The Woods Are Full of Cuckoos is a 1937 Merrie Melodies cartoon directed by Frank Tashlin.
Walter Winchell had a well-publicized feud with Bernie at the time, which, like Jack Benny's "feud" with Fred Allen, was faked for publicity purposes – Bernie and Winchell were actually good friends.
Then the song is sung by "Eddie Gander" (Eddie Cantor), "Sophie Turkey" (Sophie Tucker), "W.C. Fieldmouse" (W. C. Fields), "Dick Fowl" (Dick Powell), "Fats Swallow" (Fats Waller), "Deanna Terrapin" (Deanna Durbin), "Irvin S. Frog" (Irvin S. Cobb), "Fred McFurry" (Fred MacMurray), "Bing Crowsby" (Bing Crosby), "Al Goatson" (Al Jolson), "Ruby Squealer" (Ruby Keeler, Jolson's wife at the time), and "Lanny Hoss" (Lanny Ross).
), Joe Penguin (Joe Penner), Tizzie Fish ("Tizzie Lish", a character on Al Pearce's radio show), Jack Bunny (Jack Benny), Mary Livingstone, and Andy Devine (a regular on Benny's radio program).
Finally Owl Kott finishes the cartoon by bidding the audience goodnight, and saying "All is well, all is well..."