Zur Populationsökologie und Raumnutzung der Steppenwühlmaus Microtus brandti (Radde, 1861) in der Fortpflanzungsperiode

Authors

Ulrich Zöphel, Radebeul, GermanyFollow
N. Dawaa, National University of Mongolia

Date of this Version

2005

Document Type

Article

Citation

Erforschung biologischer Ressourcen der Mongolei (2005) 9: 261-272.

Proceedings of the symposium ”Ecosystem Research in the Arid Environments of Central Asia: Results, Challenges, and Perspectives,” Ulaanbaatar, Mongolia, June 23-24, 2004.

Results of the Mongolian-German Biological Expedition since 1962, No. 253.

Comments

Copyright 2005, Martin-Luther-Universität. Used by permission.

Abstract

During the growing season between 1988 and 1990 the population biology of Brandt’s vole (Microtus brandti) was observed in a population near Ulaanbaatar. Mark-recapture techniques (1,438 markings, 19,606 recaptures in total) and complementary methods were used. The density maximum was observed in July with 98 (1988); 169 (1989) and 94 (1990) individuals/ha and the population fluctuated by a factor of 7.4.

At the beginning of reproductive period the males disperse over a minimum distance of one female home range whereas the females do not migrate after winter. The typical mating system is promiscuity. Youngsters have been recorded from the beginning of May until the middle of August (rarely until the beginning of September). After hibernation the females can give birth three times during one season. Females born in May become sexually active after one month and give birth twice before the inset of winter. In contrast to that those females born in June or later reproduce only in the next year. On average one litter comprises 7.6 specimens with 5.4 getting independent. The fertility of females belonging to different cohorts (birth months) is significantly different. Reproductive males suppress the sexual maturation of the immature males usually until the next spring.

At the end of April on average 2 females (1-5) and 1 male (seldom up to 4 specimens) live at one winter burrow. The home range of an adult male is roughly 2,500 m² often overlapping those of neighboring males. The spatial demands of adult females are less with home range sizes of about 1,500 m². They raise their young in special nests - sometimes together with other females. In the middle of August the mother families (”Sippen”) start to defend territories with a diameter of 40 m. Within these areas the winter burrows are being built. For modelling population dynamics the different ecological strategies of the cohorts have to be taken into account. The understanding of the population cycles requires the combination of the investigations of sub-populations with observations at the population level.