Wednesday, March 25, 2015

Bird Nests

Birds are amazing and versatile creatures.  One versatile thing about birds is the differences in the nesting requirements of the various species. 

Bald Eagle at a nest in Kodiak, Alaska (photo: Gay Schroer)
Birds build all kinds of nests.  For example, Bald Eagles build the largest nests of any bird of prey in the world.  Constructed primarily of large sticks and branches, these nests may be used and added on to for many years.  The largest one ever found was about ten feet across, twenty feet deep, and weighed almost three tons!  The nest can become so heavy that it may eventually topple the tree in which is it built.

Conversely, the smallest bird nest is built by the Cuban Bee Hummingbird.  On average they are less than one inch wide and less than 2 inches deep...quite the difference. 

In my opinion one of the most interesting and unusual nests is built by the Sociable Weavers.  The entire bird colony builds the nest, and it can house up to one hundred birds.  Not only are these nesting colonies very large, but some have been observed to be occupied for over one hundred years!
This colony of swallows have built their nests under a highway overpass (photo: Gay Schroer)
However, not all birds build nests in trees.  Many birds, like Gyrfalcons for example, build their nests on the sides of cliffs and have eggs that are less round so they won't easily roll off the cliff.  Snowy Owls, along with many other birds, will make a “nest” on the ground by digging a small scrape in the ground.

This Great Horned Owl commandeered a nest built by hawks the prior year (photo: Gay Schroer)
Not all birds build their own nests either.  Great-Horned Owls will use the nests of Red-tailed Hawks, and Burrowing Owls will use the burrows of small mammals.  Unfortunately, a large number of bird nests are destroyed each year by humans. 

One way to help out birds during nesting season is by building or buying a nest box--a small wooden box designed to fit the requirements of certain species of birds.  You can stop by World Bird Sanctuary to buy a nest box for your feathered friends, or if you're more into Do It Yourself, WBS has pamphlets that show you how to properly build a nest box yourself.

Submitted by Mike Cerutti, World Bird Sanctuary Naturalist/Trainer

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