Screaming elephant-cousin threatened by logging
March 3, 2008
Surveying populations of the eastern tree hyrax (Dendrohyrax validus) in the montane forests of Tanzania, Elmer Topp-Jørgensen and colleagues found a correlation between hyrax density and the amount of forest disturbance.
"We estimate densities of 17.3 calling individuals ha-1 in a little-disturbed forest, 12.1 in a lightly disturbed forest, and zero in an intensely hunted and formerly logged forest," write the authors.
Topp-Jørgensen and colleagues say that in degraded forests, hyrax may find fewer tree cavities for shelter, increasing their vulnerability to predators and snares set by hunters.
Hyrax in Kenya. Photo by Rhett A. Butler.
"It has been suggested that selective logging could help finance tree hyrax conservation by logging only tree species not used for shelter or food," write the authors. "However in light of the D. validus relationship with canopy cover, the role of forest structure should be investigated more closely. This is particularly important in areas with significant ground trapping, where the resulting forest structure change (regardless of the species logged), may reduce hyrax density and thus counteract conservation efforts."
Topp-Jørgensen and colleagues suggest that active management of forest reserves could improve the outlook for hyrax and other forest-dependent species.
"Typically, forest reserves are not considered part of the global protected area network... Here we have demonstrated the major reason why, i.e., forest reserves are protected by legislation but not by active management. As a result illegal activities such as hunting and pole-cutting can continue unabated and unquantified. The effect seen here for hyraxes has been mirrored by several other taxa in the Udzungwa Mountains," they continue. "The creation of Kilombero Nature Reserve  and initiation of joint forest management, since conducting our surveys, opens the future possibility for monitoring the effect of management intervention"
The eastern tree hyrax weighs 4.5-11 pounds (2-5 kg) and reaches a length of 2 1/2 feet (70 cm). Males are known for their piercing scream, usually heard at night.
Topp-Jørgensen, J. E., Marshall, A. R., Brink, H. and Pedersen, U. B. 2008. Quantifying the response of tree hyraxes (Dendrohyrax validus) to human disturbance in the Udzungwa Mountains, Tanzania. Tropical Conservation Science 1 (1):63-74.