Northern Pintail's (Anas acuta) nest.
U.S. Fish and Wildlife Service
1972-06-17
<a rel="nofollow" class="external free" href="https://digitalmedia.fws.gov/cdm4/item_viewer.php?CISOROOT=/natdiglib&amp;CISOPTR=3315&amp;CISOBOX=1&amp;REC=4">http://digitalmedia.fws.gov/cdm4/item_viewer.php?CISOROOT=/natdiglib&amp;CISOPTR=3315&amp;CISOBOX=1&amp;REC=4</a>