Tuesday, July 27, 2010

Giant Bald Eagle Nest

Last week the High School Naturalists in Training joined me and a couple of teachers for an educational, and fun, float on the Stillwater River. In addition to testing water quality, collecting macroinvertebrates, and having a close run-in with a rattlesnake (aka "buzz worm"), we were lucky to see a most amazing site. On the west bank of the Stillwater is a very large and old nest of a bald eagle pair (Haliaeetus leucocephalus). According to Bird Feats of Montana by Deborah Richie Oberbillig (Farcountry Press, 2008), the largest bird nest in North America belongs to a bald eagle, and was 20 feet tall and 9.5 feet across. The one we saw was not quite as big, but was still very impressive. The same eagle pair has been occupying this nest for at least five years. They return year after year to the same spot and continue to add more sticks each year. After they die, another pair will take over the nest.

Bald eagles eat fish, and that is why they place their nests along rivers, usually in tall cottonwood trees. We were unable to see inside the nest, but had we glimpsed in we would likely have seen a soft bed of feathers, moss, and grasses. Usually the eagles will have 1 - 3 chicks per clutch. Eggs are laid in March or April and are incubated for 5 weeks by both the male and female bird. First flight will occur after 10 - 12 weeks. The young will remain around the nest for several weeks after fledging. We were not lucky enough to see the adults or chicks, however a group in the morning had seen them so we know they are still around!

If you are floating the Stillwater this summer, keep your eyes on the west bank high in the cottonwoods, and you are sure not to miss this amazing spectacle!