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Nabaglo L., 1986: Common vole numbers in relation to the utilization of burrow systems. Acta theriol., 31, 2: 17-44 [With 2 Tables & 17 Figs.] Population dynamics of the common vole Microtus arvalis (Pallas, 1779), changes in the number of burrow systems, and their utilization were studied in perennial crops of different regions of Poland in [1970][1971][1972][1973][1974][1975][1976][1977][1978][1979]. A multi-year cycle in common vole numbers was found. In the northern region of Poland, maximum peak numbers reached 350 individuals/ha, and in the southern region more than 1000 individuals/ha. An increase in common vole numbers in the multi-year cycle was positively correlated with the number of burrow systems. Highest increases in common vole numbers were observed in autumn, and lowest in spring. Per unit increase in the number of burrow systems, the rate of growth in common vole number increased in the years of peak numbers and decreased in the years of decline. The percentage of occupied burrow systems (colonies) and the number of individuals per burrow system increased with growing population size, but at a declining rate. Multi-year and annual changes in common vole numbers were more affected by changes in the number of occupied burrow systems than by changes in the number of individuals per system. Only in the periods of numbers decline, they mostly depended on changes in the density of colony members. The factors underlying differences in mean numbers of M. arvalis in different regions of Poland are discussed.

Ciężar soczewki oka jako w skaźnik wieku u myszy leśnej Leszek NABAGŁO & Karol PACHINGER Nabaglo L. & Pachinger K., 1979: Eye lens w eight as an age indicator in yellow-necked mice. Acta theriol., 24, 11: 118-122 [With 3 Tables & 1 Fig.] Relations between age classes determined according to degree of wear of m olars and eye lens w eight w ere evaluated for Apodemus flavicollis (Melchior, 1834). Taking the eye lens as an indicator of age, it proved possible to distinguish age class which could not be determined by the tooth wear method. There w as also a shift of individuals from age class III, determined on the basis of tooth wear, towards the older age classes. Increase in eye lens weigth in age classes was brought closer to the true age o f individuals.

Nabagło L., 1977: Demographic parameters and variations in numbers of the common vole. Acta theriol., 22,.Observations were made for two years of the demographic variations in two enclosed populations (A and B) of the common vole Microtus arvalis (Pallas, 1779), by means of the CMR method. Variations in numbers followed a similar course in both populations, population A reaching a lower maximum number than B. Both populations were more numerous in the second study year (1972). The greatest rate of increase in numbers (tn = 0.23) took place in May. Maximum increase was found in the number of individuals (f r =0.5-1.0/week/l $) during the period from May to July. In the early summer period the rate of increase in numbers in the populations was found to be limited by the high degree of mortality among the youngest animals. During the reproductive period turnover was 60%-90°/o of the population per month. The ratio of females to males in the population varied from 0.25 to 2.35. The greatest percentage of females was observed during the period of intensive reproduction, and was correlated with the number of recruits to the population. The predominance of females results in higher recruitment and better survival. During the growing season over 60% of the population was formed by individuals which had spent less than one month outside the nest. During autumn of the year with higher numbers the populations were younger than was the case in the year with lower numbers. The more numerous population (B) was younger than the less numerous (A). During the reproductive period the females were older than the males. The study populations were in the phase of rapid population growth, which was accompanied in successive years by longer-lasting numerical predominance of females over males, prolongation of the reproductive period and better survival of new individuals.[Inst. Ecol., Polish Acad. Sci., Dziekanów Leśny, 05-150 Łomianki, Poland].

1Leszek NABAGŁO Nabagło L., Demographic processes in a confined population of the common vole. Acta theriol., 26, 9: 163-183 [With 1 Table & 9 Figs].Studies were made on populations of Microtus arvalis confined in two-hectare fields of alfalfa and rape to ascertain to what degree rumbers and variations in demographic parameters depend on habitat factors connected with the species of crop, and to what degree on intrapopulation conditions. The numbers of voles were greater in the alfalfa field than in the rape. Differentiation in the level of numbers took place by means of variations in mortality rate. From August to October 1976 voles in the rape field exhibited reduction in reproduction potential and better capacity for survival than voles in the alfalfa field. The following periods were distinguished in respect of variations in numbers of the two populations over the course of a year: (1) increase; (2) stabilization; (3) winter decrease. The relation between rate of growth in numbers and density in successive periods was as follows: positive, negative and absence of relation. Intensity of recruitment was lesser in the population in the rape field during the stabilized period than that of increase in numbers, whereas in the alfalfa field it was similar in both periods. Mortality rate was higher in both populations during the stabilization period than during the increase period. Mortality among the voles was higher in winter in the alfalfa field. The controling character of the influence of the environment on the level of numbers and the regulating effect of density on mortality are discussed, as are also variations in turnover rate reflecting elements of the population maintenance expenditure, depending on habitat conditions.[Inst. Ecol., Polish Acad. Sci., Dziekanów Leśny, 05-150 Łomianki, Poland].