Good job rescuing your new goose! They make wonderful pets! I sure wish I hadn't waited 35 years to get my first one (who knew
they'd be so personable) !!! My geese shake their heads and a liquid will come out too. I believe it's pretty normal. My gander, especially, will shake his head almost every time he approaches me. Sometimes, if I forget and kneel down to greet him, I get a fairly descent spritz right in my face. He also has this strange habit of, well...how do I say it...burping...as he's greeting me. He'll see me, shake his head, spritz a little liquid, 'burp' and then shake his head again and then he'll start chewing! It's very bizarre, I know, but I honestly think he's regurgitating his food for me. Like he's trying to give me a tasty sample of his previous meal! I've had various breeds of birds before, but the only other one that ever tried to feed me was my parrot Bosley. Anyway, I wish you luck and much happiness with your new goose and 'kudos' to you for saving its life!