title: Seventy-five years of masting and rodent population peaks in Norway: Why do wood mice not follow the rules?
abstract: Wood mouse (Apodemus sylvaticus) populations are expected to show a peak in autumn in the year after a mast year of sessile oak (Quercus petraea), because stored acorns increase winter survival. In Aust-Agder, South Norway, only 16 of 34 mast years from 1939-2014 were followed by a year with a peak in the wood mouse population. For many of the remaining instances, there rather was a minor peak 2 or 3 years after the mast. In multiple logistic regression models, the probability of a wood mouse population peak after a mast year of sessile oak was positively related to a snow-corrected temperature index of the previous winter and negatively to a small rodent population index of the previous autumn. The present study thus supports the hypothesis that longer periods with snow-free ground and subzero temperatures negatively affect wood mouse winter survival. Because it may be difficult for wood mice to survive on a diet consisting of acorns alone, the negative relationship with the rodent population index of the previous year is most likely caused by an over-exploitation of necessary alternative food resources, such as other plant seeds and arthropods. Stored acorns not utilized during one winter are assumed to benefit wood mice in a succeeding winter, giving a delayed population peak relative to the mast year.
authors.affiliation: Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, Ås, Norway. vidar.selas@nmbu.no.
authors.forename: Vidar
authors.initials: V
authors.lastname: Selås
mesh_terms: D000818:Animals; D016015:Logistic Models; D051189:Murinae / Q000502:physiology*; D009664:Norway; D011157:Population Dynamics; D029963:Quercus / Q000502:physiology*; D012621:Seasons; D012639:Seeds; D013696:Temperature
keywords: acorns; masting; seed production; winter temperature; wood mouse