Osprey Fighting Over Nest

I found 4 Ospreys fighting over this nest on an Osprey Platform along the Wildlife Drive. 2 Males & 2 Females. I assume it was about the nest, but maybe a territorial dispute. Thy were fun to watch as it went on for over 10 minutes. Most of the action was either very high in the sky or far away over the water. Even if I could not get a lot of close shots, it was fun to watch the action.