I sense spring approaching; I see it in the changing quality of the light from "winter" light to "spring" light - with winter light being more transparent, paler, slightly watery. So, too, do summer and autumn have their own quality of illumination. My daughter (14) also notices these changes in the light and commented to me on a recent warm day that although it felt springlike, the quality of the light was still wintry.
I am also seeing signs of spring around the bird feeders: The goldfinches are slowly brightening. The downy woodpeckers are becoming more territorial and less companionable with each other. The blue jays are becoming more companionable and less aggressive with each other. (I delight in watching the jays' feeding rituals, as one selects a seed from the feeder, flies to the wistaria where the other awaits, and gently places the seed in the other's bill.) The male mourning doves are beginning to develop that soft rosy blush on their breasts. The house sparrows have been breaking twigs off the wistaria for some weeks, but perhaps they do that year 'round. I saw two red-tailed hawks circling together last week... And of course the squirrels are going nuts.