The furry light gray flowers of pussy willow burst from their buds.
The first of the migrant red-winged blackbirds are returning north. The earliest groups are made up almost entirely of adult males. Look for them perched on high marsh reeds and rushes such as cattails, displaying their bright red and yellow shoulder patches, or epaulets.
Great blue herons return to rookeries; they begin nest building and repair almost immediately upon arrival.
Vernal equinox: first day of spring. Night and day are of equal length.
Full moon. The Fish Moon (Colonial American).
Mourning cloaks, among the longest lived butterflies, overwinter as adults in tree crevices and beneath loose bark, and emerge on warm days in early spring.
Tree swallows return. Look for them scouting for nest boxes or tree cavities as breeding season begins.