What bird signals spring?

People have been telling me about American Robin sightings all week.  Robins are not a reliable sign of spring.  Many robins stay in Mid-Michigan all winter.  I have regularly seen flocks ranging from 10 birds to more than 50.  They are just easier to see now.  During the coldest weather they were keeping to wooded areas where they fed on berries and other fruit.  Now, with no snow cover and most of the ground thawed, they are beginning to appear in lawns and other grassy areas to search for worms and other invertebrates.

If Robins are not a true sign of spring what bird is?

Red-winged Blackbird (Agelaius phoeniceus) - photo from March 2016

To me it's the Red-winged Blackbird (Agelaius phoeniceus).  While driving home yesterday (23 February) we saw three of them along US-127.  This is ten days earlier than my first sighting last year.  All of the Blackbirds that we saw males.  They are busy trying to impress each other and jockeying for territory.  It may take a couple of weeks to sort out which bird ends up with the best places in the landscape.  In the meantime, the females should find their way north to Mid-Michigan.

Females will then set about choosing their own territories (within those of a male).  A dominant male bird may have several females living in his territory and will mate with each of them.  The females select a mate based on territory - a male with a good territory will more likely have good genes to pass on to his offspring.  So it doesn't bother them that their mate may have other mates. The females are also likely to mate with more than one male.