A wet few weeks in late April and early May sent a lot of water toward the St. Croix, ultimately raising the water several feet on the lower river. It felt like an old-fashioned spring flood after the past three years of drought, although with no significant threat to people or property.

I took advantage of the chance to explore some favorite floodplain — that flat area of islands and shoreline that is frequently submerged. It lets a canoeist or kayaker paddle between the trees and get up close to a lot of wildlife and other sights. It’s rich habitat, home to many types of plants and animals, from dragonflies to eagles. It’s only accessible like this every so often, and is worth the wait.

In the first five days of May, I managed to get on the river four days (I wrote about the first couple trips last week). I also got out for a couple walks along its bluffs. I went by myself, with friends, and with family. For a variety of reasons from convenience to curiosity, all the trips were based around the same relatively small stretch of river. Focusing on this one patch of interwoven forest and water let me see it in great detail, and also watch the subtle changes that happened everyday.

I don’t usually look for many warblers this early. Perhaps entirely erroneously, I always expect them in about the second or third week of May. My thinking is they’re primarily insect eaters, and it needs to get warmer before many bugs start showing up. So I was surprised to see so many last week. Perhaps it’s because of the warm winter and early spring, perhaps it’s because I haven’t seen what I wasn’t looking for before.

I was especially delighted to discover a pair of prothonotary warblers, who we saw two days in a row. The first day, they were deep in the floodplain, hopping around near the water, drinking and eating and calling. Prothonotary warblers like these dim forests, the sprawling silver maples spreading a thick canopy overhead, where direct light rarely reaches. The birds are such a bright yellow they appear illuminated, like splashes of pure sunshine in these shady environs.

Even in their winter habitat in Central America, prothonotaries prefer wooded swamps like this. They bring the feeling of tropical mangrove forests north with them each spring.

Prothonotary warbler (Greg Seitz/St. Croix 360)

The second day we came across the birds, they were flying back and forth from the rotting stump of an old tree, a snag sticking no more than six feet out of the water. Prothonotary warblers are one of the only warbler species that nests in tree cavities, and that’s what they were working on. On the trip to the nest, they carried bits of moss in their beaks, then went for more. The floodwaters below seemed dangerously high, but they would also keep potential predators away.

Other warblers observed included yellow, common yellowthroat, black-and-white, yellow-rumped, and Nashville. Each one a small a colorful blur bouncing around the trees.

There were also abundant red-winged blackbirds, some sandpipers, a green heron, bald eagles busy with chicks, and as ever, Canada geese and wood ducks, the sounds of sandhill cranes and song sparrows.

As birds arrived and departed, or staked out territories, as the waters rose and fell, the flowers opened and closed, the grasses grew. The tree leaves got a little bigger each day. The weather was everything from gloomy rain to bright sun, windy with big gusts to still and silent. The river rushed south with silent insistence.