Agreed with Quaeitur for "oiseau moqueur" because on the one hand the exact geographical location of the song writer at the time of writing must be known to specify which of the numerous species of mockingbird (moqueur polyglotte, moqueur des savannes, moqueur de Patagonie, moqueur du Chile...) is concerned and on the other hand simply using the ornithological generality "moqueur" would leave the listener uncertain as to whether it concerned a bird, a human, a monkey or a supercilious ant.