<p>The bank swallow has a unique distinguishing characteristic in that it is the only swallow that does not build a nest. Instead it forages holes  reference &lt;a href="<a rel="nofollow" class="external free" href="http://bss.sfsu.edu/holzman/courses/Fall00Projects/Bankswallow.html">http://bss.sfsu.edu/holzman/courses/Fall00Projects/Bankswallow.html</a>" rel="nofollow"&gt;bss.sfsu.edu/holzman/courses/Fall00Projects/Bankswallow.html&lt;/a&gt;
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It is North America's smallest swallow.
<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@N02/3875961099">Bank Swallow (Riparia riparia)</a>