For the Birds Radio Program: Blue Moon (reworked from 1990)

Original Air Date: Jan. 29, 1999

Do birds pay attention to the moon?

Duration: 4′18″


Sunday night’s full moon is the second one of the month, making it a blue moon. Blue moons occur a bit more than a coon’s age–a raccoon’s life expectancy in the wild is about five years, and in captivity a good 15 years, while a blue moon comes along every 28 months or so.

Birds don’t keep track of the calendar in the same way that we do, but they do pay attention to full moons. Owls hunt more easily by the light of the silvery moon. Saw-whets and Boreal Owls generally hunt for their mice while perched in conifers so their silhouettes won’t stand out too much–in a full moon they find food more easily but in turn are more vulnerable to Great Horned Owls eating them.

Early spring nights are full of sound, from spring peepers and chorus frogs in thawing puddles to woodcocks dancing past the moon. Woodcocks have fairly specific light requirements for their sky dance–they quit when it gets too dark, but can keep it up all night long in a full moon. Bitterns and rails can be heard throughout the night during a full moon. Whip-poor-wills and nighthawks sometimes call later into the night during a full moon, too. And on May and June nights, songbirds sing in their sleep, or maybe when they can’t get to sleep. This nocturnal singing seems more pronounced during bright moon-lit nights.

But songbirds and other diurnal species aren’t affected much by the moon in wintertime, at least not as far as we know. Actually, for all we know they may prefer sleeping with a nightlight on, or–who knows?–they may all get up at midnight and watch the Rocky Horror Picture Show by moonlight. But as far as ornithologists know, they pretty much ignore the winter moon.

It’s not until migration begins that the moon plays an important tole in the lives of most birds. People once believed that songbirds flew to the moon for the winter, and the reality is almost as unbelievable. Mallards, and possibly other species, actually use the moon’s position in the sky relative to the time of night to help them navigate. A bright full moon makes it difficult for birds to see stars, so species that rely on celestial navigation may prefer traveling during clear, moonless nights, sleeping in when the moon is too bright.

Researchers used to regularly keep telescopes trained on the moon during migration, to watch the movements of flying birds. They can determine which directions the birds fly in and extrapolate the number of migrants by the apparent area of the moon relative to the apparent area of the whole sky. Although few birds can be identified down to species, many large birds can be easily recognized. The method is more useful in the United States and Canada than in Britain and Europe, because over there the full moon during spring and fall is too often obscured by clouds blown in on the prevailing winds from the Atlantic Ocean. Nowadays, though, few researchers use the method, most preferring more sophisticated radar techniques. Bird-watching by the full moon is limited to spring and fall–you could shiver out under a winter moon for a coon’s age before a single bird would appear–though it might happen once in a blue moon.

Sunday’s blue moon will reach its highest point in the sky at 10:08 pm, and by midnight, January will come to an end, along with National Blue Jay Awareness Month. But unlike the Blue Moon, Blue Jays will still be hanging around the Northland in the morning, and will stick out the worst of winter with us. You can’t lasso the moon unless you happen to be Frank Capra’s George Bailey, but if you have enough time and patience, you can get a wild Blue Jay to alight on your finger for peanuts. The fun and beauty that a Blue Jay brings to a winter’s day, even when it’s not National Blue Jay Awareness Month, can warm the human heart far more than the cold moon shining in the winter sky.