Dozens of territorial pairs in our study area are now on nests. Several pairs have failed. Early indications are that failures this year will be caused mainly by predation. Raccoons are the most frequent culprit, according to work done by the DNR in our region using nest cameras. In spite of the havoc wreaked by raccoons, we still hope for a high rate of hatch.
Territorial visitors are a common sight on breeding territories these days. They will become increasingly common as the season wears on. Many lake residents wonder who these territorial intruders are and what they are doing. These loons are not, as many folks surmise, chicks that have matured and are returning to visit their parents. They are true territorial intruders — individuals that are young and have never possessed a territory or are older and had one but were booted off of it by another loon. Intruders intrude to learn about the territory and its defenders, primarily because they hope to usurp the territory by force on this or a subsequent visit.
One interesting pattern that we have seen in the last few years among intruders is a higher rate of long-distance intruders. For example, On Big Carr Lake a few days ago, we saw a female from Moon Lake in Vilas County. This is a bird banded by my collaborator, Mike Meyer of the DNR. More recently I identified a 5 year-old intruder from Powell Marsh: again, this was a DNR-banded bird from up in Vilas County. Of course, we value every banded intruder, as each gives us an opportunity to track a loon’s movements and the strategy it uses to gain a breeding slot. But the long-distance intruders are especially valuable, because they are chiefly females, which disperse much longer distances than males, on average, and which, therefore, we have learned less about.