Monitoring Waterbirds from Manitou Island and Au Sable Point

Joseph Youngman, via Copper Country Audubon, has investigated waterbird migration from more of Lake Superior’s islands and promontories than anyone I know. Last year, Youngman had an idea: to deploy simultaneous, standardized counts during October 2020 from Manitou Island (offshore the tip of the Keweenaw) and Au Sable Point (in Pictured Rocks west of Grand Marais) while WPBO’s count was also in session. The goal was to develop a month’s snapshot of flightlines and species composition in regard to waterbird migration at these sites, and this would be on behalf of Copper Country Audubon, which has provided over $70,000 for Lake Superior migratory studies since 2010. Tim Baerwald and I (with assists from Youngman, Captain Travis from Keweenaw Charter Fishing, and my partner, Tripp) would be the executors. I’d start on Manitou, Tim would start at Au Sable; two weeks in, we’d swap stations. That was the plan. 

However, Lake Superior has the final say on plans like these, and early autumn 2020 was stormy. Plans changed with the lake’s decrees: Tripp and I were rushed to Manitou two days ahead-of-schedule, and Tim left Manitou early, on Oct. 20. For the remainder of the month, he counted from Hebard Park (on the Keweenaw three miles west of Copper Harbor). 

Though geographic distance is relatively minimal, waterbird migration disparities between these eastern and central Lake Superior sites are distinct. For example, Long-tailed Duck traveling west pass Au Sable Point in great numbers on the same days that eastbound long-tails peak at Whitefish Point. Redhead have seemed more numerous at Keweenaw sites than at Whitefish. Detailed descriptions of numbers and flightlines from this project can be found at www.coppercountryaudubon.org/manitou-island. Here, I will summarize the sites and our observations. 

Manitou

Manitou Island lies about three miles offshore the Keweenaw. It’s large — roughly a thousand acres — and covered in dense boreal forest. Mammal diversity is low, with snowshoe hares (abundant) the largest species we noted; we had no human visitors. There, we stayed in a 150-year-old lighthouse that had no heat, no running water, and no electricity. What it did have was mice — triple digits of them, actually. And, in the scramble to catch the boat, we’d forgotten to pack mousetraps…even so, we loved Manitou. There, life was reduced to simple survival rhythms: fetching water and keeping warm, and occasionally fishing for sustenance. Existence was uncomplicated but intentional. 

Manitou’s weather made typical WPBO conditions seem bucolic. Gale warnings were the standard forecast, and this stalled migration for much of our time there. Several days, I struggled to tally even just 100 migrating waterbirds, which I hadn’t expected — October is the month when Superior’s highest-volume flights occur. At night, I’d bed down (inside a tent, inside the lighthouse — it was the only way to prevent 3 a.m. mouse jaunts across my face). I’d imagine legions of ducks piling up somewhere to Manitou’s northwest, waiting for the weather to break. Then, I’d be awakened by various parts of the lighthouse rattling in the wind. 

When I woke on Oct. 13, I’d seen just 4,875 waterbirds the entire stint. This morning — the last before our departure — it was finally calm. The sky lightened, revealing the most intense flight I’ve ever counted. Tripp brought me coffee about a half-hour in and stayed for most of the day; he spotted flocks, which I then deciphered as best I could. Most were Aythya (scaup and Redhead), and Aythya identification is challenging — differences are subtle, and the birds travel in multi-species masses aptly described by Seawatching as “prone to disintegrate into chaos.” Attempting to keep up was mind-numbing, and I never got around to drinking the coffee Tripp brought. The day’s tally was 13,339 — and I know I was missing birds. Tim, counting at Au Sable, had a great flight this day as well, logging around 12,000, while Whitefish Point tallied around 7,000. 

The morning after this incredible flight, we waited on the dock for Captain Travis. The wind was building again, and our scheduled pick-up time came, then went. A Short-eared Owl was coming off the lake, hitting first land after so many miles with just water beneath — always poignant to see. But I was uneasy. Tripp turned on the radio to hail Captain, and we caught the NOAA forecast, “…by Wednesday night, seas building to 11 feet…” It was Wednesday morning. So, when Captain Travis rounded the island a few minutes later, we were quite relieved. To experience Lake Superior waterbird migration on a remote island was to experience waterbird migration in a further dimension. Weather systems dictated our comings and goings in the same manner they did the birds I was there to count; the degree of separation between us lessened.  

Au Sable

Au Sable Point is in Pictured Rocks National Lakeshore, somewhat west of Grand Marais. Relatively speaking, Au Sable is not far west of Whitefish Point — roughly 55 lake miles. Because Whitefish Point’s fall migration is eastbound, it seems logical that waterbirds passing Au Sable would also be flying east. Au Sable’s numbers for October were very close to WPBO’s (49,493 and 55,868, respectively), but migration at Au Sable was bidirectional: 29,774 birds flew east (EB); 19,749 flew west (WB). In some species, for example Northern Pintail and Long-tailed Duck, the disparity was particularly evident: We logged 921 WB pintails at Au Sable (and 188 EB) in October — WPBO recorded just 384 (EB). 

The pintail push at Au Sable happened late, with two dense flights (412 on Oct. 25 and 404 on Oct. 21). Most of the pintails I’ve observed at WPBO travel in small flocks and often mix with other dabblers, but at Au Sable, flocks were large (n = 40–75) and typically homogenous. Neither Tim (further west) nor WPBO saw significant pintail movement, and still, I wonder: Where did my birds stage? Where were they cutting inland? Where are they headed? Lake Michigan to the Mississippi to the Gulf, even? 

When the Long-tailed Duck peaked at Au Sable, they were also peaking at Whitefish; our big days happened simultaneously. However, where long-tails at Whitefish flew east, most of Au Sable’s flew west. (And long-tails are much less prevalent on the Keweenaw. Tim, still on Manitou for the first of the big Au Sable (n = 1,652) and Whitefish (n = 712) long-tail days, had just 28; a 2014 count at Hebard Park recorded 418 to Whitefish’s 27,396…) In total, this October, Au Sable had 15,292 WB (and 1,418 EB) Long-tailed Duck; Whitefish had 23,158. It is evident that WPBO’s long-tails and Au Sable’s long-tails leave the Lake Superior basin in different locations. Presumably, the WB birds at Au Sable were cutting inland to do this; when Skye Haas and Gary Palmer noted, during Au Sable’s peak flight days, high flocks of long-tails coming south overland at sites near upper Green Bay, this pins a possible route on the flightline map. Regardless, an incredible amount of Long-tailed Duck traverse Lake Superior during these few days in late October, passing the count sites in gorgeous flocks of several hundred. It is a powerful migration event I recommend you seek out. 

The disparities between the direction of travel at Whitefish Point, Au Sable, and Manitou left me with so many questions: Where do these birds stage? Where do they cut inland? Where are they headed? Why do some birds, like Long-tailed Duck, exhibit intraspecific route differences, while others, like Redhead, are more prominent at Manitou (n = 3,031) than Au Sable (n = 977) or WPBO (n = 834)? These are the questions that keep my fires burning…perhaps, perusing these tables will inspire questions of your own.

~by Alison Vilag

The Manitou section of this article appeared in the 2021 Winter Jack Pine Warbler. Featured photo: The lighthouse on Manitou Island that housed the waterbird counters during their stay. Photo by Alison Vilag.

Fall Count Data

Rarities

*Species where documentation is solicited by the Michigan Bird Records Committee (MBRC)

Landbirds observed coming south off Lake Superior at Manitou and Au Sable 

Prominent species during October counts (east and west refer to eastbound and westbound totals at Au Sable)

*WPBO numbers were taken from WPBO’s Dunkadoo

*Manitou Island’s totals consist of counts on Manitou (Oct. 1–13 and Oct. 15–20) and Hebard Park (Oct. 21–31)