conuly

Well, of course there are many first signs of spring - when snow melts and stays away for a week while, when you come home from work before it gets dark, when temperatures climb above 5°C...
Additionally, spring kind of comes in stages here - pre-spring, Easter spring and post-spring, so to say, so what we call spring would probably still qualify as winter in other places.

But the thing that makes most people go all "Yay! spring is upon us!" here is the common snowdrop (even though that is technically a winter plant). Once the snowdrops flower, you know it's only a week or two to crocuses and willows and a month to forsythia and narcissas and easter eggs. And after that? Well after that, there's too many flowers and birds and stuff to count. ;)
(Robins definitely wouldn't be the first bird of spring in these parts, as robins stay here for the winter so you see them all the time.)