These blocked channels then collect detritus and the water flow is altered. In time sand may collect against the detritus and slowly a new island forms as the path of the water is diverted around the blockage.
The paths cleared by the Hippo in thick vegetation such as papyrus are used by man and other animals alike and over time these paths are widened and are then used by other animals as crossing points between islands.
The Okavango Delta is a vast area but territorial disputes are very common in many species, and in particular with the water dependent creatures such as Hippo. Hippo males are very territorial and the sounds of disputes between males are common Okavango sounds. These disputes reach their peaks at the height of the dry season and the height of the high flood waters - for different reasons.
As the floodwaters recede the floodplains dry up and Hippo head north to areas of more permanent water - where they come into contact with the territorial males of the area. As more and more Hippo move into the northern areas the territorial disputes increase.
With the arrival of the floodwaters some Hippo move south with the water, releasing the pressure on the northern pods. As the floodwaters rise and the floodplains are covered with water the availability of grass diminishes - it is the dry season so the islands are dry and dusty - leading to skirmishes for feeding territories. This is, however, lessened by the availability of water grasses that grow with the water.
Many people living along the waterways of Africa have a healthy respect for the Hippo, and statistically it is responsible for more human deaths in Africa annually than any other wild animal, but the majority of incidents are the result of human fault.
Having mentioned the dangers Hippos pose it is essential to mention that the people of the Okavango have grown up with Hippos and they understand their behavior, and the inner workings of the Delta as a whole, and are the ideal guides for Makoro [dugout canoes] excursions.