JackHammer
Chumono
Anecdotally, I disagree. The bird manure has a lot of ammonia which may be the issue in that case. For the dog - my dog pees in the same spot and it is the most luscious grass in the whole yard. That could be the extra frequent waterings though.It's not a quick simple answer.
The answer is in the links I posted but not directly
The center is where the droppings landed in concentration. The form of nitrogen in the droppings is in a form not easily used by plants and in fact burns the plants so they die
As you move out from the center, the concentration goes down as the nitrogen leaches out and is converted to more usable forms of nitrogen through decomposition by microbes and the nitrogen cycle happens.. Where you see the strong growth is where the toxic forms of nitrogen are gone and the highest concentration of usable nitrogen is so you get the most lush growth.
Similar happens when a dog urinates on the lawn just usually a bigger dead spot.
Not saying you are wrong, but I have had different experiences.