don't give up, that's B.S. your sheriff's dept won't do anything. if local law enforcement won't help, i'd call the state police.
or i'd sneak over at night and steal them back. and i'd be armed. its legal to carry an unconcealed weapon, so that's just what i'd do. no way can she steal your pets.
i'm really mad just reading this, so i can only imagine how you must feel.
and i would keep detailed notes of all the conversations with dates and times including those with the sheriff in case you do end up needing to sue.
also, the person who suggested ASPCA is on to something. llamas are good livestock guards b/c they will stomp smaller animals to death so if they are in with a llama and a donkey who both have the potential to harm the birds, they might help you get them back.
good luck to you.