Have you ever spoken to the man in the couple? You said it is basically his bird and he loves the bird or vise versa, but if he's allowing the bird to be covered for days on end with a bright light shining on the bird at the same time (I don't at all understand what they are trying to accomplish by blinding the bird while it's covered unless the light is for heat as is the cover, and there's a reason they have that window open, though I doubt it), ignoring the bird and not getting it out of it's cage, freezing it, and allowing his wife to scream and beat the bird's cage with a stick, then he doesn't care about the bird either. But it's possible that he may respond to you talking to him and listing EVERYTHING you've seen and heard. That's how you have to do it, make a point of how birds get stressed easily anyway, and his bird is locked in a cage and never allowed out, even worse he's been covered for day after day, the light, the window and the temperature, the screaming, the beating...Ask him if he'd like to just surrender the bird, and if he says no then you need to ask him why not, the poor bird hasn't even been uncovered for days let alone interacted with. This conversation should either have him giving the bird up, or improving upon the bird's condition. But it seems they don't like the noise from the bird and that's why she yells and hits the cage, which obviously will only make the problem worse. I don't think the police will do much, but they can tell you who to call in your area, such as animal control, a rescue, etc.
Either you need to confront the man and give him a choice, or you need to contact the proper authority in your area. Either way you cannot leave that bird to live out it's life in that home that way. Those are your options, you must do something. But as already stated you may have to temporarily take the bird upon speaking to him, which is exactly how I would approach it. I would tell him that I am prepared to take his bird right now and get it to a rescue where the bird will be treated with love, affection, will be interacted with, and will not be abused. Then take the bird if he offers and get it out of there. Then you can find a rescue. First is to get the poor bird out of there if possible. If he won't give the bird up then you have to call the proper animal authorities.
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