06/12/2026
Happy Loon Fact Friday!
Late May and early June are a critical time for Adirondack loons. As nesting gets started, the adult loons start to face several challenges that can affect their chances of raising chicks. One of the biggest threats is the black fly, these are a blood-feeding parasite that targets loons, and as we know people. To avoid swarms of biting flies, incubating adults spend more time in the water and less time resting or preening. In years when black fly numbers are especially high, the effects can be dramatic. Research has shown that up to seventy percent of first nesting attempts may be abandoned. While staying on the nest can lead to successful hatching, prolonged exposure to black flies can also increase the risk of parasite transmission, which can negatively affect a loon’s health and future survival. Black fly transmit parasites through their blood feeding bites, injecting microscopic infectious larvae directly into the host's skin.
If it comes down to it, giving up a nesting attempt may seem damaging to their reproduction cycle, but many pairs can try again a few weeks later after black fly numbers have dropped. This strategy may reduce the chances of producing chicks that year, but it can help adults maintain their health and improve their odds of breeding successfully in the future. Scientists also suspect that age may play a role in these decisions. Older males, with fewer breeding seasons ahead of them, may be more likely to continue incubating despite heavy fly pressure. Younger males, by contrast, may benefit more from abandoning a nest and preserving their condition for future years. Because both members of a pair share incubation duties, however, the decisions of one bird can be influenced by the behavior of its mate, making this a fascinating area of ongoing research.
To learn more go to: adkloon.org
