Potential of red deer (Cervus elaphus) to disperse viable seeds by spitting them from the cud

Most studies and reviews on endozoochorous seed dispersal by ungulates overlook that ruminants spit viable seeds from the cud, i.e. after they were ingested and carried inside the rumen. To assess the importance of this modality of endozoochory, we performed feeding trials with three captive red deer (Cervus elaphus) and four common plant species (Chamaerops humilis, Crataegus monogyna, Celtis australis and Ceratonia siliqua) differing in fruit and seed traits. Experimental deer regurgitated seeds from the rumen and ejected them, and also defecated some seeds of the four species, at a ratio of about 6:10. This high ratio (about 37%) of spitted seeds would be overlooked by studies considering only dispersal of seeds contained in faeces.