Objective To determine whether there is distribution of Rattus norvegicus within the Tibet Autonomous Region. Methods Rats were captured using mice traps and made into specimens. Results From July to October, 1974, 15 rat species were found and 80 specimens were made in Lhasa city and Shannan mount areas. A R. norvegicus was captured in Bayi town of Linzhi city, and the specimen is deposited in the Animal Specimen Collection of the Grassland Research Institute of Chinese Academy of Agricultural Sciences. The captured rat was male, 182 g in weight, 195 mm in body length, 167 mm in tail length, 34 mm in hind foot length, 20 mm in ear length, 43.4 mm in skull length, 42.0 mm in cranial base length, 17.5 mm in nasal bone length, 19.8 mm in zygomatic width, 6.7 mm in inter-orbital width, 18.5 mm in hind head width, 13.9 mm in toothspace, and 7.7 mm in upper dentition. The other R. norvegicus was captured in Cuona county on the southern slope of the Himalayas, whereas the specimen was not retained. Conclusion R. norvegicus was found in Linzhi and Cuona county.

【Abstract】 Objective Study the breeding ecology of desert hamster（Phodopus roborovskii）. Methods The population dynamics of P.roborovskii was investigated at different habitats in Ordos sand?land grassland in the middle ten days from April to October during 1991 to 1998 by rectilinear?trapping method. The trapped rodents were weighed, surveyed and dissected, and the breeding condition was recorded.  Results Ten kinds of rodents were captured from 1991 to 1998. The desert hamster was one of dominant species, which accounted for 30.93% of all captured rodents. A total of 2562 desert hamsters were captured, including 1258 females with the proportion of (49.10±1.94)%. There was no significant difference in sex ratios with the change of seasons and years. The average decreasing rate of testicle in male was (70.55±2.47)%, and it began to decrease in February, ending in October. Average pregnant rate and placenta rate were (26.39±2.43)% and (21.38±2.27)%, respectively. The average number of fetal rats and placenta were (6.23±0.18) and (5.38±0.49), respectively. The females that produced two times each year accounted for (4.13±1.10)%. Average reproduction index was 1.062±0.162. The reproduction period of females was from March to November. The decreasing rate of testicle in scrotum, pregnant rate and reproduction index had obvious changes with seasons and years. Conclusion There was significant difference among sex ratio, declining rate of testicle in scrotum, pregnant rate and fetal rats quantity of P.roborovskii with seasons and years.

Objective The regularity of population dynamics of mongolia five toed jerboa ( Allactaga sibirica) were studies in the central and western region of Inner Mongolia to provide the basis of prediction and control. Methods The population dynamics of mongolia five toed jerboa was investigated by rectilinear-trapping method in the middle ten days of each month from April to October in Hohhot suburbs,Dalate County and from May to September in Zhengxiangbai county. Results Mongolia five toed jerboa was the common species but the population number of them were less in Hohhot suburbs,Dalate county and Zhengxiangbai county. The seasonal fluctuation of mongdia five toea jerboa population were different in Hohhot suburbs,Dalat Xounty and Zhengxiangbai county. The seasonal fluctuation was the type of single peak and the peak of them was in spring season in Hohhot suburbs and Dalat county. The seasonal fluctuation was the type of double peak and the first peak was taller than second in Zhengxiangbai county. An annual fluctuation of population number were different in Hohhot suburbs,Dalat county and Zhengxiangbai county. The tallest in Hohhot suburbs,second with Zhengxiangbai county,and then with Dalate county. Conclusion The important elements affecting it's population dynamics are the pregnant rate,reproduction index and the population number of other species (northern three-toed jerboa,little Chinese jird,desert hamster and striped hamster) in the investigated region.

Objective The succession of rodent community were studies in Ordos sandland from 1991 to 1998. Methods The succession of rodent community was investigated on Ordos sandland by rectilinear-trapping method in the ten days of each month from April to October during 1991-1998. Results There are ten species of rodents on Ordos sandland.They are northern three-toed jerboa ( Dipus sagitta),mongolian five-toed jerboa ( Allactaga sibirica),three-toed pygmy jerboa ( Salpingotus kozlovi),desert hamster ( Phodopus roborovskii),little chinese jird ( Meriones meridianus),clawed jird ( Meriones unguiculatus),striped hamster(Cricetulus barabensis),daurian ground squirrel ( Spermophilus dauricus),norway rat ( Rattus norvegicus) and house mouse ( Mus musculus). The construction of rodent community was not different each year during 1991-1998. The dry-prefer rodent community ( Dipus sagitta,Phodopus roborovskii,Meriones meridianus) was substituted by moist-prefer rodent community ( Cricetulus barabensis). Conclusion The succession of rodent community arose from change of dwelled conditions in Ordos sandland.

Objective To study population dynamics of little Chinese jird ( Meriones meridianus) and its affecting elements. Methods The population dynamics of little Chinese jird was investigated by rectilinear-trap-day method in middle ten days of each month from April to October during 1991-1998. Results There are ten species of rodents in Dalate County during 1991-1998. Northern three toed jerboa ( Dipus sagitta),desert hamster( Phodopus roborovskii),little Chinese jird and striped hamster( Cricetulus barabensis) accounted for over 10%,respectively.The seasonal fluctuation has two peaks every year.In 1991-1998,the population dynamics fluctuated with low valley(1991),increase(1992),peak(1993-994),decrease(1995) and low valley(1996-1998)among 8 years. Annual capture rates are all under 2%, s(of logx,x=population density of M.meridianus)<0.5. Between the number of M.meridianusand pregnant rate, r=|-0.758|> r _0.05=0.754; Between the number and repregnant rate, r=0.827> r _0.05=0.811; Between capture rate in Oct.and capture rate in Apr. next year,r=0.759> r _0.05=0.754, df=5; Between the number of the jird and the number of D.sagitta, P.roborovskiiand C.barabensis,r=0.662( 0.05=0.707),0.762(> r _0.05=0.707)and0.498( r _0.05=0.707) respectively. Conclusion D.sagitta, P.roborovskii, M.meridianusand C.barabensisare the dominant rodent species in Dalate County in 1991-1998.The population number is maximum in March and in July. The annual fluctuation is not periodical. The important elements of population dynamics were the pregnant rate,the repregnant rates,reproduction index,the capture rate and the population number of other species ( D.sagitta, P.roborovskiiand C.barabensis).

Objective To study the efficiency for different density of pindone and pivalyn controlling clawed jird.Methods The poison bait was thrown at the entrance to caves.The methods for the efficiency controlling clawed jird marked by to stop up entrances to cove and to open it.Results The efficiencies for 0.022 5%,0.045% and 0.09% pivalyn bait are(95.75±3.33)%,(98.74±1.73)% and(97.34±2.57)% respectively against the clawed jird.The efficiencies for 0.025%,0.05% and 0.1% pindone bait are(90.41±5.16)%,(91.90±4.59)% and(93.39±3.13)% respectively against the clawed jird.The difference between the average efficiencies of pivalyn and pindone bait to controlling clawed jird is not remarkable( t=0.415< t _0.05=1.96),and the difference between efficiencies of pivalyn or pindone and bromadiolone is not remarkable either( t=0.058< t _0.05 =1.96 and t=0.412< t _0.05 =1.96 respectively).Conclusion The pindone and the piualyn are better anticoagulant.

Objective To study the ecological characteristics of striped hamster( Cricetulus barabesis) in the central and western region of Inner Mongolia.Methods The studies were carried out in Hohhot suburbs,Dalate County and Zhengxiangbai County in the middle ten days of each month from April to October in 1991 to 1998 by rectilinear trap day method.Results The striped hamster is one subspecies Cricetulus barabese obscurus in Hohhot suburbs,Dalate County and Zhengxiangbai County.The seasonal and annual changes in population number of striped hamster were varied from 1991 to 1998.The sex ratio of the females was 53.62% and the females accounted for a larger proportion than the males in Hohhot suburbs.The sex ratio of the females was 42.11% and the males accounted for alarger proportion than the females in Dalate County.The sex ratio of the females was 49.42% in Zhengxiangbai county.The rates of testis entering scrotum from abdominal cavity were(62.16±3.29)%,(38.53±3.45)% and(76.88±6.28)% respectively in Hohhot suburbs,Datate and Zhengxiangbai County.The annual average pregnant rat rates were(19.73±2.50)%,(23.06±3.50)% and(21.89±6.23)% respectively in Hohhot suburbs,Dalate and zhengxiangbai County.The annual average litter sizes of females were(5.96± 0.10)%,(5.77±0.16)% and(5.61±0.29)% respectively in Hohhot suburbs,Dalate and zhengxiangbai County from 1991 to 1998.Conclusion The ecological characteristics of striped hamster in the 3 counties are almost same in the central and western region of Inner Mongolia.

Objective The characteristics of population dynamics of clawed jird( Meriones unguiculatus Milne-Edwards) were studied.Methods The population size of the clawed jird was studied in the years of 1984-2002,from April to October at suburban areas of Huhhot,Inner Mongolia,by rectilinear trap-day method.Results The population size of the clawed jird underwent a cycle of “ steady- increase- peak- decrease-steady”.The rate of scrotal sac of male,pregnancy rate,the litter size,the numbers of placental scar and reproduction index was differentiated in the different periods of the population.Conclusion The studies on the characteristics of population dynamics of clawed jird present the basis for predicton and control of the clawed Jind.

Objective To study on the elements of population dynamics of desert hamster( Phodopus roborovskii).Methods The population dynamics of desert hamster was investigated on Ordos sandland by rectilinear-trapping method in the middle ten days of each month from April to October during 1991-1998.Results The desert hamster was the dominant species of rodents on Ordes sandland.The seasonal and annual fluctuation of its population number were different year to year.The populaion dynamics fluctuated with valley(1991-1992),peak(1993),decrease(1994)and valley(1995-1998) among the 8 years.Conclusion The important elements of population dynamics were the population age structure,the pregnant rate,the reproductive indices and the population number of other species(little Chinese jird,northern three-toed jerboa and striped hamster).

Objective The study on the population dynamics of striped hamster provided the basis for prediction and control.Methods The population dynamics of striped hamster( Cricetulus barabensis) was investigated by rectilinear-trapping method in the middle ten days of each month from April to October from 1991 to 1998 on Ordos sandland.Results All the specimens were divided into five age groups based on their body weight excluding viscera.There are seasonal and annual changes in population number of striped hamster.The sex ratio was 58.29% of all the specimens and the male accounted for a larger proportion than the females.The beginning breeding period of the females was the same with years.The stopping beeding priod of the females varied every years.An annual average liller size of female was 5.77±0.16 in 1991-1998.An annual average pregnant rate was 25.93%.

Objective:Study on the diovision of age group and composition of population of desert hamster.Methods:A total number of 2161 specimen were collected,among which 1089 were males and 1072females.With the body excluding viscera the speciemens were divided into four age groups.Result:The standards of these age groups were listed below:GroupⅠJuvenile:The body weight excluding viscera was ≤7.0g.GroupⅡSubadult:The body weight excluding viscera was 7.1-9.0g.Group Ⅲ Adult(I):The body weight excluding viscera was 9.1-12.0g.Group Ⅳ Adult(2):The body weight excluding viscera was≥12.1g.Conclusion:The population age composition of desert hamster was seasonal changes.

The studies were carried out on Zhengxiangbai County steppe of Inner Mongoliaduring 1987- 1996.There are seven species of rodents on the grassland.The dominant species isbrandt's vole ( Microtus brandti) which is a kind of social rodent and its population dynamics has awide amplitude.Its population density reached the highest level (mean capture rate was 55%) in1987,but decreased rapidly in 1988 and 1989.The capture rate of 1987 was 36.6 times as much asthat of 1989.The brandt's vole population number underwent a cycle of "steady-increase-peakdecrease- steady" during the ten years.Its damage to pasture taked place on the stages of"increase","peak" and the first year of "decrease".On the contrary,the other rodent species had anarrow amplitude of population number and have never damaged the pasture during the ten years.According to the rodent community composition and populaton dynamics,sustained control measures of rodent pests was putforward in this paper.

Rodent pests were controlled in the same experimental site in Xilinguole natural steppe using warfarin (0.05%) in April to May 1987-1988. The area controlled was 800 ha. each year.In contrast site, mean capture rate of total species in 1987 was 57.49±1.58%, and the numbers of Microtus brandti accounted for 95.59%. The rodent community was Microtus brandti+Phodopus sungorus+Citellus douricus+Allactaga sibirica+Cricetulus barabensis. The mean capture rate of total species in 1988 was 21.31±1.09% and the numbers of M. brandti accounted for 94.87%. The rodent community was the same as in 1987. The mean capture rate of total species in 1989 decreased and it was 14.56±0.78%. The community became P. sungorus+C. barabensis+A. sibirica+Meriones unguiculatus+M. brandti.In contraolledt site, the dominant species was M. brandti and it accounted for 92.00% before controlling in 1987. The community composition was the same as in contrast site at this time. After controlled by chemical rodenticide in May the total capture rate was 0.76%. The numbers of M. brandti decreased, while the numbers of P. sungorus increased and it accounted for 50.00%. The Community became P. sungorus+M. brandti+A.sibirica+Ochotona daurica.As a result, we conclude that control using chemical rodentieide can cause stteeession of rodent community and the process is the same as natural succession.