Why is the Goliath heron so big ?
The Goliath heron (Ardea goliath) is the world's largest heron, with the exception of the extinct Bennu Heron (Ardea bennuides) which could grow up to 2 meters in size. The Goliath heron itself can reach a height of 120-152 cm. The Goliath heron catches fishes of a large size. Goliath herons catch an average of 2.3 fish per day weighing 500-600 g per fish. These large fish are very energy-efficient. Thus, the heron needs to catch only a relatively low number of fish per day.
One of the important questions is why that the Goliath heron is so large. Because of their size body, the Goliath heron can easily catch these large fish. But what has led this heron to start catching these large fish? One possible explanation is interspecific competition. For example, it is not physically possible for small herons to catch large fish. The Goliath heron was able to do so which, over the course of evolution, increased its body size. In this explanation, the Goliath herons were "forced" to hunt larger fish this due to the competition present.
On the other hand, the Goliath heron may also have made the choice on its own to hunt larger fish, this since larger fish are more energy efficient. This made it easier for the heron to meet its energy needs. Finally, their body size helps to ward off kleptoparasitism. Thus, African fish eagles, pelicans and crocodiles will try to steal the heron's prey.
