The Oldest Known Common Loon in the World

by Damon McCormick
Common Coast Research & Conservation

The early morning of April 26, 2012 finds the male common loon the ABJ (ABJ stands for Adult Banded Juvenile) of F Pool shadowing the slow transit of his mate as she threads her way between islands dotting the eastern end of their territory. They are inspecting possible nesting sites. As she drifts toward the shoreline of a small hummock, his attention rises to a familiar silhouette soaring very high overhead: bald eagle. At much lower elevation an osprey is simultaneously crossing the pool with an ambitiously large branch in its talons, but it is only the eagle that garners his interest. He cocks his head to the left, fixes his distant antagonist with a tactical right eye, and decides against vocalizing a two-note wail of warning. The shallow northern perimeter of the pool is crowded with migrating ducks, and the ABJ shifts his focus toward a pair of mallards that have strayed into deeper, more open waters. He swivels, hunkers, submerges… ten seconds later the mallards, roughly 60 meters away, flush boisterously as the ABJ surfaces beneath them. A small group of nearby Canada geese take notice and move off wearily; a lone pied-billed grebe, also in the vicinity, sagely slinks toward the protection of shoreline cattails. The ABJ’s mate has continued her island inspections during his interspecific engagements, but as the figure of an in-flight loon suddenly appears low on the eastern horizon, she abandons the effort and swims briskly in his direction. The ABJ waits until the flyer is over F Pool airspace before unfurling his abrasive territorial bellow, the yodel. The length of his bark is proportional to the level of threat that he perceives, and in this instance he deploys a relatively short five seconds of vocalization. The overhead loon, who has briefly arrested the pace of his wingbeats in anticipation of a possible landing, reacts to the call by immediately resuming his cruising velocity and redirecting himself to the southwest. A moment later another yodel, conspicuously different in pitch from that of the ABJ, rises from the direction of E Pool’s eastern end. By the time a fainter yodel emanates from E Pool’s western end, the ABJ and his partner have already recommenced with their scrutiny of possible nesting sites.

The last of the audible yodels, from the E Pool West territory, belongs to the ABJ’s twelve year-old son, who hatched on F Pool in 2000, returned to the Refuge as an adult in 2003, and acquired E West in 2008. To the south of F Pool another son, a thirteen year-old, holds the C Pool South territory, and to the west a seven year-old daughter freshly occupies G Pool in her first season of territoriality. More distantly, forty miles to the west, a fourteen year-old daughter resides as the breeding female of Bunting Lake, in Alger County. A third son, hatched in 2001, held C-3 Pool for four summers before failing to return in 2011, a likely victim of botulism poisoning on Lake Michigan. A third daughter was recovered dead in April 2009 near Perdido Key, along Florida’s Gulf Coast, seven months removed from fledging F Pool as a juvenile. These offspring are but six of the twenty chicks that the ABJ and his mate have hatched at Seney since 1998. Although the loon passing over F Pool on this late April morning is not among the twenty, considerations of paternity would not influence the ABJ’s response to the prospective interloper: familial obligations end with a first-season juvenile’s Refuge departure for autumn migration.

Until such an embarkation, however, the ABJ distinguishes himself parentally. During the first six weeks after hatching, when a loon chick is most dependent and vulnerable, the average Refuge adult directly attends to his or her offspring with food and protection 78% of the time; at other moments he or she may be feeding on other parts of the territory, or even away from the pool altogether. In contrast, the ABJ directly attends to his young offspring 97% of the time. Similarly, while the typical Refuge parent spends 12.7 weeks with his or her chick(s) before undertaking migration, the ABJ devotes an average of 15.1 weeks (adults almost always depart for the season ahead of their fully-developed young; mothers more frequently leave first). Perhaps in consequence, he has successfully fledged 95% of his chicks compared to the Refuge average of 81%. And this efficiency has been coupled to stellar overall productivity: the ABJ has hatched 1.43 chicks per season against a rate of 0.86 for all Seney loons, who themselves are the most reproductively successful loon population in the Upper Midwest.

In early June, the ABJ will turn 25. He is the oldest common loon of known age in the world. Detailed observations of his life history have been enabled by a color-marking program that began in 1987, when the ABJ was a chick on G Pool, and that has subsequently banded and monitored over 250 Refuge loons. Although the main intent of the research has been to illuminate aspects of the species’ biology through the study of an entire color-marked population, an ancillary benefit of the work has been the agglomeration of data concerning specific birds that has, over time, assumed the contours of biography. In other words, in searching for truths about all common loons, along the way the research has stumbled upon truths about individuals such as the ABJ. On the morning of April 26, as he initiates his nesting effort for 2012, the odds are good – 86% based on past evidence – that come summer the ABJ will once again form a conspicuous, doting fatherly presence along the beginning of the Refuge’s Auto Drive.