Double-crested Rookery

 

These Double-crested Cormorants created this rookery out in Heislerville, New Jersey on their own. How did they do that? Their guano is acidic and changed the soil chemistry around the trees, killing them and all the ground vegetation nearby. Hard for snakes and other predators to slip in unseen. It kills the trees but allows the Cormorants a safe place to raise their young. In nature, as in other places in life, tradeoffs are everywhere.