I'm glad to hear that crocus is a good plant for honey bees, but Feb/March/April they are also ready to jump on a number of trees for pollen sources. maybe not so noticable as they are often tall trees. Red maple is a good example. Lots of pollen for early rearing of brood, but not so much in the way of nectar. Have to check hives in early spring on warm days to be sure that the bees have enough honey left to make it to spring, as once the pollen starts coming in, the queen cranks up to lay eggs.