This is learned feline behaviour. I suspect that these cats have trained themselves to knock on the front door through observation of their human guardian. It is highly unusual and fascinating to see these cats stretch over from a railing and knock twice as if they are little humans.
The cat in the video above has been described as Britain’s politest cat. The video was made by Sheekilah Jones at 6am in Cardiff, Wales, UK.
She could not believe her eyes. The cat patiently waited for the door to be opened. We are not sure whether someone came to the door. It seems not actually. If no one responded it would demotivate the cat to do this. The reward would not be there. All training is based on reward even self-training.
Here is another version of the top video in case it does not play: