Unchecked international trade in wildlife threatens biodiversity globally. The major mechanism for regulating
this trade is listing species in the appendices of CITES, the Convention on International Trade in Endangered
Species. However, piecemeal protection of species in decline can displace demand onto similar, unprotected
species. In this study, we consider the case of the hornbills (Bucorvidae and Bucerotidae). Most Asian hornbills
received CITES protection in 1992, while international trade in African hornbills remains unregulated and underdocumented.
We analyzed data collected by the US Fish & Wildlife Service on 573 shipments of at least 2704
hornbills from 1999 to 2024. African species accounted for 94.5 % of traded hornbills. Trade in African hornbills
has increased significantly over time, unlike the trade volume of Asian hornbills, which has remained constant
under CITES management. Larger forest hornbill skulls are often sold online as oddities, while the smaller species
are advertised as pets. Current US trade in the larger African genera Ceratogymna and Bycanistes likely exceeds
global trade in all Asian hornbills prior to their CITES protection. Trade in the already Vulnerable Yellowcasqued
Hornbill and Brown-cheeked Hornbill currently poses an existential threat to these species. However,
every African genus of hornbill is traded internationally. To avoid shifting demand onto a few remaining