After a Slow Start, A Good Breeding Year

Since snow and ice lingered far too long this spring, loons were late to nest in northern Wisconsin. The lateness of the season has also reduced opportunities to renest after early nest failures. There was simply limited time for pairs to weather four weeks of incubation and still rear the chicks to a point where they could learn to fend for themselves and make their way to Florida. Add to the narrow window this year the mishaps that cost us young chicks on several territories….and I was beginning to sweat.

But my fears of another off-year for nesting success in the Upper Midwest loon population have not been realized. A relatively short period of black fly abundance has helped immensely. As our recent paper showed, abandonments from black fly harassment are a good predictor of nesting success; that pattern has continued in 2018. So it seems likely that this year will break our four-year breeding slump.

Here are the numbers. As of July 4th, we had an estimated 48 breeding pairs in our study area with a chick or chicks. Eighteen (give or take a few) were still on nests, of which over half will produce chicks also. That leaves us with roughly 60 loon pairs with chicks. A handful of the 60 pairs will lose their chicks before 8 weeks; in addition, though, we will make roving visits to non-study lakes within and just outside the study area and find about 6-8 more pairs with chicks. When the dust has settled, we should end up with a number of pairs with chicks that is very close to the 65 successful breeding pairs we were able to band in 2013. That fact is worthy of note, because 2013 was both a year in which our procedures and lake coverage were similar to this year, and the last solid year of breeding. So we can all breathe a great sigh of relief — and enjoy Linda’s cool photo of the freshly-hatched chick on Muskellunge Lake and the female, with moist eggshell fragments still adhering to her breast.