Well, both really.
Around here I generally start to see butterflies and hummers around the same time. Until then, not much is blooming for either of them. It's normally too cold and only some spring bulbs and early perennials are growing. Then the trees bloom, and spring flowers start to pop.
And I might add, it's generally much later that I see my first hummingbirds than when it shows on the migration map.
I can see where my post was confusing.
Karen