SCENT COUNTER-MARKING BY MALE MEADOW VOLES - FEMALES PREFER THE TOP-SCENT MALE

Scent counter-marking, in which one individual deposits scent in close proximity to the scent of another individual, is a widespread bur poo rly understood aspect of olfactory communication. Recent work with gol den hamsters suggests that animals may have specially evolved mechanis ms for determining which individual has marked most recently, and this work emphasizes the need for studies with other species. In Experimen t 1 it was shown for the first time that male meadow voles, Microtus p ennsylvanicus, scent mark with urine and anogenital scents and probabl y also counter-mark with these scents. Female meadow voles, after inve stigation of an area marked by two males, preferred the whole-body odo urs of the male that had marked the arena most recently (Experiment 2) . After females investigated a male's home cage that had just been mar ked by another male, they again preferred the whole-body odours of the male that had marked in the cage most recently (Experiment 3). These results demonstrate that female voles,like male hamsters, can distingu ish the top or most recent individual's scent from the bottom or older scent in places marked by two males, and further indicate that female voles may prefer the individual that deposited the top scent. Taken t ogether, the results suggest that counter-marking by male voles may be a type of competitive advertising and that females may base mate-chok e decisions on information from the pattern of such counter-marks.