April 25, 2024: Kate Wong explains why now may be the best time to get into birding. Plus, how we can catch a glimpse of the far side of the moon, and bird flu in the U.S. milk supply. —Andrea Gawrylewski, Chief Newsletter Editor | | | Wrentit forages at Point Dume, Calif. Kate Wong | | | Bird-watchers in the Northern Hemisphere are delighting in the spring migration of billions of birds from their southern wintering grounds to their breeding grounds in the north. In my corner of New England, the migrants have been trickling in—Tree Swallows, Ospreys, Greater Yellowlegs, Chipping Sparrows and Hermit Thrushes, among others. In a couple of weeks, we'll hit peak migration, with loads of warblers, vireos, thrushes, flycatchers and sandpipers arriving on southerly winds, all flashing their finest plumage and singing their signature songs. If you've ever had an interest in birds, consider joining the community of people who love to share their knowledge of these incredible animals. There has never been a better time to be (or become) a birder. The appeal: Birding can be as meditative or exhilarating as you want it to be. It's deeply satisfying to encounter a bird in the wild, figure out what species it belongs to and observe its behavior. And the thrill of finding a bird you've especially wanted to see or that is rare will set your heart to racing. I recently set out on a quest to find some wishlist birds in California—and was richly rewarded for my efforts.
How to get started: Get some binoculars and a good guide to bird identification. New tools make it easier than ever to find and identify birds. Check out the eBird online database, where birders track and share their bird sightings; and the Merlin Bird ID app which can help identify the birds you see or hear. Join a local birding group (you'll learn faster if you bird with birders who have more experience than you do). Go look for birds—out the window, in the yard or in a nearby park—birds are everywhere! – Kate Wong, s enior editor, evolution and biology | | | The moon seems to be split into two halves: the hemisphere that always faces Earth, which we call the near side, and the half that always points away, known as the far side. But in fact, we see about 59 percent of the moon's surface, thanks to its gentle nodding north-to-south and leaning east-to-west over the course of a month. This subtle oscillation is called libration. How it works: The moon's orbit is elliptical rather than circular. So when it's closest to Earth in its orbit (perigee), the moon moves a bit faster and its relative spin rate is a bit slower, and opposite when it's farthest from Earth (apogee). At apogee it rotates its western side a little bit more into our view, and at perigee we see a little bit more of its eastern side, totaling about 7.5 degrees of lunar landscape on each side. Plus, the moon's orbit of Earth is tilted by about five degrees (called its inclination), meaning that when the moon is at the northernmost point in its orbit relative to Earth, we can see a little bit more surface past its south pole, and at its southernmost orbital point we can see farther into the far side at the north. Watch a mesmerizing video of these effects made by NASA.
What the experts say: "When I was in high school, I shot a lot of photographs of the moon using my telescope and camera," writes astronomer Phil Plait. "I remember seeing Mare Crisium, a dark impact feature near the moon's eastern limb, clearly closer to the moon's edge in one shot than the other. I had discovered libration!"
| | | • Bird flu is in U.S. cows: Is the milk supply safe? | 4 min read | | | • The first of two broods of cicadas has started to emerge. If your pup happens to chomp on one, don't worry, it's fine. Even you can take a bite! | 6 min read | | | • In the latest episode of Lost Women of Science: Psychologist Elizabeth Bates took on famed linguist Noam Chomsky over his model of how humans acquire language. | 39 min listen | | | • Forests are valuable sinks for global atmospheric carbon dioxide. For example, U.S. eastern temperate forests alone currently remove about 34 megatonnes of CO2 from the atmosphere per year. Although much attention is paid to the value of tropical forests, we must turn our attention—and dollars—to temperate trees, or face the loss of an important tool in managing global warming, write Amanda Leland and Steven Hamburg, executive director and chief scientist, respectively, of the Environmental Defense Fund. | 4 min read | | | OUR MOST POPULAR STORIES OF THE WEEK | | | • After Months of Gibberish, Voyager 1 Is Communicating Well Again | 3 min read | • An Epitaph for Daniel Dennett, Philosopher of Consciousness| 5 min read | • The U.S. Spends a Fortune on Beach Sand That Storms Just Wash Away | 6 min read | | | Like my colleague Kate, I too caught a bit of the birding bug during the early months of the pandemic (though her case appears to have stuck). On long walks in Central Park I learned to look UP into the trees and spotted a surprising array of birds, from Red-Winged Blackbirds to Northern Flickers--commonplace creatures to northeastern forests but thrillers to novice observers. Late one afternoon I spotted the tall body and spiked featherhead of a Belted Kingfisher perched high above the Loch (a stream that runs northwesterly through the northern part of the park). I barely muffled a yelp of joy. | Weekends are a great time for birdwatching. Enjoy yourselves and let me know what you see: newsletters@sciam.com. Until Monday! | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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