<p>Whilst I was observing them trying to build the nest, they were severely harrassed by a female Nuttall's Woodpecker.  I have been back to this potential nesting hole many times in the last 4 weeks but the titmice obviously chose to nest elsewhere.
</p>
Best seen in black.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/32541690@N02">Alan Vernon</a>
CC BY 2.0
<a href="//commons.wikimedia.org/wiki/Flickr" class="mw-redirect" title="Flickr">Flickr</a>: <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/32541690@N02/5728919860">Oak Titmouse bringing a treat to its partner in the nesting hole.</a>