Don't know the site well enough to be able to tell if the chick could have wandered outside the box - if it did, the parent(s) would have hung out with it until it returned the box (with or without parental coercion) or was returned with human help. Or the chick could have been removed by said same humans to make sure it hadn't suffered any ill effects if they were concerned about it being left "alone". I use quotation marks around "alone" because again, without knowing the layout of the site better, I can't say that chick was actually alone. Depending on the weather, there may not have been any need for the adults to keep it warm and they may have just been sitting a cm out of camera range which wouldn't qualify as "alone", just not "sitting on top of". The Maine adults and Sumo are not the norm, our birds don't tend to sit on or beside the chicks by banding age when they are in the nestbox, the chicks are mostly with each other not Mom/Dad.
Does that help?
