Sorry, couldn't resist the tern pun...
If you've been to a beach on the Cape lately you have probably seen and heard terns. Lots of them. Terns are colonial nesters and gather in large groups to court, mate, nest and raise their young. They like sandy spots with some grass to afford good hiding spots and also like spots that tend to be a bit more isolated and surrounded by water.
Terns are easy to tell from gulls if you pay attention to just a few things. The terns we get here tend to be smaller than gulls but mostly they look slimmer, more aerodynamic and have long pointy wings. They can hover and dive as well, something you won't see a gull doing.
Because terns tend to hang out by the water's edge many people confuse them with sandpipers. Unlike sandpipers, however, terns do not run along the shore. They tend to be either resting, grooming or getting ready to lift off.
You can learn a lot more about terns by following this link to the Cornell Bird Website.