This is a scene I saw in a Looney Tunes episode somewhere between 2000 and 2010, although I'm not entirely sure in which animated series it was; I would like to believe it was The Sylvester & Tweety Mysteries, but I am not entirely sure.
Basically, there is a scene like this where you see the Minah Bird walk and hop in a city. A dog is following behind him (you see them from a side view). And when they get to a light pole, the Minah Bird disappears, and the dog wonders is confused because there's obviously nothing about the light pole itself.
I suppose that gag is recycled in the drawing below:
The way I remember it, that scene happened in some kind of city. They were walking on the pavement, the surroundings looked like buildings (I mean, it was the colours of cements, bricks, greyish or something like that, and there was no tree, at least none that I could remember).
The dog following the bird wasn't the kind that could talk, as far as I remember. He behaved like... a dog, I guess. I'm not even sure what he looked like anymore, though I think it wasn't Hector the Bulldog (maybe a dog that looked more like the Barnyard Dog, willoughby, or maybe a smaller dog like the Frisky Puppy).
The bird was a very minor character in that episode. I'd like to describe it as a cameo appearance, as he wasn't part of the story, just a bird passing by to confuse the dog.
I tried searching "looney tunes bird disappear behind light pole", which is what helped me find that the bird is actually named the "Minah Bird". But I coud not find anything about the scene I remember.