Loons Threatened by Surge in Black Fly Swarms

Loons are being driven from their nests by an explosion in biting black fly populations. The consequence of this? The next generation of the birds may prove dangerously small.

According to loon expert Walter Piper, a researcher at the School of Earth and Environmental Sciences at Chapman University in Orange, Cali., this is the worst year ever seen for blood-sucking black flies - which are especially affecting some of the country's largest loon populations, who bed down to incubate their eggs in Northern Wisconsin.

Piper, who keeps a regular blog detailing his study of loon populations, is rather upset about this "plague" of flies that is so heavily disrupting the loon birthing process. Normally both a male and a female loon will mind their eggs equally for 27 days, taking turns to incubate the eggs for several hours while their partner tends to personal needs. However, while this seems like a remarkably fair parenting strategy, it is actually causing the birds to become more vulnerable to failure.

"We have a case where the weakest link breaks the chain," Piper wrote last week. "Even a tough, determined male incubator is destined to lose a clutch if his mate is less determined than he is and refuses to sit on the eggs and tolerate the torment of biting insects."

For the 2014 breeding season, Piper has estimated that a whopping 70 to 80 percent of all nesting loons have failed to properly incubate their nests this year.

"This is much the highest rate of blackfly-induced abandonment that I have seen in 22 years of loon study. (32 percent was the worst rate before this year)," Piper reported at the end of last Month.

Piper explained to the Associated Press that things are so bad this year because a cold spring in Wisconsin and rapid warm up in May caused the blackfly population to delay and then explode in numbers, hitting the loons hardest right when they are most vulnerable.

Alarmingly, the blackflies appear to be hell-bent on bothering loons almost exclusively.

A study conducted by the Wisconsin Department of Natural Resources and published back in 2012 details how the black fly species Simulium annulus is not just drawn to the loons because, without being able to leave their nest, they are easy prey. The flies are actually chemically drawn to the birds, exhibiting a very targeted parasite-prey relationship.

Thankfully, according to Piper, there is still time to salvage the situation.

"Most pairs that abandoned their nests due to blackflies did so within the first week of incubation. Thus, they still have plenty of time to renest, which most will do soon," he said.