A nesting Anna's hummingbird. (Eric Pittman)

The ridiculous extremes of weather of late have unsettled not just the plants and the gardener on the landscape stage, but the songbird.

The balmy late winter (before it turned cherry-blossom frigid) encouraged a white-throated sparrow in my garden to build a nest in the climbing hydrangea. The nest was later abandoned, presumably after the sparrow noticed the freeze damage to the magnolia tree and hydrangea bushes, and decided that spring had jumped the gun.

April, everyone hopes, will hit the spring reset button. We can get on with planting, and the birds with building nests, laying eggs and raising their young. The next eight weeks offer, for many types of birds, their one chance in the year to produce a new generation.

This nesting business is an extraordinary and perilous feat. Parent birds must gather the materials to fashion a nest, build it at just the right spot — sheltered and away from predators — and then incubate the eggs. Once the babies arrive, life is a continual hunt for worms and flying insects to feed the young. Fledglings make the leap in May and June, a particularly fraught time.

Rearing chicks can be trying for the gardener, too. Forget about pruning the hedge where the birds are nesting or oiling the wooden bench in the vicinity — the avian parents get anxious and the best thing we can do is give them some space.

Western tanager. (Timothy Lenahan/Audubon Photography Awards)

But if you want to turn your curiosity into something of scientific value, consider NestWatch, the Cornell Lab of Ornithology’s springtime enlistment of citizen scientists to monitor nesting birds. Volunteers across the United States register to track the progress of nests around their homes. Last year, more than 2,000 registrants tracked 21,000 nests, said Robyn Bailey, the project leader.

The monitoring does involve some contact to check the number of eggs laid and how many nestlings survive, but watchers are instructed in how to minimize the disruption.

This rite dates back to 1964, so the annual data offer valuable insights into such matters as the shifting range of birds. In that time, the records have helped to establish that bluebirds, for example, are now doing well after a period of decline, but that the American kestrel and northern flicker seem to be scarcer.

Some species can be helped with nesting boxes — bluebirds, wrens and chickadees, for example. Others don’t need any help, thank you, and build their nests in generally conspicuous places, such as mourning doves and robins. Other common species, though, are more secretive. Goldfinches, which nest in the summer, generally make their teacup nests in the lower branches of trees, while dark-eyed juncos actually make camouflaged ground nests. Some nests are inaccessible. Binoculars will help figure out the offspring situation. For barn swallows, “it’s easy to find the nest but they tend to be a bit high,” Bailey said. “That might be a selfie stick kind of situation.”

This year’s NestWatch comes with an app that should make recording data more convenient, she said. A focus of this year’s observations, she said, will be in trying to see if bird feeders have a measurable effect on the success of the enterprise.

Whether you monitor a nest or just take it in as part of the spring experience, you should not bother the parent birds, attempt to move a nest to a more convenient spot or generally interfere. “Outdoor cats are definitely a problem,” Bailey said. She puts her cat on a harness when she takes it into the garden.

Purple Martin hatchlings. (Richard Winegar)

Separately, the National Audubon Society is launching an online guide to selecting native plants of particular value to birds, either directly as shelter or food, or indirectly in attracting insect larvae that nestlings need in large quantities to develop.

Configured to offer plant lists for your growing zone, the society’s Plants for Birds database offers a comprehensive range of trees, shrubs, perennials and grasses that provide an array of support for birds, particularly those spring migrants moving north.

I would add that you might also consider your space and site conditions before sticking in, say, an American basswood. This is a handsome linden, and Plants for Birds says it will sustain such beauties as cedar waxwings, grosbeaks and vireos. But it’s a big tree that will define a landscape. You might just have space for some salvias for the hummingbirds.

What I found fun about this database is that I could type in existing plants in the garden to see which birds are drawn to them.

Part of the motivation, said John Rowden, director of community conservation, is to enlarge the suite of plants available to birds because climate change threatens to disrupt the synchronization of arriving birds to food sources. Plants leaf out in response to temperatures, and many birds are spurred by increasing day length, “so there can be mismatches,” he said.

@adrian_higgins on Twitter