Жонгол тарбаганы популяцийн экологи-биологийн бутцийн онцлогБ Mongol tarbagany popoulyatsiïn ekologi-biologiïn bouttsiïn ontslog [Population structure of the Mongolian marmot. Structure de la population de la marmotte de Mongolie].

Résumé

Research on the population of the Mongolian marmot yielded the following results: 1. There were distinctly different habitats in the high mountain zone which influenced marmot population density. Marmot density in Ugalz Mountain demonstrated an increasing trend from the base of the mountain to the peak (r = 0.89). No data was collected on the marmot populations in the mountain’s steppe region. 2. There were 2 distinctive sections of the marmot population (center and edge) which differed with respect to population density, location, burrow size, state of burrow occupation, and family size. When mortality increase, migration increased from the center to the edge of the marmot population and density decreased on edge. 3. Embryonic sex ratio of Mongolian marmots differed in every population. The sex ratio of kits depended upon size, density, and mortality rates of the population. A higher percentage of female kits were born in population with higher mortality rates and a higher percentage male kits were born in populations with high densities and lower mortality. 4. In general, the sex ratio of Mongolian marmot populations were male dominated (mean 123 ±15 males : 100 females), however, this was not the populations with high mortality, particularly, populations within a plague focal area. 5. Mongolian marmots have survived 9+ years (wintered 9 times) in nature. Older marmots comprise only 1.0-1.2% of the majority of populations. 6. Female marmots can reach sexual maturity when they are 2 years old, but the percentage of 2-year old actually reproducing depends upon the density, size, mortality rate and over-all sex ratio of the population. 0.95 ± 1.9% of females 2+years old reproduced each year in a population within a plague focus area and with high density. The proportion of reproducing females increased to 15,8% in hunted populations free of plague. 7. The percentage of pregnant females was negatively correlated with population density (r = -1.0). The mean percentage of adult females mating or impregnated was 45.2 ± 7.6. 8. The mortality rate of kits was 33.8 ± 0.9% during the embryonic stage, 31.6 ± 2.5% during neonatal development, and 65.4% over-all from zygote until first hibernation. 9. The reproductive potential of the Mongolian marmot population was 60.0 ± 8.4% per year, but kit mortality was comparatively high. Therefore, reproductive potential beyond the first year was actually about 20%. Reproductive potential was negatively correlated with population density (r = -0.99) and positively correlated with the percentage of pregnant females (r = 0.96).