Usage of by - required or not

[damodaran]

I read in a novel a line "My dog does not keep the neighbors awake barking at night"

Here, my question is that why is "by" not used before barking? ie "by barking" at night?

Can anyone clear my doubt with explanation.

Thanks in advance.

[Rover_KE]

The character in the novel was speaking colloquially.

Rover

[damodaran]

thanks :)