Tropical rainforests cover only 7 % of the world’s land area, yet they hold the highest biodiversity of all habitats on earth and harbors over 50 % of all known species. Hence, tropical rainforests are irreplaceable reservoirs for biodiversity. One reason why tropical rainforests can hold such high biodiversity is their complex vegetation structure. As the physical complexity of the vegetation structure increases, so does the species richness of many animal groups. Birds are one such group, and the relationship between an increase in the complexity of the vegetation structure and an increase in species richness of birds is well documented.

Birds play important roles in the ecosystem they are part of. They contribute to pollination and seed dispersal, crucial for the successful reproduction of many plant and tree species, and act as pest control. However, how birds respond to vegetation structure and use the available resources is not entirely clear but partly depends on the species morphological and behavioral traits, e.g. their body sizes, foraging patterns, or breeding patterns. In other words, the bird species’ feeding- and habitat guild will partly determine how the species responds to changes in vegetation structure.

Human activities have led to tropical rainforests undergoing unprecedented changes, causing a severe loss in global biodiversity. Due to the loss and destruction of tropical rainforests, as much as approximately 70 % of the threatened bird species in the world are found there. 

The Kakamega forest is a tropical rainforest in western Kenya where local people, both legally and illegally, collect firewood which might contribute to deforestation and degradation of the forest. The Kakamega forest is also interesting from another point of view. It is known for its great diversity of birds, is home to globally threatened-, restricted-range- and biome-restricted species of birds and is therefore unique both nationally and internationally.