Hippos are a very interesting species. Like most species; the hippo population grows at a logistic rate.
In every environment there are limited resources. This limit is called the carrying capacity. In logistic growth populations rise at a slow rate and then rapidly until it reaches a state where it stays the same which is called a plateau.
In a hippo population hippos do not have very many predators and are pretty versatile when it comes to eating. This means that they will reach a high rate but will eventually reach there plateau. Things like an increase in a lion population or a decrease in fertile grass will cause hippos to reach their plateau and stop the population from growing.
This is a picture of a hippo eating grass in its environment
Other factors that determine hippo population include immigration, emigration, birthrate, and death-rate. If Lions are immigrating into an area where there are a lot of hippos, then the hippo population will go down due to lions being predictors to hippos.
Since grass that is by the water are hippos first choice of food; if there is no grass in the area then hippos will emigrate from that place and immigrate to another body of water where there is grass. In fact hippos do this quite often since they eat a very large amount of food.
Birth is also a very big role in population count when it comes to hippos. Like humans, hippos typically have one child/calf at a time unless there are twins. This means that hippo populations are pretty low since most animals produce around 3 or four children a pregnancy. Birthrate increases if there is plenty of resources for the hippos.
Death- Even though the birthrate for hippos are low; hippos are very tough animals that have a very good chance of survival. Hippos have big jaws and are very protective of their young. Female hippos are known to bite down on an alligators to protect their young. This causes the population of hippos to go up. When death happens resources for other hippos open up.
This is a picture that shows hippos big jaws that they use to protect their young
Density-defendant factors like predators and competition are big factors on hippo populations. If there are a lot of predators then many hippos will die. If there are too many hippos and not enough food then hippos will either relocate or die.
Density-Independent factors also have a big role. Storms and can be be very harmful to hippos and can kill many of them. Habitat destruction has a huge role in hippo population because hippos are very picky about their environment. However, floods and high temperature does not have a very big impact on hippos because hippos are very good swimmers. Hippos also produce a oil on their bodies that act as a sunscreen for them and protects them.
This is a picture of hippos in their environment. This picture includes a very young hippo.