RIVER TALK

Bald eagle construction code

By SCOTT RANDO
Posted 5/17/22

If you happen to see a bald eagle nest while paddling the river or from across the lake, you will probably first notice the size. They are massive nests constructed of sticks.

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RIVER TALK

Bald eagle construction code

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If you happen to see a bald eagle nest while paddling the river or from across the lake, you will probably first notice the size. They are massive nests constructed of sticks. They average over six feet in diameter and weigh several hundred pounds. It is the largest bird nest constructed that can be found in the region. The largest bald eagle nest ever recorded was documented in St. Petersburg, FL as 9.5 feet wide and estimated to be two tons in weight.

Eagles construct their nests fairly high in this area, 80 to 100 feet off the ground. The tree of choice, for about 80 percent of the nests in the region, is the white pine. Eagles pick a tree higher than the surrounding trees (a supercanopy tree). The ideal tree will have a crotch up at the desired height. Ideally, there will be an inverted tripod of branches of sufficient thickness to support the weight of the nest.

Eagles build the bulk of a new nest several months before breeding season, which is when they actually need to use it. The building could be done by a new pair of breeding eagles, or by an established pair building after a nest failure or after a tree or nest has collapsed. Structural failures can occur during periods of high winds; eagle nests are significant wind loads, and they are high up in the tree. This can provide extra leverage to uproot or snap the trunk of a nest tree.

Another cause of nest trees failing is that bald eagles frequently build nests in dead trees. Dead trees may work for a few years, but they are on borrowed time; they will fail early as the wood or roots decompose.

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