The demography ofClethrionomys rufocanus: From mathematical and statistical models to further field studies

Abstract

Until recently, most studies on microtines have focused on patterns in population dynamics or demography without providing a quantitative assessment of the robustness of the inferred patterns as well as a link between demography and population dynamics. Developments in statistical timeseries analysis on the one hand and in capture-recapture statistical modelling on the other hand, now allow for improved analyses. We review some of the recent developments in the capture-recapture statistical methodology -restricting ourselves to methods most relevant to the demography of small mammals. A 5-years study of the gray-sided vole Clethrionomys rufocanus in Hokkaido, Japan was used as an example to explore some models. We then provided a framework for further demographic analysis of microtine populations, including C. rufocanus. Investigating the relative importance of the different demographic parameters (e.g. survival, maturation, dispersal) will require studies done on larger scale than is commonly done today, with more effort devoted to the low density phase. Special emphasis is given to study-design, and to experimental designs tailored to the study of specific demographic mechanisms.

Impact of Puumala Virus Infection on Maturation and Survival in Bank Voles: A Capture-Mark-Recapture Analysis

“…Additionally, because of unequal time intervals between trapping sessions, we standardized all survival probabilities to 28 days, which is a reasonable time interval for small mammal survival estimates (Yoccoz et al, 1998).…”

“…For modeling recapture and survival probabilities, however, temporal and spatial variation was taken into account. Temporal variation was modeled by including season (summer, spring, autumn) and year (2004-06) because both scales have been stressed in previous small-mammal demographic studies (Yoccoz et al, 1998;Crespin et al, 2002). Furthermore, fully time-dependent models (i.e., with five values for each parameter) were run, as 3 yr of data may be insufficient to detect both seasonal and intra-annual variation.…”

A model for the transmission of Echinococcus multilocularis in Hokkaido, Japan

“…The maturation period is about 30-60 days, and the gestation period is 18-19 days (Abe, 1968). A typical litter size is 4-7, with an average of 5.3 (Fujimaki, 1981;Yoccoz et al, 1998), and the order of decreasing litter size was reported as spring, autumn and summer (Fujimaki, 1975). The percentage of breeding females is higher in spring and autumn than in summer (Ota, 1984).…”

Kin‐related social organization in a winter population of the vole Clethrionomys rufocanus

“…In future studies, therefore, both effects of kinship and familiarity on survival and reproductive success should be considered. Furthermore, the present findings that immature fall-born females stayed at their natal site and survived the winter, whereas most reproductively active fall-born females dispersed from their natal site in the fall and died during the winter, may be one of the keys to understand density-dependent decline of vole populations in winter Yoccoz et al 1998). Since the breeding season is shortened in high density populations (Fujimaki 1969;Abe 1976), the proportion of fall-borns may be comparatively small during peak years.…”

“…Although fall abundance varies greatly from year-to-year, abundance is less variable in spring (Saitoh 1987;Saitoh et al 1998a). This implies that both rates of winter decline and summer increase differ among years (see also Yoccoz et al 1998). The density-dependent process during the winter may be particularly important .…”