short story where all hard surfaces are destroyed by the droppings of an alien bird

I read a short story many years ago with a twist ending similar to Ray Bradbury stories. the story was post apocalyptic and the ending involved a strange alien bird like creature that poos on the road Tarmac and a plant begins to grow that cracks and destroys the road. The implication being that the birds presence has led to the end of the world as we know it because all concrete etc has been destroyed. I was reading a lot of Bradbury and Allen Dean Foster at the time so it could have been them but I have never come across the story again despite searching every few years.