It is all based on heat for plants and predators. I don't know about the bird migrations though.
We are going to prune the apple trees after we see them but out. This way we don't cut off any potential apple blossoms. Otherwise, just prune them before they start growing agian. Dormancy is affected by the heat. Look at the growing degree days, if you know what those are. If you don't, look into them, as they come in handy. Degree days relate to insect populations and development as well. That is all the information I can provide though off hand.

Orioles show up in my yard when the apple trees start blooming.

tj

I don't see a set back at all. Although this winter seemed incredibly long, my garden journal from last year shows 6" of snow in the middle of April. (Covered my blooming daffs and tulips). I've seen robins this year, the geese are flying high back north, and my bulbs are all showing.

In my area my journal shows I had direct seeded many cool season crops at this time last year. So I would say I am potentially set back except that germination was very slow when I tried it this time last year (a month in some cases) so I am starting a lot inside to set out in a couple weeks instead of direct sowing.

Last year was just a strange year. We had near 80 degrees in late March followed by teens around mid-April. Right now there's another winter storm watch out for Thursday. Maybe another 6 inches of snow. Spring bulbs and cool season crops are certainly behind, but there's time yet for warm season stuff to be on time...hopefully.

tj

I look at it as the glass half-full. The SE MN/SW WI area has been dry the past couple of years so the snow will help.