After initial training as a gravestone carver, Manca studied on scholarship at the Accademia di Belle Arti in Rome and took several prizes there in 1926 and 1927. He came to the United States in 1930 but stayed only two years before returning to his native country.
In 1932, he won a national sculpture competition sponsored by the Legione Carabinieri Reali in Cagliari, Italy. For that project he created four monumental statues and seven huge medallions. He executed a number of portrait busts of the Italian royal family and one of Mussolini who was impressed with Manca's work and helped fund his permanent move to America in 1938.
During his early years in this country, Manca made his living by designing silver jewelery until he had the good fortune of acquiring the former studio of Herbert Adams on West 11 Street in New York. There, he was again able to practice sculpture and his specialities became medallion reliefs and sculptures of animals. In the latter category, his Tiger at Bay was bought by the Fairmount Park Association in Philadelphia; Gazelle and Cactus is in Brookgreen Gardens, South Carolina; and the huge Diving Eagle adorns the East Coast Memorial in Battery Park, New York City. Manca also executed some reliefs for the post office in Lyons, Georgia, and designed the Louise Du Pont Crowninsheild Award for the National Trust for Historic Preservation, Washington, D.C.
He exhibited a number of his works at the National Academy during the 1950s and 1960s. His Lady Gazelle (cat. no. 43) took the Ellen Speyer Prize in 1964 and a smaller version of Diving Eagle (cat. no. S-40) won the Mahonri Young Memorial Prize in 1966.
