In the last column, I provided some tips on how to predict when migrating birds are likely to be seen in your local patch. Experiencing a fall-out of migrants is exhilarating. In today’s column, we will explore ways that you can experience migrating birds while they are in flight.

Some birds migrate during the day.  We have all thrilled to skeins of Canada Geese or Double-crested Cormorants, winging their way in V-formation to more favorable areas.  Hawks, eagles and falcons are diurnal migrants as well.  They are adept at taking advantage of the vertical winds, called thermals, that form during the day due to uneven heating of the earth’s surface. A rocky outcrop will warm more rapidly than an adjacent forest. The rocks warm the air, the air rises and is replaced by cooler air from the adjacent forest.  That cool air warms, rises and you get the picture.  Hawks are masters at soaring from thermal to thermal, scarcely beating a wing.

A sunny day with winds in the right direction produces spectacular numbers of these soaring migrants.  Mt. Agamenticus in the Ogunquit area and Cadillac Mountain in Acadia National Park have several thousand raptors migrating over them each fall.  Bradbury Mountain in Pownal can be great for spring hawk migrants.

Hawk watching is a boom-or-bust activity.  Make sure the weather conditions are right and you may be rewarded with more hawks than you can follow.

Shorebirds and most of our songbirds are nocturnal migrants.  Advantages of night-time migration are three-fold. The risk of predation from raptors is low. The air is cooler; migrating birds raise their metabolic rate so high they must constantly dump heat or they will overheat. The cooler air helps them balance their heat budget. Finally, the air is less turbulent at night, making powered flight more efficient.

Migrating songbirds mostly migrate at altitudes of 2,000 to 4,000 feet. Shorebirds may fly a bit higher.

How can you see these birds at night? Get your binoculars or, better yet, a spotting scope and train it on the surface of the moon. If migration is occurring, you will see the silhouettes of birds passing in front of the moon’s image.  Don’t expect to see birds flying at their normal migrating height but as birds take off or descend, they are easily seen against the moon.  The technique works well for birds that are no more than several hundred feet above the surface of the earth.

You can also appreciate migrating birds at night from radar images. In the early days of modern radar in the early 1940s, mysterious blips were detected on radar screens. They proved to be no threat to military aircraft.  These echoes were called angels.  Now we know that the angels are small flocks of birds.

The Doppler radar used now for weather forecasting is perfect for detecting bird migration.  Here is the URL for a great tutorial on how to use the freely available NEXRAD radar images to monitor migration:

Yet one more way to appreciate nocturnal migration is to use your ears.  Nocturnal migrants are noisy, regularly emitting short flight notes.  In some cases, the flight notes are similar to the calls the birds give while they are on the ground.  In many cases, however, the flight notes are only given during a nocturnal flight.

Bill Evans has been a pioneer in the study of nocturnal flight calls.  Visit his website at He has sonograms for a number of warblers and sparrows.

On a night that is not too windy, you can hear the flight notes above.  However, a microphone will capture many more of those vocalizations.  Evans provides directions on how to build a microphone system using cheap materials like a plastic flowerpot, saran wrap, a dinner plate and an inexpensive microphone.