|dc.contributor.author||Smith, Thomas B.
Whitney, Kenneth D.
Conservation of tropical forests requires an understanding of the seasonal patterns of abundance and
distribution of important seed dispersers. In the forests of Central Africa, three species of hornbills
in the genus Ceratogymna (Aves: Bucerotidae) provide dispersal for over 50 species of trees and
lianas, yet their ecology is poorly known. We present the first empirical evidence for resource tracking
and large-scale movements by two of these species, which were previously considered resident.
Hornbill numbers and fruit production were estimated over a one-year period in the Dja Reserve,
Cameroon. Monthly abundances of C. atrata and C. cylindricus varied four- and 12-fold, respectively,
and were predicted by community fruit availability as measured by fruitfall on a 4·3 km trail. In contrast,
C. fistulator abundances varied little and were not related to fruit availability. Synchronous population
fluctuations in sites 22 km distant were observed for atrata and cylindricus, but not for
fistulator. Together, these results indicate that atrata and cylindricus populations track fruit resources
via seasonal emigrations, while the fistulator population appears to be relatively sedentary.
Comparisons of hornbill densities in primary and secondary forests suggest that they are important
dispersers in both habitats, and will likely play larger roles in central African forest regeneration as
more vulnerable seed dispersers are removed by hunting. If large seasonal movements of hornbills
turn out to be a general phenomenon, effective management of central African forest reserves will
require greater emphasis on reserve connectivity and on seasonal and spatial patterns of fruit
NYZS/The Wildlife Conservation Society, the National Science Foundation Graduate Fellowship
Program, San Francisco State University, and ECOFAC Cameroun
Habitat use and resource tracking by African Ceratogymna hornbills: implications for seed dispersal and forest conservation