See more of the story

Songbird migration for the most part is hidden in dark skies.

The birds are up there, leaving daytime roosts about half an hour after sunset, coming to ground as daylight approaches. Millions of birds are moving south to north.

Migrants fly within a large range of elevations, 100 to 10,000 feet, depending on weather conditions and terrain.

If you have normal hearing, and the flight conditions are right, there are nights when you can hear the contact notes the birds continually use to help keep the flock together.

This information and much more is available to everyone on the BirdCast website. You can subscribe for updates on migration. Go to birdcast.info.

BirdCast provides live and local bird migration alerts throughout the country with real-time analysis of bird migration traffic as detected by the U.S. network of weather surveillance radars.

This tool can be used to determine whether birds are migrating in your area on a given night in low, medium or high densities. Heavy nighttime migration could mean excellent birding the following morning when the birds come down to rest and eat.

You will find information at dashboard.birdcast.info. This includes estimates of the total number of birds migrating as well as their directions, speeds and altitudes. Data are available for areas as small as counties.

Birdcast.info also provides migration forecast maps, color-coded to show intensity of movement throughout the country.

Also available is a preview, "Nocturnal Migrants," a list of the nocturnally migrating species most likely to arrive or depart based on frequency of observations powered by eBird.

The BirdCast Migration Dashboard data feed is live from March 1 to June 15 and Aug. 1 to Nov. 15. The live data feed begins each night at sunset and ends each morning at sunrise during migration season.