Barking up the right tree?

 

Can you see the material in this titmouse's bill?

On 7 March 2015, we noticed this Oak Titmouse (Baeolophus inornatus) gathering nest material.  We weren't sure what the material was at first, but eventually figured out that she had a bill full of thin strips of bark.

I checked the Birds of North America account and learned a few things about nesting titmice (in Central California):

- They begin inspecting territories from late February-March

- They build nests primarily between mid-March and April

- The female builds the nest, and takes ~4-10 days to complete it

The base of the nest can be made of a variety of materials.  I was curious about how often bark was used.  (I felt the bark on this shrub and was surprised at just how soft it was.)

Of a survey of 188 nests, here's a basic rundown of what percentage of nests contained these different materials:

- grass (65%)

- hair (35%)

- moss (27%)

- feathers (26%)

- shredded bark (13%)

- sheep wool (11%)

- straw (6%)

- twigs (4%)

- plant down/fibers (2%)

- rope/string (2%)

- oak blossoms (1%)

- snakeskin (1%)

- sycamore seed balls (0.5%)

- rootlets (0.5%)

- leaves (0.5%)

- wood chips (0.5%)

The summary didn't say where the nests were from, and if the materials varied by site.  Are some materials more common in certain areas, or do these percentages stay the same wherever titmice are found nesting?

Have you seen titmice gathering nest material near you?

P.S.  Facts above from the Birds of North America account by Carla Cicero (2000).