 1934. The 10-year average is 7,793.
The bald eagles were another winner.
“Bald eagles are moving into appropriate habitats, and their nest success is very high,” Barber said. “They’re just a tremendous success story.”
This fall, 591 bald eagles passed the lookout, a 21% increase over the 486 10-year average. The daily high count was 38 on Sept. 23, with 22 going over after 4 p.m.
Unfortunately, none of the other 14 raptor species seen at Hawk Mountain surpassed their 10-year averages.
The bird that is causing the most concern is the northern goshawk.
Four goshawks were recorded this past fall. That was an improvement over the single bird seen last year, but the 10-year average has been 14, representing a 71% drop.
“Last year, one was the high count for any watch sight in Pennsylvania, and this year, Wagner’s Gap (near Carlisle) had 16,” Barber said. “So we’re recording some, which is encouraging. But, you know, there was only one confirmed nest in Pennsylvania last year. They’re really kind of in a freefall.”
The vagaries of wind and weather also influenced the numbers of birds seen over the lookout by the five staff and 15 volunteer counters over the course of the season.
Golden eagle numbers were also down this year, probably due to the weather.
“The golden eagle count was a little low,” Barber said. “We had a total of 107, which was 17% below average. It had seemed like the flight was late this year for golden eagles. And we just didn’t have really strong northwest winds. Bracken (Brown, another staff counter) was up later in December on good winds and he had several goldens going through. But Allegheny Front, I think, had a record golden eagle year this year. So it’s possible that a lot of the birds drifted to the west of us.”
Red-tailed hawk numbers were also down.
That seems surprising considering that the redtail is the ubiquitous hawk of the Berks County roadsides and farm fields.
“Redtail numbers are decreasing, our counts are decreasing,” Barber said, “but we think that the those birds are actually short stopping.”
Short stopping?
“Short stopping is not migrating as far as they used to,” he said. “For a migratory species, migration is the most energetically expensive part of the year. And so if a bird doesn’t need to migrate, if there’s food available, then it’s a better option not to migrate.”
There were also other avian winners besides broadwings and bald eagles at the lookout this past fall.
“Besides raptors, we had a really good northern finch year,” Barber said. “We had both species of crossbills, the red- and the white-winged, and evening grosbeaks. We had common redpolls on one of the last days.”
Also a first for the fall migration count were dickcissels, a grassland bird.
“We also had three Bonaparte’s gulls, which was nice,” he said. “That’s an unusual migrant.”
Another highlight was three sandhill cranes.
“I’ve seen them before, but not in Pennsylvania,” Barber said. “And not from North Lookout.”
For the fall, 20,347 raptors were counted migrating over the North Lookout, a 25% increase over the 10-year average of 16,317.
“Looking at one year’s worth of data doesn’t tell you a whole lot,” Barber said. “It’s really looking at the long-term numbers, looking at long-term trends, that we can start to see what species might be affected by different factors. So again, one year’s worth of data doesn’t really tell you a whole lot.
“It’s the overall long-term numbers that can really tell your story.”
To view the day-to-day count totals, visit Hawk Mountain’s website at www.hawkmountain. org.