Paducah radar images on clear night turn out to be thousands of migrating birds

A radar image this week at Paducah's National Weather Service office turned out to be tens of thousands of migrating birds.

Early Friday morning, meteorologists noticed the dark green spots on their radar even though there was no precipitation occurring.

Further investigation revealed that right now is one of the biggest weekends of the peak fall season for birds flying south for the winter. Their radar was actually detecting 50,000 to 70,000 birds passing by each hour overnight at altitudes up to 1800 feet.

A check of the website Birdcast showed that 1.5 million birds passed over McCracken County on Friday night.

Bird migration for the fall actually starts in August through November, but the peak in our region is underway. According to the Cornell Lab of Ornithology, 500 million to one billion birds are in the air each night across the eastern half of the nation this week. They'll make their annual return trip north through our region in late April and much of May.

Many species of birds travel 500 or 600 miles in a single night. Along the way, they rest and feed during the day. Spring and fall are busy times for birdwatchers, too, when they can spot species passing through that aren't local residents.

Birds migrate by using a complex combination of sight and smell, celestial cues like the sun and stars, and the earth's magnetic field. They also follow established routes, known as flyways, which often align with major geographical features like coastlines and rivers.

Many birds using the Mississippi River Flyway spend their winters in South and Central America, then travel northward along the Gulf of Mexico before following the Mississippi, Missouri, and Ohio Rivers to the Great Lakes and Canada.

Other triggers, such as the shortening hours of sunlight in a day, influence their internal biological clocks and genetic programming.

A modern problem for birds is the increased use of artificial lighting, especially around cities. Millions of birds are killed when they get confused and run into bright high rise buildings, towers and glass windows. Many locations, such as the St. Louis Arch, turn off extra lighting during migration to help keep birds on track.

There are plenty of informative sites online about bird migration, including Birdcast with daily local data.