Just remember, before people decided to "help", the bees were doing just fine for millions of years.
For those critters that are truly wild, I believe in letting nature do its own thing.
Where man has intervened, and screwed things up, I feel obliged to do my bit to help.
Once upon a time purple Martin's nested naturally in old woodpecker cavities. Today, the Eastern variety are totally dependent on man made condominiums. The condos become infested with bird mites and bird fleas that MUST be cleaned out and killed each year. Much harder to do is disposing of the invasive species like sparrows and starlings that compete for nest cavities and often drag the baby swallows out to kill them. I love all the wild birds that frequent my farm and forest. It's a cacaphoney of bird song here in the spring. Especially the Martin's, Cardinals, Orioles, Robins, Yellow Warblers, Wood Thrush, Doves, Song Sparrows, and Tree Swallows. But the most amazing is the tiny little Carolina Wrens. They could be nesting anywhere, but their beautiful song fills the air for a mile around.