A lot can happen in a short time, it seems. I have spent only three days in the study area so far, but already we — Joel, Eric Andrews and I, and our incredible citizen scientists Linda Grenzer and Al Schwoegler — have found 8 active nests. Considering the territories we have visited recently and those we have not, I estimate that about 15-20% of all pairs in the study area are already incubating. Clearly the pairs have shortened the window between ice-out and egg-laying in order to compensate for the very late spring this year. I suspect this is possible, in part, because females were able to recoup much of the energy consumed during spring migration by foraging for weeks along rivers in the study area, before their breeding lakes opened up. That is, the extra foraging time near their territorial home apparently compensated for the foraging time that would normally occur on their territory.

Territorial turnovers have been common this spring; many marked pair members from 2013 either failed to return in the spring or did return but were evicted from their territories. The evicted birds include a young “ABJ” (“adult banded as a juvenile”; meaning a loon we banded as a chick) male from Schlect Lake. This ABJ male, hatched on Fox Lake in 2005, produced two chicks, of which one fledged, in 2012. But in early 2013, the Fox ABJ had been replaced by another ABJ male, this one also hatched in 2005, but on McNutt Lake. In late 2013, the Fox ABJ was able to retake his territory (possibly after the McNutt ABJ left it) and lived there the rest of the summer. However, two days ago, Eric and I witnessed a nasty battle between the Fox and McNutt ABJs (now both 9 years old) that culminated in the exhausted and defeated Fox male taking refuge on shore to avoid further attack from the McNutt male. Quite a grim spectacle! It remains to be seen whether the Fox ABJ can recover, drag himself off of this tiny 25-acre lake and get on with his life.

While our problems pale in comparison to the desperate life-and-death struggle that the Fox ABJ is facing, this latest contest is troubling to us as well. You see, we have hypothesized that dangerous contests of this kind likely occur when very old males (with very little reproductive fitness to lose) roll the dice by battling to win a few more years on their territory rather than accepting displacement by a younger, stronger male. (This is termed the “terminal investment hypothesis”.) Naturally, we must use statistical tests on a large body of data before drawing any conclusions. Still, it was unsettling to see a vigorous young male — and one that doubtless would have many potential future years of reproduction ahead of him — suffer a life-threatening encounter that flies in the face of our pet hypothesis.