Eagles and Loons

May 31, 2023

Four loons on one small lake should be enough of a disruption for a territorial loon pair. Imagine living in an environment where you are subject to attack, not only from any side, but also from beneath. It’s no wonder that birds and aquatic mammals can practice unihemispheric sleep. Otherwise, it would be near impossible to get any rest.

To add insult to injury, the local bald eagle pair has been regularly visiting the lake, making it necessary for the loons to be constantly aware of what’s going on above as well as beneath them. This clip demonstrates the chaos eagles can inflict on loons. Although an eagle can rarely take an adult loon, it does happen on occasion. Loon chicks are much more susceptible to eagles, as evidenced in this clip.

But loons can fight back. In the summer of 2019 a dead eagle was found floating in a Maine lake. A necropsy showed that it had been stabbed through the heart. Further investigation revealed that the carcass of a newly hatched loon chick was also found nearby. The conclusion was that the eagle got the chick but an adult loon got the eagle, using the same tactics employed for protecting it’s territory from intruding loons.

Eagles have been making a strong comeback in New Hampshire. Considered extirpated in the 1970s, mostly due to the pesticide, DDT, the first confirmed territorial eagle pair returned in 1988. They remained as the only known pair for ten years, but around the year 2000 the population began a rapid increase. The 2022 census counted 92 territorial pairs in New Hampshire. The majority are along the Connecticut River and in the Lakes Region.

LPC has been following New Hampshire Audubon’s eagle population surveys and a study led by LPC Senior Biologist John Cooley showed that loons near an eagle nest experienced a higher rate of nest failures. This could be a cause for concern but, compared to anthropogenic stressors such as lead tackle, boat collisions and habitat degradation, eagles do not appear to cause any significant population effects. Eagles and loons have dealt with each other since time immemorial. They will both continue to prosper as long as we practice good stewardship.