Rare Bird: Mountain Bluebird

I have had a Mountain Bluebird pair build a nest in my nest boxes for the past 3 years. In 2014 I started feeding the Bluebirds mealworms in a tuna can nailed to the top of a fence post in my yard. It must be the same pair, or at least one of the ones from the previous year because as soon as I put the worms in the can the bird flew from a shed roof to the can. They come every morning for the worms. I only feed them once a day, but they visit periodically through the day to see if there is anything in the can. This is the earliest they have come, though. They arrived on March 20.