The massive raptor migration through the Keweenaw, which clearly is most prominent at Brockway Mountain, is well known. What is hardly known at all is just where the raptors we see at Brockway are actually going. Brockway’s eastbound numbers are always much, much greater than the westbound numbers. Extensive observations at Manitou Island off the tip of the Keweenaw pretty clearly show that no large numbers of raptors cross Lake Superior there. So many of us Keweenaw people have come to the conclusion that the Brockway / Keweenaw raptors probably eventually move southwest toward Duluth and thus around the Big Lake. But just what are the patterns of raptor movement through the tip of the Keweenaw? Where are all those westbound birds that Brockway just doesn’t get? The Raptor Net idea was supposed to help answer those questions. At least twice in the past decades small groups of Keweenaw hawk and bird watchers arranged for a day or two of coordinated counts at various sites in the Keweenaw. This year we actually achieved six days of counts (28 April through 3 May) at three different sites. Of course the main site was Brockway and we also had observers on Rocky Ridge and also at Bete Grise beach. Each site was supposed to visually cover about one third of the Keweenaw. Brockway covers the north third, Rocky Ridge covered the middle third and Bete Grise covered the south. So we believed that most raptors moving east or west through the Keweenaw could be recorded by one of our sites. In addition to those mainland sites we had an observer out at Manitou Island for a full twelve days. Manitou is a major complicating factor in any study of Keweenaw raptor movement. Its pretty straight forward to count raptors, eastbound and westbound, at Manitou’s western tip. But the problem is that Manitou is almost like a storage battery for raptors. You don’t really know how many raptors are “on” the island. You can count birds coming from and returning to the mainland Keweenaw but you never really know how many raptors are just “on” Manitou. From our observations there we know that some days the number “on” Manitou is well over 1,000 and its possible the hundreds of raptors hang out at Manitou for several days. So Manitou really complicates any analysis of movement of Keweenaw raptors.
So how did we do? Did we find the missing westbound birds? We tried hard but we really didn’t find those westbound birds. The Bete Grise site did have more westbound than eastbound birds, as expected, but the numbers didn’t account for the large numbers of eastbound birds seen at Brockway. It seems likely that our six days just wasn’t long enough. We had reports of many hundreds of birds moving west at Bete Grise several days after our count period ended. Were those birds stored up over at Manitou for a few days and returned west after our count?
Here are the totals for the six day period:
Eastbound Westbound Total Rocky Ridge 412 365 777 Bete Grise 63 254 317 Brockway 2056 618 2674 Manitou 595 755 1350
I’d like to thank our volunteer observers : Mike Swaney, Wendy Sharp, Bill and Nancy Leonard, Bill Deephouse, Tom Rozich, Ruth Gleckler, Lynn Murphy, Catherine Andrews, Keren Tischler, Curt Webb, Phil Quenzi, Marj and Ray Krumm, Nancy Auer, Quentin and Emily(?) Sprenglemeyer and Arthur Green
P.S. - Manitou Island does have its data posted on HawkCount. But I have been lagging in my work and have yet to post the thousands of westbound raptors at Manitou from this spring. I’ll get to it soon. We had 2155 eastbound raptors and 3087 westbound at Manitou from 28 April through 9 May.