Trigger(s) for buildup

[JackM]

Spring buildup...  
Is the only thing that actually triggers the buildup is the beginning of the nectar, which we stimulate by feeding syrup?

Or, will just the presence of new pollen and the fact the hive has plenty of honey begin the buildup?

I ask because my hive has plenty of honey, the bees are getting oodles of pollen, but if I feed, they start to backfill the brood area, which I do not want to have happen....At least I don't think I want that.

Once I saw that a couple weeks ago on my initial inspection, I quit feeding.  Will the pollen they are bringing in be enough stimulus for the build?  (That is being put around the edges of the brood area.)

[Bush_84]

I believe it's multifactorial.  I don't really know what causes a hive to build up, but I suspect it's a combination of increased sun/temperature, pollen coming in, and nectar coming in.  If your bees are bringing in pollen then they are likely gearing up.

[Michael Bush]

Length of days and pollen are bigger triggers.  Enough stores to burn raising brood is helpful as well.

[Kathyp]

I ask because my hive has plenty of honey, the bees are getting oodles of pollen, but if I feed, they start to backfill the brood area, which I do not want to have happen....At least I don't think I want that.

you don't want that.  we are at the beginning of our build up.  you want the queen to have lots of room.  this early, we have more pollen than nectar, although you are lower and may have more trees starting to bloom.  if mine have plenty of honey, i don't feed.  let them bring in the pollen, which they need for brood, and leave space for brood.  just keep an eye on them because they can go through stores quickly when they raise brood and you know how quirky our weather can be at this time of the year.

[Finski]

.
The fact is that sugar feeding does not stimulate spring build up.

Spring build up is a long process, about 6 weeks. How can you feed hives so long?
Yes, you can and you will fill the brood space with syrup.