A simple method for tracking vertebrate-dispersed seeds

Tracking vertebrate-dispersed seeds from parent plant to deposition site re mains a primary obstacle to understanding the ecological and evolutionary c onsequences of seed dispersal. We evaluate a new and simple technique for t racking seeds. Fluorescent microspheres (15 mu m diameter) are applied to f ruits and later recovered in fecal material associated with the fruits' see ds. Trials with captive Cedar Waxwings (Bombycilla cedrorum) demonstrated t hat (1) percentage recovery of microspheres is high, (2) all defecations co ntaining seeds also contain microspheres, (3) relatively few microspheres a re recovered in defecations not containing seeds, and (4) presence of micro spheres on fruits does not affect fruit choice. Field trials with five spec ies of fruits demonstrated that, after similar to 30 d under full sun and h igh temperatures, photodegradation limits one's ability to detect microsphe res, The field trials also showed that an anti-transpirant applied with the microspheres allows them to adhere to fruits without deterring fruit consu mption or damaging fruits and that microspheres can be found in fecal sampl es of wild birds. Our technique is likely to be applicable to any study in which it is necessary to link fecal material with a particular source of fo od or an individual animal.