WHAT FOOD DOES GORILLAS FEED ON
What gorillas eat depends on what
their habitat provides and on the time of the year. Mountain gorillas mainly
feed on green plant parts, whereas lowland gorillas eat a lot of fruit.
However, in the dry season only a few juicy fruits are available and so the
animals have to eat more seeds and tree bark instead. Usually, fruits grow on
trees; gorillas of all ages climb these trees to harvest them. Although western
gorillas eat a higher percentage of fruit than of leaves, stems, pith and
shoots, they still eat markedly less fruit than do chimpanzees and orangutans.
The food range of the western
gorillas is very broad: they eat about 200 plant species. They particularly
like plants belonging to the ginger and arrowroot families. In contrast, the
mountain gorillas in the Virunga Volcanoes eat only 38 different plant species,
mainly Galium, thistles, celery and nettles.
An adult Grauer's gorilla male is
estimated to eat 30 kg of plants every day, an adult female about 18 kg. To be
able to process these masses of plant material, gorillas have very strong
chewing muscles. Their teeth are much like human teeth, except for the very
long, pointed canines of adult gorilla males. The males do not use those for
feeding but for fighting against competing males.
Apart from plants, they ingest soil occasionally. Perhaps this soil contains minerals that are missing in their plants, or the minerals neutralize poisonous substances in their food.
Although gorillas don't kill big animals, they regularly eat small animals (mainly insects). However, this constitutes far less than 0.1% of their food. In chimpanzees, up to 6% of the food may be animal matter.
Apart from plants, they ingest soil occasionally. Perhaps this soil contains minerals that are missing in their plants, or the minerals neutralize poisonous substances in their food.
Although gorillas don't kill big animals, they regularly eat small animals (mainly insects). However, this constitutes far less than 0.1% of their food. In chimpanzees, up to 6% of the food may be animal matter.
A study in Cameroon by Isra Deblauwe
showed that gorillas have a high frequency of insect-eating and a high prey
diversity, even higher than those for the sympatric chimpanzees. There are
important differences in the nutritional composition of the gorilla and
chimpanzee termite prey species. Gorillas select termites high in iron and ash
with possible anti-diarrhoeal characteristics. Termite eating in western
lowland gorillas might therefore be a high quality alternative for geophagy.
Gorillas eat different insect
species in different regions; there may even be traditions in prey choice.
Where does gorillas live
Gorillas live exclusively in the tropical rain forests of Africa. Their distribution range is divided into two parts - almost 900 km separates the western and the eastern gorillas. The reason for this is probably that a formerly uniform area was split at some point, most likely during the ice ages. At that time, climatic changes caused the rain forest to shrink into a few refuge areas. The savannah, which spread between these refuge areas, was not an appropriate habitat for gorillas. Later, when the rain forest spread again over the whole of the African tropics, gorillas could only advance to the Ubangi and Congo Rivers.As western and eastern gorillas have been separated for such a long time, they have followed separate development paths. Today, they differ distinctly both in their external characteristics and in their genetic material.
Although the borders of the gorillas' distribution area seem to have changed little over the last few decades, the habitat of this ape species has been fragmented and encroached considerably as forested areas are increasingly reduced and isolated from each other by cultivation. From some regions gorillas have already disappeared altogether because the forest has been destroyed. Therefore they often are confined in small and isolated forest islands.
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