Which species of lemur can sing?

Ring-tails are completely at home in the treetops, the bare upper branches of the tamarind made an ideal arena for a morning assembly. Here the lemurs would climb to their favourite perches to bask in the first warming rays of sunshine. It was a time to be with friends, to groom, to play or to tend to the needs of infants. One of the males would climb to a perch on one of the highest branches to sing, sending a message far across the forest proclaiming the troop'sownership of this treasured tree

Ring-tails are correct!