webbed feet
... that some water birds use their webbed feet as an aid in elaborate courtship displays?
... that some water birds use their <b id="mwAnY"><a href="./Webbed_foot" id="mwAnc" rel="mw:WikiLink" title="Webbed foot">webbed feet</a></b> <i id="mwAng">(illustration shown)</i> as an aid in elaborate courtship displays?