<p>Diving Forester's tern protecting territory or young.  Dives are accompanied with "kerr's" and "zarr's" to ward off potential predators of young or eggs.  
</p><p><br></p>
K. Theule / USFWS
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/51986662@N05">USFWS Mountain-Prairie</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/usfwsmtnprairie/20063997693/">Forster's Tern Up</a>