After appearing in our backyard a couple weeks ago, and then disappearing during the huge snow dump of April 7th and 8th, our one robin has returned to remind us that it's spring.
The first robin is usually most noticeable in early morning becuase of the distinctive song it sings after (while? during?) getting the early worm. Typically, after a few days of hearing the song, we will finally see the robin sitting on a high perch in a nearby tree. Shortly thereafter, the first robin's many robin friends will arrive, and we will know that spring is in full swing. We are still awaiting that latter stage.
Other people, I am told, mark the true arrival of spring by the opening of the local golf course. Not I! I'm more of a robin-type of person.