Most people reading this will probably agree that loons are special. However, when it comes to black flies, you may not realize just how special loons are. The Common Loon is decidedly uncommon because it purportedly shares the distinction of having the most host-specific blood-sucking parasite known to science.
Simulium annulus is the black fly in question. It’s been found that these flies use both visual and chemical cues to find their host and, other than a few confused, myopic individuals with nasal congestion, they are only found on loons and whooping cranes. Since we don’t have cranes in New Hampshire, loons are the only acceptable host for these flies.
The life history of a black fly is ruled by precipitation and temperature. Plenty of fast moving water followed by an increase in temperature is a black fly’s paradise. Sorta sounds like last week’s weather, doesn’t it? Under “perfect storm” conditions, these flies can wreak havoc. In 2014, 70% of loon nests in Wisconsin were abandoned due to a black fly infestation. It all depends on timing and intensity. Climatic trends and projections suggest that the probability of these infestations will be increasing.
But for now, we can only wait and watch. The loons continue to occasionally get on the nest and turn the egg but they can’t tolerate the black flies enough to continuously incubate it.