Date: 4/28/24 10:05 am From: David Brandes <000016035b42742c-dmarc-request...> Subject: Re: 2024 Tussey Mt hawk watch summary
Fantastic report, Nick! so grateful to you and Jon for keeping this important site running all these years, and to Andrew for continuing the tradition of counting excellence!
Dave Brandes
On Saturday, April 27, 2024 at 04:43:04 PM EDT, Nick Bolgiano <nickbolgiano...> wrote:
2024 was the 24th full season of the spring hawkwatch at Tussey Mt, staffed daily Feb 20-Apr 26. The watch site is located onthe top of Tussey Mt, the second ridge from the north and west in the westernRidge-and-Valley physiographic province and near the boundary betweenHuntingdon and Centre counties. The watch’s primary focus is monitoring thespring Golden Eagle migration. This report reflects that focus.
Annual Golden Eagle totals at western sites such as BridgerMts, 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 easternGolden Eagle population is thought to have about 4,000-5,000 birds. Amongeastern watch sites, the Golden Eagle total at Tussey Mt ranks second toMackinac Straits, MI, in the spring, while Bald Eagle Mt ranks first in thefall (Table 1). No other spring site east of Michigan consistently counts closeto the number of Golden Eagles that we do at Tussey Mt, although the 2024 totalat the Allegheny Front site was close. Thus, these local hawk watches areimportant in monitoring the eastern population.
Table 1. 10-Year Golden Eagle Averages (2014-2023) at SomeEastern 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 forBald Eagle Mt
The 2024 official counter was Andrew Bechdel, who returnedfor a second year. Andrew did an excellent job; he was very diligent and hisincreased raptor ID skills were apparent. He joints a cohort of distinguished localbirders who have been hawk watch counters at Tussey Mt: Jon Kauffman in2009-2010 and 2014, Lewis Grove in 2017, and Sean McLaughlin in 2021 (Sean has subsequentlycounted raptors in Duluth, MN, at the West Skyline site in the spring and the HawkRidge site in the fall).
The 2024 watch was conducted on 56 days, with 414 hours ofwatching. This closely matches past median (middle) effort of 56 days and 403hours. We accomplished our primary goal of conducting the watch over the sametime span as previous years and with similar hours and watchfulness. Seasontotals 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
|
|
|
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-tailedHawk, but these observations were consistent with long-term trends. Ospreys in NortheasternNorth America have been experiencing a decline, possibly related to the rise ofBald Eagles, and there is evidence that Red-tailed Hawks are not migrating as muchas their ancestors did. Above-average counts were observed for Sharp-shinnedHawk and Broad-winged Hawk. The Sharp-shinned Hawk count was the highest since2104 and was somewhat surprising since we had observed low Sharp-shinned Hawktotals during the previous fall. The 1378 Broad-winged Hawks was our 4thhighest 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 overallhill shape, with lower counts during 2001-2007 (average 161), higher counts during2008-2015 (average 205), and lower counts again in 2016-2024 (average 153). The2024 total of 164 was just below the 10-year average of 169 and welcome after2023’s low count of 118 (Figure 1). I suspect that lower totals occur when lesssevere winters cause Golden Eagles to winter farther north than they previouslydid or allow them to begin filtering back north before the spring migrationbegins 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 GoldenEagle counts, but the 2024 wind regime was much more favorable during the peakGolden Eagle migration period.
The first detections of migrating Golden Eagles at Tussey Mthave been fairly consistent across seasons, so there is no indication that manyhave moved past us before we start (the Allegheny Front watch starts earlier thanwe do and they have only detected a few before we start). In 2024, we recordedthe 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 duringthe first 12 days (which includes four rain days), 58% of the season’s total. Thehigh count was 27 on Mar 8. The cumulative Golden Eagle chart shows that the2024 count was slightly ahead of the long-term average through Mar 16, but frommid-March on, the detection pattern was very similar to the observations ofother years (Figure 2).
The best winds at Tussey Mt are from the S or SE, which weobserved on Feb 26-27 and Mar 1, 3,4, 8, and 11-12. This largely explains theearly Golden Eagle movement. At the Allegheny Front hawk watch, on the AlleghenyFront west of Bedford and about 61 air miles to our southwest, favorableflights occur when winds are from the E or SE. The Allegheny Front siteexperienced their best Golden Eagle count this season and it was concentratedduring 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 experiencedone of their best Golden Eagle seasons (Figure 4).
I suspect that when a sustained period of S or SE windsoccurs during the peak period, as happened this year, a large percentage ofGolden Eagles moves north along the Allegheny Front and Laurel Ridge to itswest and we miss seeing those birds. I have noticed before that sustained S orSE winds seem to push many Golden Eagles toward the Allegheny Front and, atTussey Mt, I theorize that we need periods of both S/SE and W/NW to keep them onour ridge. While Tussey Mt has many of its best flights on S/SE winds, we alsosee Golden Eagles on W/NW winds. Tussey Mt is not situated along a landscapefeature that is commonly called a “leading line”, like at the Great Lakessites, or acts as a natural “collector” of Golden Eagles, like Bald Eagle Mt doesin the fall. Instead, we benefit from the length of our ridge, which extendssouth into Maryland, and its location in the western Ridge & Valley.
The shapes of the three cumulative curves help to tell a storyabout the three sites. Counts at Tussey Mt have been more consistent, which Ibelieve is related to the many Golden Eagles moving through here and theconsistency of our effort over the years. Counts at Allegheny Front have been morevariable largely because of that site’s strong dependency on E and SE winds. DerbyHill observations are dominated by immature birds, as shown by consistent flightsoccurring in April. However, as in 2024 and 2021, they sometimes see manyGolden Eagles in March, probably related to more adult Golden Eagles being seenthere 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 visitedand helped to spot migrating raptors; we appreciate all the good help. Nextyear will be our 25th season, a good milestone to achieve.
