When Numbers Get Serious
How accurate is that Hawk Ridge Blue Jay count?
(Listen to the radio version here.)
I've heard from several people asking how anyone can possibly, with any accuracy, count 78,499 Blue Jays—this fall’s Hawk-Ridge total through October 5. How do we know they’re not counting the same jays over and over when so many are pigging out in oak trees and at bird feeders in nearby residential areas, going this way and that?
From my own neighborhood under Hawk Ridge, I sometimes see hundreds of Blue Jays on good migration days, but there’s no way I could possibly make a reasonable count. At any given moment, some may be in my feeder while others are in trees, flying overhead, arriving, and departing. And yep—except for the ones high above, they’re going every which way. When leaves are off the trees, I can see the Main Overlook from my yard, but all the foliage right now cuts my view to a relatively small wedge of sky and makes counting the birds in trees impossible.
At Hawk Ridge, no one is trying to identify birds hidden in trees—their job is to count migrants. The Main Overlook stands at an elevation of 1,226 feet, and the drop to my neighborhood is abrupt—my yard, 0.92 miles away as the Blue Jay flies, is more than 500 feet lower, with the hugest drop off right below the Main Overlook. My neighborhood gently slopes toward Lake Superior, its surface elevation about 600 feet.
Counters at the Ridge have an unobstructed view of the sky and much of the area below the Ridge above the tree line, spanning from east-northeast through east, southeast, south, southwest, west, and west-northwest. From the fairly new counting platform, they can also see further out in the more northerly directions. I'm sure they miss virtually all the Blue Jays coming into and leaving my yard almost a mile away below tree top level, but many of the jays I can see flying high overhead without stopping here are visible from up there, too. And those high-flying jays are all moving in a generally southwest direction to clear the lake.
Blue Jays are not strong flyers. They move in loose flocks and seem to travel in bursts of a mile or two at a time. It's only Blue Jays hanging out in a small area for a while who move every which way, and they tend to stay at or below treetop height. At Hawk Ridge, jays coming in from the northeast often land in the tree stand just before the main overlook to rest and feed. The counters can safely ignore them until they take off, when they’ll strike out overhead.
It's relatively easy to count moving Blue Jay flocks because in flight, they’re direct and fairly slow. A flock may be long and wide, but individual birds tend to stay in the same positions as they move along, unlike the much more swirling flocks of finches, waxwings, and blackbirds. And again, they’re all heading pretty much south-southwest to clear the western tip of Lake Superior.
When I was one of the emergency auxiliary backup counters at the Ridge in the 80s and early 90s through when Frank Nicoletti became the counter, we had one official counter (usually Molly Evans) and sometimes, on busy days, a helper or two. Now there are virtually always multiple counters as well as that new platform providing a significantly better view away from where visitors gather and distract. I was a very competent counter, but as with all human endeavors, from science to sports, people are always making advances. The skills I had three decades ago have been vastly surpassed by the skills of the current counters, both in terms of quick, accurate identifications and well-coordinated, improved counting methods.
So that count of 78,499 Blue Jays is a very close approximation of the number of Blue Jays who migrated over Hawk Ridge through October 5. Of course, that is not the total number of Blue Jays who passed through Duluth this fall. That number is unknowable but significantly larger, including the many jays who approached the eastern part of Duluth lower than treetop height, flitting neighborhood to neighborhood or sticking close to the shoreline, and the jays who approached Duluth well west of the Ridge.
As with just about everything related to birds, I love how the more we learn, the more we realize we don’t know. The winter range of Blue Jays extends just as far north as their breeding range, and their breeding range extends just as far south as their wintering range, so many visitors at Hawk Ridge are surprised to learn that Blue Jays are a migrating species. And no matter how well we study them and how much we learn, no mere human can predict whether an individual Blue Jay will leave or stay in any particular year—many young birds migrate but many don’t, and some adults migrate some years and not others. As talkative as they are, Blue Jays are much better at keeping secrets than we humans will ever be at figuring them out.