i think the focus on this picture is the animal, so it doesn't fit really into this contest. ok, there is rost in it but i think it shoub be focused on if you have such a theme

Cute !!

I like this photo despite its not being loudly about rust, but, IMHO, it could be so much better--so much that I think it could be a featured image although I don't think it will make it as is...we'll see.

This is a good photograph of a rusty-colored lizard in a textured, dimensional scene that is enhanced by dramatic, long shadows. Hoping not to offend, these are the elements, in my opinion that keep it from being a superior image.

Vignetting: It seems that the vignetting, darkening the corners and edges, is overdone, probably using the vignetting feature in Photoshop. If so, you could have used alternative methods that would have provided a more natural and subtle quality without losing contrast in the shadow areas and detail in the highlights.

Center of image: The approximate center of the image is the head of the spike that is holding the rail in place--and a fine spike head it is. Okay, you are trying to capture a shot before the lizard runs off--I'm just saying that having the spike head dead center doesn't help.

Perspective/separation of tones: If you had shot from just a few inches lower, you would have had much better separation and contrast between the top of the timber in the foreground and the shadow area of the timber in the back...hiding the distracting little highlights of gravel that don't contribute to the impact of the photograph. I, too, would have grabbed the shot, but if the lizard didn't panic and run, I'd look carefully for this and the other items I mentioned above in the hope of make a second shot better than the first.

Lizard: The dark line along the left side of the lizard seems artificial--is it an artifact of processing? something else?

Again, I'm making these extended comments not to pick on this image but because you have a good photo here that could be much better.