Suffering onslaught by black flies or gnats, Minnesota's loons have been abandoning their nests, causing their population in the area to decline over the past few years.

The Department of Natural Resources' Lori Naumann said that black flies in the area were making it difficult for loons to keep their eggs under constant temperature in order to get those eggs incubated properly.

Speaking about the issue, Naumann said, "They have to rotate the egg and they have to sit on it and keep it at a constant temperature in order for those eggs to be incubated properly. And that just doesn't happen when they have to constantly leave the nest to get rid of the flies."

She added that the problem with biting black flies affecting the population of nesting loons had been escalating for the past many years.

Simulium annulus, a species of black flies, has a special attraction to the loons. A research by Michael W. Meyer, published in 2012, revealed that Simulium annulus was chemically attracted to the loons.

Mike McLean from the Mosquito Control District said abundance of water in Minnesota had helped black flies flourish better this year. Black flies or gnats lay their eggs in moving water of rivers and stream. This spring's heavy rainfalls brought more water, which means more eggs hatch.

Authorities have ordered rivers and streams to be treated with natural bacteria to kill black fly larva, which brought a great bringing relief to city residents, but that did little to help the loons get rid of the flies.