Eggs and Predators

Out of all the loon nest attempts LPC has monitored over the past four decades, about 40% of the nests fail. Out of those that we can determine the reason for nest failure, egg predation is the most common cause. On June 4 a snapping turtle visited the nest and had a stare-down with the loon. It was an anxious moment but the snapper finally backed off. It’s highly likely that both the snapper and the loon have had encounters before and, although it’s a given that a snapping turtle would enjoy an egg breakfast, it wouldn’t be worth the risk of being impaled by the loon’s bill.
Snapping turtles are not known to be loon egg predators. Egg loss due to predation is generally caused by either birds or mammals. Of the birds, crows, ravens and gulls are frequent egg predators. Larger birds may be able to carry off the eggs and eat them at their leisure. Otherwise, they will just punch a hole in the egg with their bill and suck out as much of the contents as they can before the loons chase them off.
Any mammal that benefits from animal protein in its diet can be an opportunistic egg predator. And that includes most of the rodents, as well as the carnivores. But of the mammals, the most common loon egg predator is the raccoon. Loon nests are smack dab in the middle of a raccoon’s favorite hunting/scavenging habitat (well, maybe second to dumpsters). Raccoons and other larger mammals will usually try to carry the egg(s) to higher ground behind the nest where they are beyond the range of irate loons. Other common mammalian egg predators include mink, fox and coyote.