2024 was the 24th full season of the spring hawk watch at Tussey Mt,
staffed daily Feb 20-Apr 26. The watch site is located on the top of Tussey
Mt, the second ridge from the north and west in the western
Ridge-and-Valley physiographic province and near the boundary between
Huntingdon and Centre counties. The watch’s primary focus is monitoring the
spring Golden Eagle migration. This report reflects that focus.
Annual Golden Eagle totals at western sites such as Bridger Mts, MT; Mt
Lorette, AB; and Gunsight Mt, AK, are commonly around 1,000-2,000. However,
they draw from a western population of approximately 60,000 birds. The
eastern Golden Eagle population is thought to have about 4,000-5,000 birds.
Among eastern watch sites, the Golden Eagle total at Tussey Mt ranks second
to Mackinac Straits, MI, in the spring, while Bald Eagle Mt ranks first in
the fall (Table 1). No other spring site east of Michigan consistently
counts close to the number of Golden Eagles that we do at Tussey Mt,
although the 2024 total at the Allegheny Front site was close. Thus, these
local hawk watches are important in monitoring the eastern population.
*Table 1. 10-Year Golden Eagle Averages (2014-2023) at Some Eastern North
American Watch Sites.*
*Spring*
*Fall*
*Site*
*10-year average*
*Site*
*10-year average*
Tussey Mt, PA
169
Bald Eagle Mt, PA #
324
Allegheny Front, PA
80
Allegheny Front, PA
208
Derby Hill, NY
55
Franklin Mt, NY
178
Braddock Bay, NY
27
Stone Mt, PA
150
Mackinac Straits, MI
231
Jacks Mt, PA
128
West Skyline, MN *
155
Waggoner’s Gap, PA
215
Hawk Mt, PA
123
Detroit River, MI
82
Holiday Beach, ON
59
Hawk Ridge, MN
195
* - 6-year average for West Skyline; # - 4-year average for Bald Eagle Mt
The 2024 official counter was Andrew Bechdel, who returned for a second
year. Andrew did an excellent job; he was very diligent and his increased
raptor ID skills were apparent. He joints a cohort of distinguished local
birders who have been hawk watch counters at Tussey Mt: Jon Kauffman in
2009-2010 and 2014, Lewis Grove in 2017, and Sean McLaughlin in 2021 (Sean
has subsequently counted raptors in Duluth, MN, at the West Skyline site in
the spring and the Hawk Ridge site in the fall).
The 2024 watch was conducted on 56 days, with 414 hours of watching. This
closely matches past median (middle) effort of 56 days and 403 hours. We
accomplished our primary goal of conducting the watch over the same time
span as previous years and with similar hours and watchfulness. Season
totals are shown in Table 2.
*Table 2. 2024 season totals and 10-year averages (2014-2023). *
*Species*
*2024*
*10-year average*
*2024 Ranking*
Turkey Vulture
196
186
average
Osprey
59
89
below average
Bald Eagle
69
69
average
Northern Harrier
19
21
average
Sharp-shinned Hawk
203
162
above average
Cooper’s Hawk
28
26
average
American Goshawk
0
1
Red-shouldered Hawk
35
40
average
Broad-winged Hawk
1378
920
above average
Red-tailed Hawk
213
286
below average
Rough-legged Hawk
0
2
Golden Eagle
164
169
average
American Kestrel
38
42
average
Merlin
4
6
average
Peregrine Falcon
4
3
average
Total
2425
2020
Below-average counts were observed for Osprey and Red-tailed Hawk, but
these observations were consistent with long-term trends. Ospreys in
Northeastern North America have been experiencing a decline, possibly
related to the rise of Bald Eagles, and there is evidence that Red-tailed
Hawks are not migrating as much as their ancestors did. Above-average
counts were observed for Sharp-shinned Hawk and Broad-winged Hawk. The
Sharp-shinned Hawk count was the highest since 2104 and was somewhat
surprising since we had observed low Sharp-shinned Hawk totals during the
previous fall. The 1378 Broad-winged Hawks was our 4th highest season
total; 83% were observed during a four-day period, Apr 15-18. All other
raptor species were observed in average numbers.
The 24-year trend in Golden Eagle total count has an overall hill shape,
with lower counts during 2001-2007 (average 161), higher counts during
2008-2015 (average 205), and lower counts again in 2016-2024 (average 153).
The 2024 total of 164 was just below the 10-year average of 169 and welcome
after 2023’s low count of 118 (Figure 1). I suspect that lower totals occur
when less severe winters cause Golden Eagles to winter farther north than
they previously did or allow them to begin filtering back north before the
spring migration begins in earnest during late February and early March.
Sometimes, as in 2023, a sustained W/NW wind regime in the first half of
March seems to limit Golden Eagle counts, but the 2024 wind regime was much
more favorable during the peak Golden Eagle migration period.
The first detections of migrating Golden Eagles at Tussey Mt have been
fairly consistent across seasons, so there is no indication that many have
moved past us before we start (the Allegheny Front watch starts earlier
than we do and they have only detected a few before we start). In 2024, we
recorded the first three Golden Eagles on Feb 21 and the first significant
count, nine, on Feb 26. They then came with a rush in early March, with 95
counted during the first 12 days (which includes four rain days), 58% of
the season’s total. The high count was 27 on Mar 8. The cumulative Golden
Eagle chart shows that the 2024 count was slightly ahead of the long-term
average through Mar 16, but from mid-March on, the detection pattern was
very similar to the observations of other years (Figure 2).
The best winds at Tussey Mt are from the S or SE, which we observed on Feb
26-27 and Mar 1, 3,4, 8, and 11-12. This largely explains the early Golden
Eagle movement. At the Allegheny Front hawk watch, on the Allegheny Front
west of Bedford and about 61 air miles to our southwest, favorable flights
occur when winds are from the E or SE. The Allegheny Front site experienced
their best Golden Eagle count this season and it was concentrated during
the same time period as the good flights at Tussey Mt (Figure 3).
Interestingly, the Derby Hill, NY, site, near the SE end of Lake Ontario,
also has experienced one of their best Golden Eagle seasons (Figure 4).
I suspect that when a sustained period of S or SE winds occurs during the
peak period, as happened this year, a large percentage of Golden Eagles
moves north along the Allegheny Front and Laurel Ridge to its west and we
miss seeing those birds. I have noticed before that sustained S or SE winds
seem to push many Golden Eagles toward the Allegheny Front and, at Tussey
Mt, I theorize that we need periods of both S/SE and W/NW to keep them on
our ridge. While Tussey Mt has many of its best flights on S/SE winds, we
also see Golden Eagles on W/NW winds. Tussey Mt is not situated along a
landscape feature that is commonly called a “leading line”, like at the
Great Lakes sites, or acts as a natural “collector” of Golden Eagles, like
Bald Eagle Mt does in the fall. Instead, we benefit from the length of our
ridge, which extends south into Maryland, and its location in the western
Ridge & Valley.
The shapes of the three cumulative curves help to tell a story about the
three sites. Counts at Tussey Mt have been more consistent, which I believe
is related to the many Golden Eagles moving through here and the
consistency of our effort over the years. Counts at Allegheny Front have
been more variable largely because of that site’s strong dependency on E
and SE winds. Derby Hill observations are dominated by immature birds, as
shown by consistent flights occurring in April. However, as in 2024 and
2021, they sometimes see many Golden Eagles in March, probably related to
more adult Golden Eagles being seen there when winds have been from the S
or SE.
Thanks to our sponsors, Shaver’s Creek Environmental Center, the State
College Bird Club, and individuals. Also, thanks to the many people who
visited and helped to spot migrating raptors; we appreciate all the good
help. Next year will be our 25th season, a good milestone to achieve.
