The birds faithfully arrived each spring as soon as the ice was gone. They lingered in the fall until the woods were empty of bird song and filled with the crunch of fallen leaves.

The loons did not nest, though, as far we could tell. Young loons never were seen.

Cabin owners eventually built and placed a nesting platform on the lake. The loons responded with a nest that failed for reasons unknown.

The platform was modified, and anchored in a different part of the lake. There were eggs in the nest that year. Unfortunately, it too was abandoned, well into incubation.

Those of us keeping an eye on the loons feared that boat traffic near the nest on Memorial Day weekend was too much for the parents, this on a lake where motored boats were prohibited.

We were pleased and surprised when the loons produced yet more eggs that season and began incubation again.

On a Saturday morning in mid-June a bald eagle was seen on the nest. The eagle was not sharing incubation duties. It was eating the eggs, dipping its head in and out of the nest. The eagle’s bill dripped.

The bird bent from the nesting platform and swished its beak briskly through the water. A three-year-old bird just beginning to show white on its head, it then flew away.

Throughout the attack, the would-be parent loons circled restlessly in the water about 30 feet from the nest. When the eagle took wing, the loons screamed loudly and disappeared underwater.

They later were seen quietly swimming and foraging in deeper water in another part of the lake.

Some researchers believe that common loons can live as long as 30 years. Like all birds, one of their purposes is to replace themselves, keep loons on the water. Over the years we learned that not all loons form pairs, not all pairs nest, and not all nests are successful. Nor do all hatched chicks survive.

Figures from Minnesota loon surveys show that one chick per two pairs per year is a rough average of nesting success.

Loons live a long time by bird standards, however. They have many seasons in which to replace themselves before they die. Persistence pays.

A former neighbor in Wisconsin sends us loon reports from “our” lake. This summer the pair built its nest on a beaver lodge about 100 yards from our former dock. (Wish we were there!) The nest this year, with eggs, was fine until rains raised the lake level and ruined the nest.

This pair of nesters, if indeed it’s the same pair we watched, with luck has years ahead of it to try again. These birds obviously and thankfully are hard to discourage.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com.