Abstract:
Costa Rican horses ranging free in deciduous forest-grassland habitats swallow about
half of the seeds in the Enterolohilrnz c.xc/oc,clrputn fruits that they eat. and six such horses defecated
at least 9-56% of the seeds alive. While about three-quarters of the surviving seeds appeared by the
14th d after ingestion, about a quarter of the surviving seeds emerged 15-60 d after ingestion. The
horse kills Ent'rolohilr~n seeds by digestive processes shortly after the seed germinates in response
to the moisture of the intestinal tract. More than 9m of the seeds that survived the trip did so as
hard dormant seeds. They showed no indication that they would germinate more rapidly (break
dormancy more rapidly) than seeds planted directly from the fruits. The horse-seed interaction suggests
that Pleistocene horses may have contributed to both local and long-distance population recruitment
by fi~terolohiunz cxc/oc.urplrnz, and contemporary horses certainly have the potential to do
so.
