New characters were added to Tom and Jerry cartoons by Bill Hanna and Joe Barbera to keep the series fresh. One of them was a canary in “Kitty Foiled” (1947).
The bird unhooks the bottom of its cage so it’ll fall on Tom, allowing Jerry to escape. You can see the weight in the first drawing below as the bird pulls on the latch. In the second drawing, you can see the sense of balance as the bird is thrown backward a bit by the force of the latch loosening.
Then the impact as the cage bottom flattens Tom’s head. Who else in the H-B unit but Irv Spence would draw like this? (See the answer in the comment section).
Ken Muse, Ed Barge and (for a change) Irv Levine receive the other animation credits.