Hummingbird nests are the Golden Fleece of the avian world. I've only found two in many years of searching and in each case, it was the mother bird flying to or from a branch that alerted me to her nest nearby. They're so small, so well camouflaged and so cleverly hidden that few of us ever encounter them.

That's why Don Severson, whose photos frequently appear on this page, was excited when a friend called with news of a hummingbird nest in a neighbor's oak tree. Even though the site was more than 100 miles from his home, Severson was so eager to observe a nest up close and take photos that he drove the distance every five days. Arriving just after the female had laid her two bean-sized eggs, he chronicled the chicks' lives as they hatched, grew and then fledged.

For such tiny birds, female hummingbirds are the Little Red Hens of nesting season. Each builds a nest and raises a set of twins entirely on her own. The female sits on her eggs for about two weeks, taking breaks to feed herself and preen her feathers. Once hatched, the chicks spend up to three weeks in the nest, while their mother makes many trips a day to gather their food.

She catches gnats, fruit flies and small bees on the fly, sometimes pulling them from spider webs. To lap up nectar she zips between cardinal flowers, honeysuckle, bee balm, trumpet creeper and red morning glory, then pumps a slurry of sweet liquid and tiny insects down her chicks' throats.

Add a gram here and another there, and hummingbird chicks would quickly outgrow their tiny nest but for the ingenuity of their mother, who built it from plant down bound together with spider webbing. This latter material is elastic, expanding as the chicks grow, so the nest continues to encircle them until they're ready to leave.

Severson found the experience mesmerizing, driving 200 miles round trip and spending several hours on each visit for about five weeks. He initially took photos from a blind, but then realized the mother bird wasn't bothered by humans. She didn't even mind when he climbed a stepladder to snap images inside the nest.

"I realize that not many people get to see a hummingbird nest," says Severson, a retired high school English teacher, "but the irony of this story is that I got to see it two years in a row." The mother bird returned to the same oak tree the next year, so he was able to watch the twins grow up from "little fuzz balls" but missed their fledging flights both years. When the youngsters are ready to go, they go.

After leaving their nest, young hummingbirds require several more weeks under their mother's watchful eye as they learn to hover at flowers for the nectar within. She continues to feed them out of the nest for a few more weeks, then they're on their own.

Thanks to Don Severson's skills as a photographer, and willingness to drive long distances, we have a bird's-eye view of the nesting process, as if we'd found the nest ourselves.

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.