Season Overview
Derby Hill conducted its annual hawk count this past spring from March 1st to May 31st. This is the 41st consecutive season this full time count has been done, providing an invaluable source of data, which shows many interesting trends. In 2019, we counted a record 101,834 raptors, which is over 32,000 higher than any previous season. This increase is mostly due to a very healthy Broad-winged Hawk Count of 63,639, which is almost 26,000 higher than any previous season for this species. The record count of 27,981 Turkey Vultures for the season certainly helped bring this spring’s count over the magic 100,000 mark. Bald Eagles and Peregrine Falcons also had their best season ever at Derby this spring, two species which are clearly increasing in population. Although we will likely see numbers of Turkey Vultures, Bald Eagles, and Peregrine Falcons continue to increase, the Broad-winged Hawk count may be hard to beat in future years.
As with a few past years, such as the count done in 2013 by Steve Kolbe, I made a huge effort to count every single bird that was migrating passed Derby Hill this spring. The result was nearly one million birds (!), though we fell a little short of that goal, with “only” 979,925 total birds of 198 species. With all the early mornings spent waiting for birds to migrate, we also ended up with a record number of observations hours (753), which is perhaps a sort of dubious honor. The effort to count all migrating birds was made very easy by using the Dunkadoo app, which Derby Hill started using last year, and I encourage future counters to try the same thing. As I have said at all the hawk counts I have done, all the birds are important, not just the raptors, so if you’re standing there counting hawks anyway, why not just count everything else too?
Monthly Review
February
Bill Purcell came out and counted for 1.5 hours on February 24th and saw 5 Bald Eagles and a Rough-legged Hawk.
March
The official season began on March 1st as always, and 6,298 raptors were seen, which is about average. The first week was very slow, with cold temperatures, snow showers, and NW winds.. In fact, things didn’t really get going until March 14th when 192 raptors were seen, with good numbers of buteos coming over the North Lookout, and my first chance to see close Red-shoulders lit up from underneath by the snow on the ground, one of the reasons I chose to come to Derby Hill! March 14th was also the first big push of non-raptors, with over 35,000 Red-winged Blackbirds, nearly 10,000 Canada Geese, and 7242 American Crows.. There were also huge flights of non-raptors on the 20th-21st, dominated by tens of thousands of Snow Geese, but there were also many other waterfowl and blackbirds as well. In typical March fashion, the 22nd-26th returned to cold weather and N winds, so not as much was happening, but a shift to S winds on the 27th-29th brought many raptors and non-raptors, including the first days over 1,000 raptors, dominated by Turkey Vultures of course, but there was good diversity of other species as well. Suddenly there were birds everywhere, with all the waterfowl, Tree Swallows, Common Loons, Eastern Phoebes, Double-crested Cormorants, Great Blue Herons, Sandhill Cranes, and Eastern Meadowlarks all being seen.
April
The total of 62,141 raptors seen this month was a new record, mostly due to the large flight of Broad-wings, with a peak of 14,862 on the 21st, and a total of 37,129 for the month. The numbers of other raptor species were more average. The first week of the month was dominated by Turkey Vultures, culminating on the 8th when 4,143 vultures were seen. There was also huge non-raptor flights of over 50,000 on the 7th and over 70,000 on the 8th, with some highlights being 38 Great Blue Herons, 14 Sandhill Cranes, and 42, 641 Common Grackles on the 7th, and 53 Common Loons, 4270 American Robins, and 34,890 Common Grackles on the 8th. More diversity was added to the flights during mid-month, including the first warblers and shorebirds, the beginning of a chickadee migration, good numbers of Northern Flickers, and small numbers of finches all started moving. Raptor numbers remained modest until the 19th when a push of 5,195 Broad-wings came ahead of a cold front, but no one was prepared for the huge flight of 14,862 Broad-wings that came over on the 21st. Only a few people were present to see the second highest count in Derby’s history, and this highly concentrated flight happened within just a few hours, with a single hour of over 8,000 birds overwhelming the counter in multiple flight lines. Although I have seen much larger flights at other locations, the special part of this flight was that the overcast sky and light lake breeze kept the birds very low, often right overhead. Two more good Broad-wing days included 4889 on the 23rd that were fairly low right over the North Lookout, and 6,121 on the 25th that started out very high over the North Lookout in the morning, then drifted way south of the South Lookout in the afternoon- more typical behavior for these fickle birds- wherever the wind blows, they blow! The remainder of the moth was slow for raptor and non-raptors.
May
As with April, May also had a record number of raptors, with the month’s total of 33,389 raptors dominated by 26,510 Broad-winged Hawks. As is typical at this latitude, the first week of May was awash with newly arriving neotropical migrants, with 10 species of warblers already present on the 2nd, and flights of 2012 Yellow-rumped Warblers on the 7th and 2367 Yellow-rumps on the 8th, but unfortunately the remainder of the month was relatively poor for warblers. A very large, late flight of 12,276 adult Broad-wings surprised us on the 6th when the morning’s fog suddenly cleared. There were also 136 Bald Eagles that day, a new high count for one day at Derby Hill. Other than a flight of 2787 immature Broad-wings on the 20th, and continued good numbers of Bald Eagles, raptor migration slowed down during mid-May as expected, and the days were filled with migrating Blue Jays instead, including a peak of over 9,000 on the 19th. Some great non-raptor flights mid-month were exactly what I had been waiting for all season! It is such a treat to walk out the door of the cottage and see flights of Green Herons, swallows, Chimney Swifts, Eastern Kingbirds, Red-headed Woodpeckers, Cedar Waxwings, warblers, orioles, Scarlet Tanagers, Rose-breasted Grosbeaks, Indigo Buntings, Bobolinks, and goldfinches all flying right overhead.
Species Summaries
Black Vulture
Only two Black Vultures were seen, which is about average, though numbers have been very slowly increasing at Derby Hill.
Turkey Vulture
The total of 27,981 Turkey Vultures sets a new seasonal record, but this is a number that will likely be surpassed again in the near future as this species continues to increase in the region. The peak period was March 29th-April 13th, with 18,942 vultures (68% of the total). Although the peak day of 4,143 is one of the highest at Derby Hill, I’m convinced something more like 5-6,000 Turkey Vultures flew by that day, since the flight was lost to the south for several hours when rain and fog reduced the visibility, and I could only occasionally see large kettles many miles away. Luckily a switch in wind brought the flight line back to my position at the South Lookout later in the day.
Osprey
An above average total of 595 Ospreys were counted. Numbers of this species appear to be highly variable without an obvious trend. Sometime in late-April, I remember wondering why the Osprey count was so low this season- as it turns out, they just hadn’t arrived yet! The bulk of the flight didn’t happen until April 30th to May 9th, when 306 flew by (50% of the total), culminating in a nice peak of 70on May 9th. A local pair of Ospreys built a nest on the cell tower at the South Lookout.
Bald Eagle
The total of 1252 Bald Eagles also sets a new seasonal record, but as with Turkey Vulture, this is a number that will likely be surpassed again in the near future as this species continues to increase in numbers. One has to wonder, what is the saturation point for Bald Eagles? As a counter from Duluth, its pretty interesting to me that so few eagles pass over Derby in March (only 131 this year), even though that is the peak time for flights of northbound eagles in Duluth (where over 1,000 were counted in one day this spring!). In fact, the Bald Eagle migration didn’t really kick in at Derby until April 23rd when 47 were seen, and the vast majority of eagles were seen from April 23rd to May 26th when 929 were seen (74% of the total). We know that this late season push of Bald Eagles are birds of the southern race, dispersing north after their breeding season, so the question is: why isn’t there an early push of birds breeding in Northeastern Canada in March? They must not winter south of Derby Hill.
Northern Harrier
The total of 568 Northern Harriers was average, and the migration was spread out mostly from late March to early May, including a peak of 50 harriers on April 19th.
Sharp-shinned Hawk
The total of 3654 Sharpies was slightly below the long-term average, but slightly above the ten-year average. The bulk of migration was from April 12th to May 9th, with a peak of 478 on May 5th.
Cooper’s Hawk
The total of 215 Cooper’s is a bit below the ten-year average, and well below the overall long-term average. This species is clearly in decline, with five of the last ten years showing record low counts at Derby Hill. The bulk of migration was from March 15th to April 18th. The high count for one day was only 13, reached three times: March 15th, April 2nd, and April 18th. There was a resident pair of Cooper’s often seen west of the South Lookout.
Northern Goshawk
Only 15 Northern Goshawks were counted, which is lower than average, but this doesn’t really surprise me since the historical “invasions” that used to bring so many of these birds south no longer occur.
Red-shouldered Hawk
The season count of 427 was near the 10-year average, but well below the long-term average, with numbers of this species clearly on the decline. The first Red-shoulder did not appear until March 13th, and the bulk of migration was from March 14th to April 13th with a peak of 69 on April 2nd.
Broad-winged Hawk
The total of 63,639 Broad-wings sets a new seasonal record by a wide margin. To find the pervious best season, one has to travel all the way back to 1983 when a season of 37,647 was counted. The first Broad-wings showed up on April 12th, and within the same week, the first big push came on April 19th when 5,195 were seen. The peak of 14,862 Broad-wings on April 21st was the second highest day in Derby’s long history, and only about 600 birds short of the record set back in 1984. Additional good Broad-wing days of 4889 on April 23rd and 6121 on April 25th help round out the month’s numbers, but these guys were not done, since another big day of 12,276 came on May 6th, which seemed to be a near repeat of the big flight on April 21st. So why were there so many Broad-wings this season? I think there are always that many Broad-wings passing through the region, as evidenced by the usually higher counts at Braddock Bay, but the right combination of wind off the lake helped keep the birds within our range, as opposed to strong south winds which apparently blow the birds out over the lake where they are not visible from Derby Hill. This latter scenario appears to be more typical, which gives Braddock Bay its large flights, and leaves Derby Hill out of the loop- this season the reverse happened, and we ended up with the lion’s share of the birds.
Red-tailed Hawk
The season count of 2759 is well below average. A very disturbing trend in the data shows that numbers have really bottomed out recently, with the three lowest seasons on record all in the last four years. This is very disappointing for a Red-tail lover like me, but thankfully the season was amazing in so many other respects! The peak of adults was 382 on April 12th, while numbers in May were mostly immatures. No dark or rufous morph birds were seen.
Rough-legged Hawk
The total of 111 Rough-legs is below average. Interestingly, exactly as with Red-tails, three of the last four years have had record low seasons., but since this species is so cyclical in its numbers, there could easily be a rebound at Derby in the next few years. Nearly half of this season’s migration came by in just two days: 30 on March 14th and 17 on March 15th.
Golden Eagle
The total of 68 Goldens is above average, but this is no big surprise since this species is also increasing in numbers throughout the East. The two best days were 12 on March 27th and 10 on April 23rd.
American Kestrel
The total of 421 kestrels is above average, which is a good sign considering how much attention has been given to this species’ decline in population. Although no real peak period was noted, the peak day was 53 on April 18th.
Merlin
The total of 94 is the second best season to date. The peak days came surprisingly late, with 12 on May 1st and 11 on May 9th.
Peregrine Falcon
The count of 32 Peregrines is the best season ever, not that Derby Hill gets very many Peregrines! The count of five on May 9th is apparently a tie for the best day ever at Derby Hill.
Non-raptor Highlights
Snow Goose: total of 308,963 for the season, the most common bird at Derby Hill, representing 32% of the total birds seen. Some of the big days were 67,120 on March 20th, 75,243 on March 21st, and 64,615 on March 22nd. Apparently they waited long enough to move north this year, since there was not a big return flight as happens some years when they go too early.
Ross’s Goose: four seen between March 24th and April 7th.
Brant: total of 1191 for the season, including a single flock of 900 on May 26th.
Cackling Goose: total of 20 for the season, including a peak of 12 on March 20th.
Canada Goose: total of 56,954 for the season, with a peak of 11,010 on March 27th.
Wood Duck: total of 550 for the season, with a peak of 122 on March 15th.
Mourning Dove: total of 259 for the season, including a peak of 24 on March 30th. I was surprised that small numbers continued migrating into May.
Sandhill Crane: total of 58 for the season, including a peak of 14 on April 7th, which is apparently a record one-day count for Derby.
Killdeer: total of 263 for the season, including a peak of 119 on March 30th.
Common Loon: total of 295 for the season, including a peak of 53 on April 8th. There have been larger flights during previous seasons.
American White Pelican: a single bird on April 21st was unusual.
Great Blue Heron: total of 229 for the season, with a peak of 28 on March 30th. I expected more.
Green Heron: total of 35 for the season, with a peak of 10 on May 19th.
Northern Flicker: total of 715 for the season, including a peak of 179 on April 13th. Many fewer than expected, since days of over 1,000 flickers are not unusual in spring in the Great Lakes.
Great Crested Flycatcher: 10 were seen on May 19th, most of which were engaged in morning flight.
Eastern Kingbird: total of 171 for the season, including a peak of 52 on May 10th. Fewer than expected, since counts have been as high as 293 in one day in the past.
Blue Jay: total of 59,336 for the season including peaks of 7223 on May 5th and 9,014 on May 19th, which were all much higher than expected, though not record counts.
American Crow: total of 19,391 for the season including a peak of 7242 on March 14th, which is higher than recent years.
Tree Swallow: total of 2147 for the season, including 716 on May 1st.
Barn Swallow: total of 625 for the season, including peaks of 291 on May 1st and 215 on May 9th.
Black-capped Chickadee: total of 367 for the season including a peak of 94 on April 11th. I was expecting a huge chickadee migration here this spring since there was a big flight last fall in many areas, but after a promising start in mid-April this spring, the chickadee flight completely fizzled. Its worth noting that on the majority of days in April and May I was forced to move to the South Lookout by mid-to late morning due to a lake breeze, so its possible some chickadee migration was missed, since they migrate almost exclusively directly along the lakeshore, and often keep moving into mid-day. I did see one flock attempt to cross the big field at the South Lookout, but there’s no way a chickadee could accomplish such a feat and the birds turned around.
White-breasted Nuthatch: a flight of 36 was documented on April 9th, which was a surprise, since not many White-breasted Nuthatches are known to migrate, but small numbers do occasionally move.
Eastern Bluebird: total of 124 for the season, including 37 on May 9th. Its interesting that most of the migrant flocks of bluebirds seen are later in the season rather than in March when the local nesting birds arrive- where are these northbound May bluebirds headed?
American Robin: total of 14,579 for the season including peak days of 3307 on March 30th and 4270 on April 8th, but these numbers were much less than I had hoped. Not a big robin year at Derby.
European Starling: total of 11,000 for the season including a peak of 3250 on March 30th.
Cedar Waxwing: total of 3035 for the season including a peak of 960 on May 23rd. This species often continues migrating into June.
Evening Grosbeak: total of 18 including 8 on May 8th.. I had hoped there would be a better flight since it was a bit of an “invasion” year in the Northeast, but numbers are still just a fraction of what they used to be historically.
Purple Finch: total of 407 for the season, including 111 on April 26th. Not a good year for this species.
Pine Siskin: total of 367 for the season, including 197 on May 8th. Not a good year for this species.
Common Redpoll: total of 286 for the season, including 105 on April 8th. This was not a redpoll invasion year.
American Goldfinch: total of 5572 for the season including peaks of 1839 on May 8th and 2063 on May 9th, which are good counts, and follow an excellent fall flight in the East.
Bobolink: total of 212 for the season including 32 on May 9th. Fewer than expected since as many as 1200 have been seen in one day in the past.
Baltimore Oriole: total of 395 for the season including 110 on May 17th and 103 on May 19th, but this was a disappointing total since counts of 100s of orioles in a day are not unusually in spring on the lower Great Lakes.
Red-winged Blackbird: total of 171,712 for the season including a peak of 35,409 on March 14th. Though impressive, these numbers are still just a fraction of what happened here historically when counts of almost a million have occurred.
Brown-headed Cowbird: total of 3325 for the season, with a peak of 1414 on April 2nd, but as with other blackbirds, these numbers are much lower than historical counts.
Rusty Blackbird: total of 3024 for the season including 997 on May 3rd and 1010 on April 26th, which are probably some of the best counts ever for Derby, but few observers probably try to pick out the Rusties from the large blackbird flocks that occur throughout the season. Both big days were in the rain.
Common Grackle: total of 182,495 for the season, including peaks of 42,641 on April 7th and 34,890 on April 8th, which was later than I realized the peak would be. Numbers are a fraction of historical counts.
Yellow-rumped Warbler: total of 7475 for the season including high counts of 2012 on May7th and 2367 on May 8th, which are good counts for Derby.
Scarlet Tanager: total of 93 for the season, including 32 on May 17th and 26 on May 19th, both of which appear to be high counts for Derby. More than expected.
Rose-breasted Grosbeak: total of 32 for the season, fewer than expected since as many as 58 have been seen in a single day in the past.
Indigo Bunting: a total of 19 for the season, most of which were on May 19th when 13 were seen. Fewer than expected.
Acknowledgements
I greatly enjoyed my first season at Derby Hill, a place I have always wanted to visit in spring. I had heard so much about the great set-up to witness visible migration, and I was not disappointed. I never expected to see almost one million birds! I would like to thank Dave Fitch for making it all possible and for keep the cottage in such great shape. Having such a comfortable place to live directly on site is fairly unique and its one of the things that make Derby Hill such a fun and relaxing place to work. I would also like to thank all the friendly folks who showed up to watch migration, help spot birds, and even bring treats: Joe Brin, Ron Burdick, Peter Davidson, Dave Fitch, Deborah Dohne, Chris and Sally Holt, Kevin McGann, Charlie Long, Dong Metzger, Bill Purcell, Chris Reynolds, Andy Saunders, Mickey Scilingo, Paul Shanahan, Phil Taylor, Judy Thurber, and Dave Wheeler were all regulars, though of course there were lots of other folks who came to visit as well. Finally, I would like to give a special thanks to Bill Purcell for giving me some time off, especially during the last five days of the count.
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