This has certainly been one of the more unusual spring migrations here. I mentioned last time that many of the insect-eating species of migratory birds seemed to be holed up in the Twin Cities area, their movements stalled by an extended period of cold weather and unfavorable winds.

Some species, like orioles and grosbeaks, were coming through in strong numbers because they are not as dependent upon insects, as are the warblers, vireos and flycatchers. That's my read at least on why these latter groups were so poorly represented here, when one can normally expect most of them after the middle of May. Janet and I searched for them in vain each morning through most of the month before retiring indoors to warm up and eat breakfasts that we would normally be eating on the deck.

Then, with the arrival of those 80-degree days, the dam burst.

On May 29, we were finally rewarded with a really nice "wave" or "fallout" of warblers. At first, they were mainly in the very tops of trees, where the early morning sun was warming up insects and spurring them into activity.

American redstarts and chestnut-sided warblers seemed to be everywhere (many of them more easily detected by their songs than by our fleeting glimpses of them as they moved rapidly through the foliage).

Other species we were pleased to see that day were the Canada, magnolia, Wilson's and blackburnian warblers. The Canada warbler, with its yellow underparts crossed by a necklace of black streaks, has always been one of our favorites.

But the "best of show" is inevitably the blackburnian, with its stunning flame-orange throat contrasting with mostly black upperparts and a large white wing patch. Check it out in your field guide if you don't already know it.

The warbler family, which includes about 30 species native to Minnesota, is as diverse and beautiful as any other family of North American birds. Your best chance of seeing many of them in full breeding plumage is when they are passing through in the spring.

The next day numbers of migrants were not as impressive, but several new species arrived, including red-eyed vireos. Though you don't see them unless you really try, these vireos are one of our commonest summer birds and they sing their monotonous series of musical phrases throughout the day.

Through June 3, when I wrote this column, other late migrants were showing up daily. Flycatchers were prominent among these new arrivals. Our favorite is the olive-sided flycatcher, which utters its loud "Hip, Three Cheers" (or, if you're from Wisconsin, "Hic, Three Beers"!) from a high, exposed perch.

The species that don't remain to nest will be long gone after the next few days. We're glad we didn't give up trying this year after the frustratingly long migration drought. Hopefully next year's migration will be more prolonged, allowing more opportunity for all birders to study and continue to learn them.