Deforestation and bird species composition in Liberia, West Africa

Abstract

Liberia lies entirely within the Upper Guinea rain forest belt of tropical West Africa. The Upper Guinea rain forest, with 22 endemic bird species, is a major area of endemism for birds in Africa. Despite extensive deforestation, Liberia still contains the two largest tracts of forest, comprising 50% of the remaining Upper Guinea rain forest (ALLPORT 1991). The historical and present trends of deforestation in the country are reviewed.

Bird species were recorded at two sites in Liberia: one in the undisturbed rain forest interior away from the edge, and one in middle of the adjacent deforested zone. In addition, we use lists of birds recorded at two other sites in Liberia: a selectively-logged rain forest (KARR 1976); and one in the periphery of the coastal deforested zone but proximal to a major rain forest block (BLANKESPOOR 1991). To quantify the effect of deforestation on the Upper Guinea bird fauna, pairwise indices of similarity were calculated between the bird communities. The similarity index between the bird communities of the rain forest sites and the deforested sites was 0.276.

The clearest impact of destruction of the Upper Guinea rain forest on its bird communities is a dramatic change in species composition, and probably also a decrease in species number BLANKESPOOR 1991). With selective logging, about 1/3 of the rain forest bird species can be expected to disappear. Seventy percent of the rain forest species were absent from the deforested sites, presumably extirpated by deforestation. The Little Greenbul (Pycnonotus virens) was the most common species in both the rain forest interior and deforested zone. Only a few rain forest birds are preadapted for inhabiting and reproducing in secondary growth in the deforested zone (e.g. the Little Greenbul); a few can survive in rain forest fragments, and a few canopy species can survive where there are patches of tall trees. Most species of rain forest birds are unable to survive and establish viable populations in the deforested zone.

More additions to the avifauna are expected as species new to Liberia continue to arrive from neighbouring savannas, and Palaearctic migrants extend their winter ranges further south. The frequency of Palaearctic migrants within the rain forest is likely to increase as the forest becomes more fragmented.

Continued destruction of the rain forest in Liberia seems inevitable. It is vital, therefore, that future international efforts focus on Liberia if the biodiversity of the Upper Guinea rain forest is to be conserved.

Key Words:

• Africa
• birds
• deforestation
• Liberia
• rain forest
• Upper Guinea
• West Africa