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.
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].
OCENA LICZBY URODZONYCH MŁODYCH WEDŁUG BLIZN ŁOŻYSKOWYCH U MYSZY LABORATORYJNEJComparison was made between the number of placental scars and the number of young born, in 96 females which previously had produced one, two or three litters. Placental scars were counted at autopsy on uteri in fresh state as well as after fixation and bleaching. Bleaching of uteri does not improve the legibility of scars. Scars remain visible on uterus for at least 9 months. In females breeding once or twice the number of scars exceeds the actual number of young born; in females breeding three times the cumulative number of young exeeds scars count thus resulting secondarily in approximation of the mean number of scars and young born. Up to the 10th day of pregnancy it is possible to determine if the female bred previously. Value of the correlation coefficient between the number of scars and young born decreases as the number of young born increases. In general counting the placental scars provides a reliable method of estimating the number of young born.The present investigations were undertaken in order to define the approximate error in estimating the number of young born to a female, on the basis of the placental scars count. Placental scars represent climps of hemosiderine derived from désintégration of red blood cells. They are situated between the longitudinal and the circular muscles of the uterus, as well as in the deeper layers of endometrium in places where placentae were situated.96 females from the inbred strains A, CBA, CBA-p, CBA-T6T6 were examined. The whole material was divided into four series: females which gave one litter (I), two litters (II), three litters (III), one or two litters and autopsied during a succesive pregnancy (IV).Females belonging to I series were dissected between the first and ninth months after giving birth. Females belonging to series II and III were autopsied two to five month after last breeding, and the interval between successive pregnancies amounted to several weeks. The size of litters was estimated on the first day after birth, before noon. These data are probably somewhat »underrated« because in some cases females could have eaten part of their litter before its number was recorded.Uteri were excised from the body, rinsed, stretched out on paraffin plates, and examined in 0.9% NaCl. Stretched out uteri were then submerged in 10% formaldehyde for 24 hours. After rinsing they were bleached out according to the method of Strauss (R o m e i s, 1953) using 5% KOH in 6%H 2 0 2 . Placental scars were examined and counted under 6.3 magnification of a dissecting microscope by transmitted and reflected light. The comparison was made between the number and position of scars on fresh and bleached out material. RESULTSThe analysis of the first series has shown that placental scars remain visible on uterus for at least 9 months after pregnancy. This observation confirms the results obtained by Deno (1941) and Davis' and E m 1 e n's (1948) with Mus musculus and Rattus norvegicus respectively. Accor...
Using material consisting of 127 individuals of Sorex araneus Linnaeus, 1758 (3 series from different years) it was shown by means of a micro-hardness tester that the enamel of tooth I 2 varies in hardness from 260 kg/mm 2 to 400 kg/mm 2 , with a mean value of 311 kg/mm 2 . The hardness of the enamel does not alter in different years or at different seasons of the year, and is the same in both males and females. The enamel is hardest on the surface of the tooth, and softest near the dentine. Dentine varies in hardness from 44.8 kg/mm 2 to 90.5 kg/mm 2 , being greatest at the borderline with the enamel at the front and back of the tooth, and least in the centre. Hardness of the dentine varies in series from different years, which has a significant effect on the rate of wear of the teeth, and hence on identification of the animals' age. There is a tendency for the dentine to be softer in individuals from the winter (older animals) than from the summer (very young animals).
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