Sparrows showing signs of...

Bulimia nervosa (bulimia).
This is a mental disorder that also affects how you feel about your body and how you eat. But with bulimia, you eat a lot of food in a short period of time. This is called bingeing or binge eating. While you eat, you might feel like you can't control how much you eat.

Sun is in wrong place to see these birds clearly. But you should get the right idea about their love of suet balls. (And the very dense ones too!)
They would easily demolish 8 in one day given half a chance!

Extra blip ~ goldfinch feasting on fallen daisy petals. Taken though glass at a distance, so not very sharp!