Virgin Planet by Poul Anderson

He could see from above that this planet was inhabited, He emerged from the ship to find himself lassoed and captured by a beautiful redhead mounted on a strange, bird-like creature. That was the first shock; the second was to realise that this world of women looked on him as a monster. For while the women of Atlantis had waited for the coming of the Men, they were certain that this creature who had landed on their planet could not possibly be a man.