Impromptu Hawk Watch - 14 Aug 2019
This morning I received an e-mail from Mark Wloch and Dave Dister regarding a mid-August flight of Red-tailed Hawks near Ludington, MI:
Today while Matt McConnell was working on home repairs for a client in Ludington he noticed a steady movement of hawks flying south/southeast high above his work site on Robert Street (beginning around 10:00 a.m.). He had no binoculars, but could see "pale windows" in the primaries and believed the birds were mostly Red-shouldered Hawks. By the time he emailed me at 2:50 p.m. he stated that "they have been coming in waves in 4-6 a group" and totaled at least 200 birds !! I met him at the work site by 3:30 p.m. and started taking photos of hawks flying at a distance. All of the birds I photographed were Red-tailed Hawks, some of which showed "large rectangular windows" in the primaries when backlit (see photo 1). Once Matt concluded his work around 3:50 p.m. I left and headed northeast to the tennis courts on Tinkham Avenue ( 1.2 miles east of Lake Michigan) that had good sky visibility. After 10 minutes I then saw a kettle of 9 more RTHAs, but the movement tailed-off rapidly by 4:30 p.m.
It was my understanding that RTHAs were much more frequent in fall migration in September than RSHAs (of course, RTHAs breed north to James Bay, Ont., whereas RSHAs breed no further north than the UP of Mich.). Once at home I verified this by checking the September 2018 Detroit River Hawk Watch which tallied 138 RTHAs vs. 1 RSHAs (as well as other sites). Neither Matt nor I are raptor migration experts, but nonetheless, this very early movement of RTHAs on Northeast to North to Northwest winds appears to be unprecedented for this region of the state. Information to the contrary is of course welcome.
My immediate response was "cool!", then went on with life thinking not much of it. Robin and I are up here in Leelenau, MI for a quick getaway, so while she takes an art class in Glen Arbor, I drove up to Leelenau State Park at the northernmost tip of the peninsula. I hiked the trails around Mud Lake and was heading toward the Lake Michigan shoreline with the hopes of finding a late-season Piping Plover when I looked through a break in the forest canopy and spotted a small kettle of raptors.
Looking up I found a pair of Red-tailed Hawks and 3 Broad-winged Hawks soaring at different elevations. As I watched them circles I spotted another four Red-tails streaming to the NW toward the Lake Michigan shoreline. I beat it back to the car to grab my digiscoping gear, and set up the scope in the parking lot of the state park. It was about 10:30 am.
For the next hour I watched as dozens of Red-tailed Hawks streamed NW toward Lake Michigan from farther south inland. Skies were clear with just a few wispy cumulus clouds, but they were needed in order to see the birds that were moving at extremely high elevations.
Once things slowed, I hopped into the car to head to the Leelenau Lighthouse to see if I could see any more birds moving along the lakeshore. Water levels were high enough at the point that the lakeside trail behind the lighthouse was under water. I did not see any hawks overhead, but on the way back to the car I managed to spot a Nashville Warbler foraging among a flock of Cedar Waxwings.
Once things slowed, I hopped into the car to head to the Leelenau Lighthouse to see if I could see any more birds moving along the lakeshore. Water levels were high enough at the point that the lakeside trail behind the lighthouse was under water. I did not see any hawks overhead, but on the way back to the car I managed to spot a Nashville Warbler foraging among a flock of Cedar Waxwings.
Once at the car I spotted two Red-tailed Hawks soaring low over the trees, so I took off after them. No sooner than I left the park I spotted a small kettle of hawks soaring overhead, again at different elevations. Driving south on M-22 just north of the town of Leelenau I had to pull over when I spotted a kettle of about 40 birds soaring over an open field. I spent some time photographing the birds that were backlit by the Sun. They too had large rectangular windows in their primaries. That is, they matched Dave Dister's description of his birds from yesterday. So, I pulled over and posted to Birders@GreatLakes.Net, which prompted some interesting inputs from Paul Cypher and Josh Haas.
Paul had mentioned that many years back in Braddock Bay, NY there was discussion among hawk watchers that mid-August movements of birds like Red-tailed Hawks were due to post-breeding dispersal. Typically, this involves juvenile birds that leave their natal sites for new temporary sites prior to actual migration, or to look for potential breeding sites. While I couldn't find any articles specific to post-breeding dispersal, I did find an article (1) that shows a model of potential dispersal among raptors
Paul had mentioned that many years back in Braddock Bay, NY there was discussion among hawk watchers that mid-August movements of birds like Red-tailed Hawks were due to post-breeding dispersal. Typically, this involves juvenile birds that leave their natal sites for new temporary sites prior to actual migration, or to look for potential breeding sites. While I couldn't find any articles specific to post-breeding dispersal, I did find an article (1) that shows a model of potential dispersal among raptors
Looking at Dave's photos his birds appear to be juveniles. Of my photos from the day all of the birds I photographed also all appear to be juveniles, that is, I did not see any adult birds with red tails.
Mark responded with a note that another 49 RTHA's were seen in Ludington today, as well. Incidentally, he also mentioned that Braddock Bay conducts a late summer hawk count and had tallied 500 RTHA on 8/8/2019! (http://hawkcount.org/month_summary.php?rsite=353).
Since most fall hawk count sites report the majority of their Red-tailed Hawks migrating in late September through November the question is raised as to what is being observed now in mid-August. I have no data to back up my assumption, but I'm inclined to suggest that this may be Natal Dispersal (Natal dispersal is movement of an individual from its birthplace to place of first reproduction, whereas breeding dispersal is movement between breeding seasons from one breeding place to another (2)) by young Red-tails to pre-migration staging areas? This seems to be supported by a note from Josh who provided the following:
Mark responded with a note that another 49 RTHA's were seen in Ludington today, as well. Incidentally, he also mentioned that Braddock Bay conducts a late summer hawk count and had tallied 500 RTHA on 8/8/2019! (http://hawkcount.org/month_summary.php?rsite=353).
Since most fall hawk count sites report the majority of their Red-tailed Hawks migrating in late September through November the question is raised as to what is being observed now in mid-August. I have no data to back up my assumption, but I'm inclined to suggest that this may be Natal Dispersal (Natal dispersal is movement of an individual from its birthplace to place of first reproduction, whereas breeding dispersal is movement between breeding seasons from one breeding place to another (2)) by young Red-tails to pre-migration staging areas? This seems to be supported by a note from Josh who provided the following:
Something to ponder from one of the Mackinac Straits ambassadors Ed Pike…
Every year in mid-August I start seeing mostly immature Redtails moving through the area. (I have been seeing them this year also) I am sure this movement depends completely on weather patterns. I have always thought it is mostly young Red-tails moving around (post breeding dispersal). This also coincides with the time that I start getting calls on "injured" Hawks, normally turns out to be immature Redtails which are starving to death.
Every year in mid-August I start seeing mostly immature Redtails moving through the area. (I have been seeing them this year also) I am sure this movement depends completely on weather patterns. I have always thought it is mostly young Red-tails moving around (post breeding dispersal). This also coincides with the time that I start getting calls on "injured" Hawks, normally turns out to be immature Redtails which are starving to death.
The interesting question is, when does post breeding dispersal turn into migration?
This August movement seems to happen when a cold front moves down from the north to northwest and as with migration they move ahead of the front. I do not believe it happens with enough regularity to justify paying a counter to start in early August. It is similar to spring when through mid to late June, on some days there will be 10's to 100 or so immature raptors, mostly Redtails and Broadwings, still moving north across the Straits, but only on certain days with the right conditions which are not regular or predictable.
With thanks to all, its amazing what you can learn about hawk migration in a single day. Even when that day is still weeks away from fall migration season! Keep looking up.
References:
1. https://bioone.org/journals/Journal-of-Raptor-Research/volume-43/issue-2/JRR-08-33.1/Broadening-Our-Approaches-to-Studying-Dispersal-in-Raptors/10.3356/JRR-08-33.1.full
2. P. J. Greenwood 1980. Mating systems, philopatry and dispersal in birds and mammals. Anim. Behav 28:1140–1162. Google Scholar
3. https://bioone.org/journals/journal-of-raptor-research/volume-49/issue-1/jrr-14-54.1/Northward-Summer-Migration-of-Red-Tailed-Hawks-Fledged-from-Southern/10.3356/jrr-14-54.1.full
4. https://www.hawkmountain.org/raptorpedia/hawks-at-hawk-mountain/hawk-species-at-hawk-mountain/red-tailed-hawk/page.aspx?id=460
5. https://birdsna.org/Species-Account/bna/species/rethaw/introduction
1. https://bioone.org/journals/Journal-of-Raptor-Research/volume-43/issue-2/JRR-08-33.1/Broadening-Our-Approaches-to-Studying-Dispersal-in-Raptors/10.3356/JRR-08-33.1.full
2. P. J. Greenwood 1980. Mating systems, philopatry and dispersal in birds and mammals. Anim. Behav 28:1140–1162. Google Scholar
3. https://bioone.org/journals/journal-of-raptor-research/volume-49/issue-1/jrr-14-54.1/Northward-Summer-Migration-of-Red-Tailed-Hawks-Fledged-from-Southern/10.3356/jrr-14-54.1.full
4. https://www.hawkmountain.org/raptorpedia/hawks-at-hawk-mountain/hawk-species-at-hawk-mountain/red-tailed-hawk/page.aspx?id=460
5. https://birdsna.org/Species-Account/bna/species/rethaw/introduction
Leelenau State Park - Hiking Trailhead, Leelanau, Michigan, US
Aug 14, 2019 10:30 AM - 12:30 PM
Protocol: Traveling
6.0 mile(s)
Checklist Comments: Clear skies, winds 10-20 mph from SE;
14 species
Ring-billed Gull (Larus delawarensis) 6
Herring Gull (Larus argentatus) 6
Broad-winged Hawk (Buteo platypterus) 3 soaring overhead among larger kettles of Red-tailed Hawks. Long, pointed wings and wide tail stripes distinguished them from Red-tails.
Red-tailed Hawk (Buteo jamaicensis) 140 After receiving an e-mail earlier in the day from Mark Wloch and Dave Dister, who had reported a RTHA migration involving 200 birds yesterday in Ludington, I was surprised to see another migration push this morning between 10:30 - 12 pm. Birds were moving high in the sky and seen only against the white cumulus clouds. Kettles of 20-30 birds at a time were streaming from the SE to the NW and Lake Michigan shoreline. These birds were ID'd by the palatial bars that are exclusive to Red-tails, but also displayed large transparent windows in the their primaries (same as reported by Dave Dister). Red-shouldered hawks were not seen, but 3 broad-winged hawks were among them. Photos taken and will be uploaded later. Discussion online raised question if this is a post-breeding dispersal, but numbers seem too high. Some historical records suggest migration push in mid-August by some buteo species.
Hairy Woodpecker (Dryobates villosus) 1
Eastern Wood-Pewee (Contopus virens) 1
Black-capped Chickadee (Poecile atricapillus) 2
Tufted Titmouse (Baeolophus bicolor) 6
Red-breasted Nuthatch (Sitta canadensis) 1
Gray Catbird (Dumetella carolinensis) 1
American Robin (Turdus migratorius) 1
Cedar Waxwing (Bombycilla cedrorum) 6
Song Sparrow (Melospiza melodia) 2
Nashville Warbler (Leiothlypis ruficapilla) 1
View this checklist online at https://ebird.org/checklist/S5
This report was generated automatically by eBird v3 (https://ebird.org/home)
Aug 14, 2019 10:30 AM - 12:30 PM
Protocol: Traveling
6.0 mile(s)
Checklist Comments: Clear skies, winds 10-20 mph from SE;
14 species
Ring-billed Gull (Larus delawarensis) 6
Herring Gull (Larus argentatus) 6
Broad-winged Hawk (Buteo platypterus) 3 soaring overhead among larger kettles of Red-tailed Hawks. Long, pointed wings and wide tail stripes distinguished them from Red-tails.
Red-tailed Hawk (Buteo jamaicensis) 140 After receiving an e-mail earlier in the day from Mark Wloch and Dave Dister, who had reported a RTHA migration involving 200 birds yesterday in Ludington, I was surprised to see another migration push this morning between 10:30 - 12 pm. Birds were moving high in the sky and seen only against the white cumulus clouds. Kettles of 20-30 birds at a time were streaming from the SE to the NW and Lake Michigan shoreline. These birds were ID'd by the palatial bars that are exclusive to Red-tails, but also displayed large transparent windows in the their primaries (same as reported by Dave Dister). Red-shouldered hawks were not seen, but 3 broad-winged hawks were among them. Photos taken and will be uploaded later. Discussion online raised question if this is a post-breeding dispersal, but numbers seem too high. Some historical records suggest migration push in mid-August by some buteo species.
Hairy Woodpecker (Dryobates villosus) 1
Eastern Wood-Pewee (Contopus virens) 1
Black-capped Chickadee (Poecile atricapillus) 2
Tufted Titmouse (Baeolophus bicolor) 6
Red-breasted Nuthatch (Sitta canadensis) 1
Gray Catbird (Dumetella carolinensis) 1
American Robin (Turdus migratorius) 1
Cedar Waxwing (Bombycilla cedrorum) 6
Song Sparrow (Melospiza melodia) 2
Nashville Warbler (Leiothlypis ruficapilla) 1
View this checklist online at https://ebird.org/checklist/S5
This report was generated automatically by eBird v3 (https://ebird.org/home)
