Tom's Blog

Sunday, September 14, 2014

Baltimore oriole nest

We've been having Baltimore orioles nesting near our cabin for quite a few years. They build their characteristic nest in a nearby decrepit elm. We ought to fell this tree but won't as long as the orioles  use it.

Several days ago during a stiff wind the oriole nest, now no longer used, came down and Kathie found it. The structure is impressively complex, as the photo shows.

How do they make it?

According to the Cornell bird web site, the female weaves the nest from various types of fibers: grass, strips of grapevine bark, and wool, as well as artificial fibers such as twine or fishing line. They may also use fibers from an old nest to build a new one. Males may occasionally bring nesting material but don't help with the weaving.

The nest is built in three stages:

  1. Construction of an outer bowl of flexible fibers for support
  2. Springy fibers are woven into an inner bowl, which maintains the bag shape
  3. Addition of downy fibers and feathers to provide a soft lining which cushions the eggs and young.
They do one brood a year and the clutch size is 3-7 eggs.

At lunch we spent some time looking at the structure. Under a hand lens the fibers of this nest looked mostly like bits of cloth, although it was also possible to see strands of plant material. According to Cornell, no knots are tied, but some do arise due to random poking of fibers.

It's hard to imagine how someone without hands can make such a structure!


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