Green’s Dictionary of Slang

catbird adj.

[ety. unknown; predates catbird n. (1)]

(US) perfect, ideal.

[US]J.C. Neal Charcoal Sketches (1865) 138: If you want to feel something like – do you know what ‘something like’ is? – it’s cat-bird, jam-up – if you want to feel so, you just pour a little of the electerizing fluid into you.