Bird watching is perhaps one of mankind’s oldest pastimes. After all, you don’t need anything special to observe and take notes on birds in your area. With millions of migratory birds returning north from their winter vacations, however, amateur ornithologists are taking full advantage of modern technology – they’re using everything from radar to social media to keep up with the migrating flocks.

One of the “birders'” most useful tool is an app called eBird, created by the Cornell Lab of Ornithology and the National Audubon Society. It’s a realtime checklist and database that allows them to pin and annotate their sightings around the world. When a birder notes a sighting, it gets placed on a virtual map with other information. Other bird watchers can then use the map to identify “hotspots” around the globe.

If you think birding isn’t serious business, don’t forget about Hollywood film “The Big Year,” which starred Jack Black as semi-pro bird watcher Greg Miller. In 1998, he was on a quest to identify 700 different species of birds in a single year.

“In 1998, I just had binoculars and a notepad,” Miller told Discovery News. “Now I have a GPS, cellphone and a laptop. These tools have dramatically changed the efficiency of birders.”

These days, Miller also employs Facebook, twitter and eBird to keep track of his sightings. Social media is useful for “crowd sourcing” – Miller cn post photos of unusual birds or birds with atypical markings for their species, and friends and followers can chime in with any info they may have.

Known as the “biggest week in American birding,” this week even has its own twitter hashtag: #biggestweek. Birders are gathering for 10 days in northwest Ohio, a key flyway for migratory species.

Looking at today’s birding technology, those little green Audubon society books almost seem archaic.