The term 'Spring Harbinger' refers to signs of the coming of spring. The crossword solutions for this term are IRIS (4 letters), ROBIN (5 letters), GROUNDHOG (9 letters), THAW (4 letters), CROCUS (6 letters), and REDROBIN (8 letters). The IRIS is a flower that blooms in the spring, the ROBIN is a bird that returns to many areas in the spring, the groundhog is a mammal that is said to predict the weather in the spring, thawing is a process that occurs when temperatures rise in the spring, the CROCUS is another flower that blooms in the spring, and the red ROBIN is a type of ROBIN that has a reddish-brown color. All of these things are associated with the coming of spring and can be seen as harbingers of the season.