Tropical Forest Fragmentation and the Local Extinction of Understory Birds in the Eastern Usambara Mountains, Tanzania

Abstract. Small tropical forest fragments in the Eastern Usambara Mountains have lost understory bird species following forest fragmentation. The local extinction of these species is documented through a comparison of species number on nine smaller fores t fragments with species number on a tenth larger control forest site. The number of species captured in the control forest site is significantly larger than the number captured in eight of the nine smaller forest fragments under an equivalent capture effort. Forest‐dependent understory species vary greatly in their vulnerability to forest fragmentation. Relatively rare species and forest interior species are the avifauna most adversely affected by forest fragmentation. A concerted effort should be made to protect the existing corridors of native forest that link established forest reserves in the Eastern Usambara Mountains. Copyright © 1991, Wiley Blackwell. All rights reserved