At the opening card sequence that has a copyright notice, it reads "Copyright MCMXLI by The Vitaphone Corp." A results found for the record entry was listed across the initial registration list in 1941 nor the renewal registration list between 1968 (1, 2) and 1969 (1, 2) on the copyright catalogues.
The animated short film entered the public domain in 1970 after Warner Bros.-Seven Arts (a successor of Sunset Productions/Guild Films for pre-1943 black-and-white titles) did not renew the original copyright Vitaphone within the required 28-year period.
The animated short film is widely available in both physical and digital formats.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.