The two-year olds have done it again. At an age when most loons are loafing, feeding, staying out of trouble, and just trying to survive, a second two-year-old has shown territorial pretensions. This time, the loon is a female. This time, the territory is in our Minnesota Study Area.
The discovery occurred three days ago on Pig Lake. Although I always smile at its undignified name, I was a bit sad to visit Pig, because neither pair member from 2022 had returned this spring. This fact reminded me of the generally poor return rate in Crow Wing County and my growing concern for loons in Minnesota. So as I gazed through binoculars at the whitecaps on Pig, I braced myself for what more bad news the lake might have to offer.
But among the four loon heads bobbing about in the surf, I was thrilled to spot a banded loon. This bird was one of a pair that dived in close synchrony off of Black Pine Resort. “One of the missing pair members is back!”, I whispered to myself, hopefully. Further observation dispelled that notion. The loon’s right leg showed two colored leg bands. Since all loons banded as adults get a metal band on the right leg, two plastic bands on the right leg meant that I was not watching one of the missing pair members, but instead observing an “ABJ” (adult banded as juvenile). That is, we had banded this loon as a chick.
Two possibilities leapt to mind. This bird might have been a one-in-a-million, 200-mile disperser of undetermined age from the Wisconsin Study Area, where we have been banding adult loons and chicks since time immemorial. Almost equally unlikely, the ABJ might have been one of our first crop of Minnesota chicks banded in 2021. The plot thickened as I compared the size of the ABJ and its mate. The banded bird was clearly smaller. I was looking at a rare female ABJ!*
My efforts to nail the ABJ’s color bands from my solo canoe were not immediately rewarded. I loosely followed the foraging pair, bobbing and spinning about comically amidst the churning waves and boat wakes. Eventually a moment came — forty minutes into my chaotic paddle — when the ABJ and I were carried to the crests of adjacent waves and the bird raised its legs clear of the water. I confirmed that the bird was blue over auric red on the right and red over silver on the left. “B/Ar,R/S”, my notes revealed, was marked as a chick on Ossawinnamakee – Muskie Bay territory on 18 July 2021. So this was indeed a two-year-old female hatched a short distance from Pig.
Like the two-year-old male who is trying to settle on his natal lake in Wisconsin (pictured above in Linda Grenzer’s photo), B/Ar,R/S is special in two ways. She is not only the first chick we banded in Minnesota and have now reobserved as an adult. She is also less than half the age of the previous youngest female ever observed to settle (even for a day) on a territory. (That female was a Wisconsin five-year-old.) Since females settle at older ages than males, her pairing up is even more surprising than settlement of the two-year-old male in Wisconsin in the photo.
What are we to make of this astonishingly early territorial behavior by separate individuals in Wisconsin and Minnesota this year? Nothing at the moment, I think. Two rare events do not constitute a pattern. But those who follow the blog closely might recall that a decline in the population of floaters — mostly young adults not yet settled on territories — is one of the hallmarks of the current downward turn in the Wisconsin population. If we continue to see two- and three-year olds compete for territories in ways they did not 15 years ago, we will have to regard it as another indication of a limited pool of nonbreeders in Minnesota and Wisconsin** — and, hence, further evidence of a broad decline in the Upper Midwest loon population.
*most loons banded as chicks return at three or four years of age. Among those few that return at age two, very few are female. Indeed, about 3/4 of all ABJs we see are males, because males do not disperse far from their natal lakes to breed.
**The logic is simple here. If there are few young adult floaters (usually 4-, 5- and 6-year olds) in a population competing for territories, then even very young floaters (2- and 3-year olds) might be able to acquire one, despite their generally lower competitive ability and aggressiveness.