WATERTOWN, N.Y. (WWTI) — Millions of birds have been flying over the North Country in recent days.

The Cornell Lab of Ornithology is currently tracking a massive bird migration that occurred over the weekend in New York. Scientists originally predicted that over 200 million birds would cross over the Eastern and Central United States each night from April 22 through April 24.

According to the BirdCast migration dashboard, overnight on Sunday, April 24, 2,629,400 birds crossed over Jefferson County. Lewis County saw 3,471,600 birds and 4,424,100 crossed over St. Lawrence County.

BirdCast said that all of these rates are high densities of birds and similar migration rates are expected to continue over the next few days. Migration rates began to spike in early April as spring weather began and continued to increase over the past few weeks.

The organization is predicting an additional 159 million birds will migrate over the Eastern and Central portions of the country tonight on April 25.

As scientists claim this to be a “critical migration period,” North Country residents are urged to turn off or dim non-essential lights. This reduces hazards from attraction to and disorientation by light and allows birds to safely continue their migration.

These birds were measured by BirdCast using weather surveillance radar to track the density of the mass of birds. This measure is turned into an estimate of numbers.