Loon Ages: What do we really know?

If you read the posts of the chatters on YouTube, you may see a discussion about how the female is “26 years old” or “much older than the male.” So how do we know that? The answer is we don’t know. What the chatters are doing is taking an estimated minimum age and considering it to be the true age. More than likely, that is not the case.
The female on this territory was banded as an adult in 1998. The male was banded as an adult in 2014. So we can do the math and calculate that the female has been around for at least 21 years and the male for at least 5 years.
And we can adjust for what we know about the general life history of loons. After hatching and spending the summer on it’s natal lake, a young loon will fly to the ocean and remain there until near the end of its third year, when it will finally molt into an adult plumage and fly to the lakes of New Hampshire, looking for a productive territory it can move into. Since these two loons were banded as adults, we can add three years and calculate an absolute minimum age: 24 for the female and 8 for the male.
We also know that it’s not easy for a young loon to get a territory. Most times, the loon needs to fight to get it. And then there’s a learning curve to mating and nesting. The more experienced loons are more likely to nest and hatch chicks. So the rule of thumb is that by the time a young loon manages to get on a territory and actually hatch a chick or two, it will be five or six years old. So the chances are good that the female is at least 26 and the male is at least 10.
But is the female really older than the male? We have no way of knowing. Seeing that the female is approaching the maximum known age for a common loon (early thirties) statistical theory would say she is probably older than the male. But that’s what we are dealing with: maybe and probably.
Every now and then, we get a chance to capture a chick that is large enough band. We call them HY (hatch year) loons. For those loons and only those loons we can assign an exact age. HY banded loons are extremely valuable because we get to track them for their entire lifetime and we can learn more about dispersal behavior. But to fit a band to a chick it needs to be at least a couple of months old so that we’re sure the band won’t constrict the leg as the loon grows. But to catch a two or three month old loon is not an easy task. We take them as we can get them.