Some of the sea birds can do without drinking fresh water, but the shore birds drink and bathe wherever they can find a freshwater pond. The timing of this is based on the tides, just as the tide begins to rise the activity at this little pond increases. If you ever went birding, and didn't see anything, maybe your timing was wrong. You don't have to be near the ocean for the natural clock to work, it's all tied to the sun and moon cycles. There is a link on this page to the SOLAR/LUNAR charts, take a look at it, see if they work for you. I've found them to be a good predictor of wildlife activity, when the critters are napping I can nap too!