SUCKLING BEHAVIOR OF PINE VOLES (MICROTUS PINETORUM)

The suckling behavior of some mammals is characterized by preferences for anterior or posterior nipples and consistent return by individual young to particular nipples or nipple pairs. Some murid species also display tenacious nipple attachment. Pine voles (= woodland voles, Microtus pinetorum) have tenaciously clinging young and 2 pairs of abdominal mammae. We examined whether young pine voles preferred particular nipple pairs and whether young on the 2 pairs were differentially groomed or dislodged by their mothers. We also examined whether young showed fidelity to suckling location. Young pine voles preferred the hindmost nipples and were dislodged less frequently from those nipples than from the more anterior pair. We found no evidence that mothers differentially groomed young on the 2 pairs. Fidelity to nipple and nipple pair was greater in small than in large litters, which may reflect less competition for hind nipples in small litters and the need to consistently stimulate a nipple to ensure productivity.