Like a loon's, a tern's feet have this feature, yet terns are not notable swimmers
This is ... And, like submarines, they can dive deep; Common Loons have 
been... [DOC] [TLE] Abstracts - The Waterbird Society [PAR] Overall, this model has helped us not just identify areas frequently .... landscape-
level processes like climate change, threaten the temporal and .... Common Tern 
nesting behavior and colony disturbance on a natural Island in Northern Lake 
Michigan .... Our findings show that loons swim by synchronously paddling their 
feet.