Many people hear their howls like the wolves are crying, but no they're communicating. When the brown wolf howls to Balto it's not saying anything to the town it's standing in front of feeling curiosity, it's being kind and asking Balto if he'd like the join the pack. When Aniu howls just a few feet away from Balto she's telling Balto don't give up, and when Balto howls with her he's telling Aniu he won't that he won't give up. When Balto howls happily to Jenna he's telling her he's returned, he's also expressing his pleasure of his success in making it through the hard blizzard.
When Aleu howls on top of Muk and Luk by herself she's expressing her self-respect, but if she was with the wolf pack it would have been a moment of the alpha telling the pack they were welcome to eat some prey. That's how meal time goes with wolves, the alphas usually eat first but if it's a large prey the whole pack is allowed to eat together. Things like deer are considered medium prey but wolves would consider bears and buffalo gigantic foods, but wolves are prudent enough to usually leaves these two huge foes alone.
During the song The Grand Design The wolf pack isn't howling at the moon, no They're expressing their hope as well as their courage. The wolf pack first had no idea what would be a safe way to cross the sea with how strong an ocean's currents and splashing waves can be. It's the words from Balto and Aleu that helped them figure it out. When Aleu joins the wolf pack as their new strong alpha they're howling their trust in her and their confidence, while Aleu howls her acceptance of leadership because she feels like she found where she belongedFor a while Kodiak doesn't have self-confidence of winning the sled against airplane race, so when he's howling with his friends in Nome he's feeling like dad I can't do it without you. It's when Kodiak worries less that he gains courage and becomes the hero he wished to be. Kodiak's howls to his father Balto on the slippery cliffs was him telling Balto me and my friends we're here to save you dad. And the pilot was pleased to not die on the freezing ice and snow on Alaska's wide mountains.