We are not the only people who study loons. In fact, dozens of researchers from Iceland to Montana…from Alaska to Massachusetts…and from British Columbia to Newfoundland have done so. And that is to say nothing of loon study that occurs on the wintering grounds.
Loons are, of course, engaging animals. It puts a spring in my step just to tell people that I study them. And the same is true of dozens of undergrads, Masters’ students, and loon enthusiasts who have chosen to spend time with these odd and fascinating birds.
But spending time with loons and gaining useful knowledge about them are two different things. Much of the basic information about the life-history of the species — where they nest; when they arrive on lakes in the spring; what their predators are — has been understood for some decades. So folks who observe the behavior of loons during the breeding season, even with a keen eye, have a hard time contributing to our knowledge of the species.
There is an exception. Marking of animals for individual identification throws open the door to an abundance of exciting and useful research questions. Once we had marked a few dozen loons in the 1990s and begun to follow their lives closely, we quickly put to rest the abiding — though scientifically implausible — legend about the species: that they mate for life. We now know that a typical adult has several different mates during its lifetime. More profoundly, we now know that loons are decidedly unromantic. A loon’s bond is to its territory, not its mate. When loons fight, they fight to retain their ownership of a territory — and to remain paired with whatever individual of the opposite sex has succeeded in maintaining its own bond with the same territory. Having loons banded has forced us to recognize the shocking fact that established breeders whose mate is evicted by a competitor simply pair quickly with the competitor, leaving their previous mate on its own to cope with the loss (on a new territory).
Marking of loons also exposed a peculiar finding about the species: that males choose the nest site. Since we have breeding pairs marked, we have measured statistically how males take the lead when pairs are nest-searching. More to the point, we have shown that the disappearance of a male breeder causes a territorial pair to “forget” nesting locations that they used successfully in the past.
While color-banding of loons is immensely valuable for behavioral study, it is even more so for monitoring populations. This is easy to understand. Once you start marking animals and systematically working to resight them, you learn at what rate they return annually to breeding territories. Instances of return or failure to return allow us to construct a population model to estimate adult survival. And if resighting efforts take place within a tight cluster of study lakes that are visited regularly, a researcher can refine the population model by accounting for those frequent cases wherein an adult loon failed to return to its lake not because of mortality but because a competitor evicted it and forced it to move to a new breeding lake nearby.
In fact, it is our intensive — almost obsessive — efforts to relocate adults lost from their original territories that makes our study methods unique. The obsession extends to loon chicks as well. That is, we search far and wide to find the breeding territories of loons that we banded when they were four to six weeks old. To date, we have discovered 183 chicks that matured and settled on territories 4 to 11 years later. These data further improve the population model, because they permit us to estimate survival of chicks to adulthood. Linda found our latest case of settlement by an adult-banded-as-chick on Manson Lake just yesterday. She tells me that this is the first instance in which she took a photo of a chick (above photo of the 2013 family on Jersey City Flowage) and then snapped another of that same loon after it had returned as a territorial adult (see photo below of this eight year-old yodeling yesterday on Manson Lake).
We are still going strong in Wisconsin. Each year that passes improves our known-age data on adults and chicks banded as long ago as 1993. This year, though, through a brand new partnership with the National Loon Center in Crosslake, we are bringing our technique of intensive mark and resighting to Minnesota. In the next several years, we hope to share better tidings with lovers of loons in central Minnesota than we shared recently with loon enthusiasts in Wisconsin.