ATTRACTION OF LIOMYS MICE TO HORSE DUNG AND THE EXTINCTION OF TIDS RESPONSE

Abstract

When horse dung containing the large seeds of Enterolobium cyclocarpum (the guanacaste tree) was experimentally placed in a tropical deciduous forest in Costa Rica (Santa Rosa National Park), Liomys salvini (Heteromyidae) spiny pocket mice went to it and dug out the seeds. When the Liomys in a particular area were repeatedly offered dung containing E. cyclocarpum seeds, they developed an attraction response to the dung that was so strong that seed-free fresh horse dung made better bait in traps than did an oatmeal-peanut butter mix. A single exposure to seed-rich dung was not adequate to generate this response, but two exposures generated a mild response. Once moderately seed-rich dung was no longer forthcoming, the mice in an area lost their strong attraction to horse dung in 3 to 4 months; this loss was due at least in part to the mice learning that the dung no longer contained seeds, since the same individual mice that earlier had been attracted to horse dung were still present as demonstrated by capturing them with other baits.