Rodent Species Composition Research Articles

Population and Species Composition of Rodents and Insectivores in Settlements of the West Kazakhstan Region Located in the Plague Enzootic Territory

The aim of the study was to analyze the abundance, species composition, dissemination of mouse-like rodents and other small mammals in the settlements of the West Kazakhstan Region over the past 6 years and the factors contributing to the change in the numbers in the long-term aspect.Materials and methods. We utilized the data obtained by employees of the Uralsk Plague Control Station, affiliated branch of the Republican State Enterprise “National Scientific Center of Particularly Dangerous Infections named after Masgut Aikimbaev” during a scheduled epizootiological survey of plague foci located in the West Kazakhstan Region.Results and discussion. The average annual number of rodents and insectivores in the settlements on the plague-enzootic territory of the West Kazakhstan Region was 5.1 in spring season, 8.1 in autumn, with 30.0 % occupancy of the facilities. In outbuildings, the number of rodents was three times higher than in residential buildings and amounted to 11.5 (residential buildings – 3.7). The general species composition of small mammals caught in the settlements was represented by seven species, among which the house mouse was a predominant one (97.5 %). The second place was occupied by the small shrew (1.7 %). There is a downward trend in the number of rodents in the steppe foci of plague (over 18 years – an average of 22.0 %). A slight increase in the number of animals by 2.0 % has been registered in the sandy focus.

Small mammal abundance and diversity along an altitudinal gradient in the Simien Mountains National Park, Ethiopia

Abstract Species richness, abundance, diversity, and distribution of rodents and shrews along altitudinal gradients in the Simien mountains national park, Ethiopia, were studied using Sherman traps. Rodents and shrews were trapped at four altitudinal ranges (2,800 m a.s.l., 3,200 m a.s.l., 3,600 m a.s.l. and 4,000 m a.sl.). A total of 202 individuals were captured, comprising 184 rodents and 18 shrews. In total, there were eight species of rodents and one shrew species. The relative abundances of Lophuromys simensis and Stenocephalemys albipes were the highest in the early dry season, dry season, and wet season. The relative abundances of Desmomys harringitoni (7.43%), Dendromys lovati (4.46%), and Mus imberbis (1.98%) were the lowest across the study area. The highest species diversity was recorded at an altitude of 2,800 m a.s.l. (H’ = 1.82). Species composition of rodents and shrews found at altitudes of 2,800 m a.s.l. and 3,200 m a.s.l. were highly similar (Sij = 0.97363). In contrast, the least similar species composition was between altitudes of 2,800 m a.s.l. and 4,000 m a.s.l. (Sij = 0.15632). The abundance, distribution, and diversity of rodents and shrews were significantly correlated with altitude (p = 0.000). Species abundance, distribution, and diversity in the Simien Mountains National Park were significantly correlated with altitude (0.377) and habitat types (0.306). Species composition of small mammals varied among altitudes, seasons, and habitat types, with six rodents and one shrew species being endemic. Notably, the park is subjected to various environmental disturbances, such as fires, grazing, and agriculture, which can negatively impact these small mammals, particularly the endemic species.

Incidence of Orthohantavirus infection in humans follows observed changes in rodent reservoirs, Hubei Province, China (1984-2010).

Orthohantaviruses (genus Orthohantavirus, family Hantaviridae of order Bunyavirales) are rodent-borne viruses causing 2 human diseases: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS), which are mainly prevalent in Eurasia and the Americas, respectively. We initiated this study to investigate and analyze the Orthohantaviruses infection in rodent reservoirs and humans in the Hubei Province of China from 1984 to 2010. The study included 10,314 mouse and 43,753 human serum samples. In this study, we analyzed the incidence of Orthohantavirus infection in humans and observed changes in rodent reservoirs in Hubei Province. The results indicated that although the incidence of HFRS declined from the 1990s, the human inapparent infection did not decrease dramatically. Although elements of the disease ecology have changed over the study period, Apodemus agrarius and Rattus norvegicus remain the major species and a constituent ratio of Rattus norvegicus increased. Rodent population density fluctuated between 16.65% and 2.14%, and decreased quinquennially, showing an obvious downward trend in recent years. The average orthohantaviruses-carrying rate was 6.36%, of which the lowest rate was 2.92% from 2006 to 2010. The analysis of rodent species composition showed that Rattus norvegicus and Apodemus agrarius were the dominant species over time (68.6% [1984 to 1987] and 90.4% [2000 to 2011]), while the composition and variety of other species decreased. The density of rodents was closely related to the incidence of HFRS (r = 0.910, P = .032). Our long-term investigation demonstrated that the occurrence of HFRS is closely related to rodent demographic patterns. Therefore, rodent monitoring and rodent control measures for prevention against HFRS in Hubei are warranted.

Species Composition of Rodents at Padang Chong Forest Reserve, Perak

There are at least four families of rodents identified in Peninsular Malaysia namely Muridae, Sciuridae, Hystricidae, and Rhyzomidae. Although rodents are widespread throughout Peninsular Malaysia, information on rodents at Padang Chong Forest Reserve (PCFR) is scarce. Therefore, the main objective of this study is to identify and document the species composition of rodents at PCFR. Samplings were carried out at two plots along the gradient from the border of PCFR namely Plot 1 (500m) and Plot 2 (1km). The size of the respective plot is 1ha with 10 transect lines (AJ), 100m in length separately. These plots were sampled for five times from June to November 2022. Based on this study, a total of 65 individuals from nine species of rodent were documented. These nine species were identified from two families namely, Muridae (5 spp) and Sciuridae (4 spp). Of these, Leopoldamys sabanus was recorded as the highest captured species (25 individuals), followed by Maxomys whiteheadi (19 individuals) and Callosciurus notatus (7 individuals). There is no significant difference in terms of species composition between these plots, Plot 1 (n=33) and Plot 2 (n=32), which further supported by t-test value result (t-test=0.928; p(value)> 0.05). However, there is a single representative of Sundamys muelleri captured in Plot 1 which prefers the riverine area (around 10m). Callosciurus notatus were captured most in Plot 2 (6 individuals) compared to Plot 1 (1 individual). Certain areas nearby to Plot 2 were opened for agricultural purposes which explained the existence of this species at Plot 2. From this information, it is hoped that further actions can be taken to conserve the area to ensure the small mammal communities are preserved.

An inventory of the types of rodent spread in Houses with a study of external parasites of the most dominant species at Esna area, Luxor Governorate, Egypt

An inventory of the types of rodent spread in Houses with a study of external parasites of the most dominant species at Esna area, Luxor Governorate, Egypt

Assessing scrub typhus and rickettsioses transmission risks in the Chiang Rai province of northern Thailand

BackgroundScrub typhus is an important disease in the Asia-Pacific countries with increasing relevance for public health worldwide. Entomological risk assessment for scrub typhus and rickettsial disease in Phu Chi Fah village-Chiang Rai was performed to determine areas at greatest risk for disease transmission in order to increase awareness of diseases to travelers and healthcare workers. MethodsFrom 2016 to 2018, rodents and chiggers were collected from 7 sites covering residential, grassland, and forest areas to determine the prevalence of pathogen of interest. The correlation between land type and vector-host-pathogen interaction system was investigated. ResultHigh prevalence of O. tsutsugamushi-infected and Rickettsia-infected chiggers was observed especially in areas with grassland and forest ecotones. Chigger and rodent species composition were negatively associated with the level of human disturbance. Increased density of rodents was responsible for a higher abundance of chigger population and increased prevalence of O. tsutsugmaushi infection in chigger in the following year. ConclusionCommunities in the study areas have an increased exposure risk to scrub typhus and potentially spotted fever group rickettsiosis. Travellers to this endemic area should pay more attention pathogen risks so as to avoid vector and disease exposure. Seasonal rodenticidal activity may help migitate the risk of pathogen transmission.

A Population-Based Approach to Determining the Borders and Number of Natural Plague Foci

A population-based approach to determining the borders and number of natural plague foci implies that the specialists in the field accept the concept that the existence of a natural plague focus is always provided by a single population of the main carrier. The discussion of this approach was motivated by the data collected in the course of a long-term study of the Hissar natural plague focus in Tajikistan. It was demonstrated that the area of this focus constitutes only 300 km2, and its functioning is maintained by a single relatively small population of Microtus carruthersi Thomas, 1909, the main plague carrier. The Hissar mountain range territories neighboring the focus have been surveyed for plague for more than 20 years. However, the plague pathogen (Yersinia pestis Lehmann, Neuman, 1986) could not be detected notwithstanding the absolute identity of the species composition of rodents and fleas. Many known natural plague foci are considerably larger in size than the Hissar focus and are inhabited by several populations of the main carrier. For example, five groups of populations of the common vole (Microtus arvalis Pallas, 1778), the main plague carrier, are described in the Eastern Caucasus high mountain focus occupying an area of 23 500 km2. In the Tuva mountain focus, the plague pathogen was found in six populations of the main carrier, the long-tailed ground squirrel (Spermophilus undulatus Pallas, 1778). On the territory of the Muyunkum desert natural plague focus occupying an area of 93 000 km2, 17 populations of the great gerbil (Rhombomys opimus Lichtenstein, 1823), the main plague carrier, are distinguished. Similar data are available for a number of other foci. Significantly, in different populations of the main carriers, the differences in the genotypes of both rodents and the plague pathogen were described, and asynchrony in plague epizootics could be traced. In such a way, the plague parasitic cenosis functioning within the borders and the habitation areal of a single population of the main carrier constitutes an autonomous standalone natural focus. Hence, the foci occupied by several populations of the main carrier are, in fact, groups of autonomous foci with a similar biocenotic structure. Therefore, a considerably larger number of natural (autonomous) foci are present within the plague natural focality zones than is commonly assumed.

Rodent species composition, relative abundance, and habitat association in the Mabira Central Forest Reserve, Uganda

A study was conducted in Mabira Central Forest Reserve in Uganda to determine rodent species composition, relative abundance, and habitat association. A total of 1,030 rodents belonging to 14 species were captured on 10,584 trap nights. Rodent species recorded include: Lophuromys stanleyi, Hylomyscus stella, Praomys jacksoni, Mastomys natalensis, Lophuromys ansorgei, Lemniscomys striatus, Aethomys hindei, Mus triton, Mus minutoides, Deomys ferrugineus, Gerbilliscus kempi, Rattus rattus, Grammomys kuru, and Hybomys univittatus. Overall, L. stanleyi (23.7%) was the most dominant species followed by H. stella, P. jacksoni, and M. natalensis. Species richness and evenness was highest in the regenerating forest habitat and least in the intact forest habitat. Rodent abundance was significantly affected by habitat type. The regenerating forest habitat had the highest number of animals, while the lowest numbers were observed in the depleted forest habitat. Species diversity was higher in regenerating forest habitat and lowest in the intact forest. The three habitats appeared distinct in terms of rodent species composition and there was a strong association between the two trapping grids in the same habitat type. All ordination plots showed that different rodent species consistently associated with distinct habitats. Habitat type and seasonal changes influenced rodent composition, relative abundance and habitat association. Composition of rodent community reflected the level of habitat degradation and can be used as a proxy for evaluating the biodiversity of lowland tropical forests.

Population Approach to Determination of the Borders and Number of Natural Plague Foci

Population approach to determination of the borders and number of natural plague foci implies the specialists’ acceptance of the concept that the existence of a natural plague focus is always provided by a single population of the main carrier. Motivation for our discussion of such an approach was the data of a long-term study of the Hissar natural plague focus (Tadzhikistan). The area of the focus was only 300 km2 and its functioning was maintained by a single, relatively small population of Microtus carruthersi (Thomas, 1909) – the main carrier of plague. The Hissar mountain range territories adjacent to the focus have been surveyed for plague for more than 20 years, however, no plague agent (Yersinia pestis Lehmann, Neuman 1986) has been found, despite the complete identity of the species composition of rodents and fleas. Many of the known natural plague foci are significantly larger in size than the Hissar focus and inhabited by several populations of the main carrier. For instance, in the East-Caucasian high-mountain focus, covering the area of 23,500 km2 , five groups of common vole populations (the main carrier of plague) are distinguished (Microtus arvalis Pallas, 1778). In the Tuva mountain focus, the plague agent was detected in six populations of the main carrier – the long-tailed souslik (Spermophilus undulates Pallas, 1778). In the territory of the Mojynkumsky desert natural plague focus that occupies 93,000 km2 , 17 populations of the great gerbil (Rhombomus opimus Lichtenstein, 1823) were singled out. Similar data are available for a number of other foci. Revealingly, in different populations of the main carriers, genotype differences were identified, both in rodents and the plague agent, as well as asynchrony in the plague epizooty development. Thus, the plague parasitic coenosis, operating within the boundaries and in the territory of a single population of the main carrier, constitutes an autonomous, standalone natural focus. Therefore, the foci with several populations of the main carrier are, in fact, groups of autonomous foci with a close, similar biocoenotic structure. There are many more natural (autonomous) foci within the natural plague focality zone than is widely assumed.

Palaeoenvironments of the Manych Valley at the End of Late Pleistocene Based on Rodent and Mollusk Data from Sanmanych (Rostov District, Russia)

A thorough consideration is given to the geological, palaeotheriological and malacological materials obtained from the Pleistocene Sanmanych locality, which is the only locality with mammal fauna in the Manych depression (46°24′53″ N, 42°36′25″ E). The brackish-water mollusk composition indicated that the bone-bearing series should be correlated to the Early Khvalynian transgression. The fossil record gives an insight into the palaeoenvironment at the time that the Caspian Sea water broke through the Manych depression into the Black Sea basin. The faunal evidence points to arid conditions and a cool climate. The rodent species composition is rather poor; it exclusively includes species indicative for an open environment, which suggests a wide spread occurrence of steppe and semi-deserts in the Manych valley during the Late Glacial (~16–12 ka BP).

Small mammals in cornfields and associated peripheral habitats in central Nebraska

In the Great Plains, many native grasslands have been converted to agricultural fields during the last two centuries. Peripheral habitats along edges of crop fields generally consist of linear habitats along roads, with many of these habitats used by native fauna. Our study examined capture rates and species composition of small mammals in cornfields, herbaceous roadside ditches, and wooded shelterbelts in central Nebraska. We captured nine species of small mammals. The Prairie Vole (Microtus ochrogaster) and Western Harvest Mouse (Reithrodontomys megalotis) were captured almost exclusively in roadside ditches, the White-footed Deermouse (Peromyscus leucopus) was captured most often in wooded shelterbelts, and the North American Deermouse (Peromyscus maniculatus) was common to abundant in all three habitats. Capture rates of small mammals were greatest in roadside ditches and least in cornfields. Herbaceous roadside ditches contained the greatest species richness with seven species, whereas shelterbelts and cornfields each had five species. Species composition of rodents differed in shelterbelts comprised solely of eastern red-cedars (Juniperus virginiana) compared to those with a mixture deciduous and coniferous trees. Our study demonstrated that roadside ditches associated with agricultural fields serve as habitats for many prairie species whereas wooded shelterbelts along agricultural fields support both woodland and prairie species in central Nebraska. Cornfields mainly were inhabited by North American Deermice but did not support many other species of small mammals. Although agricultural practices have reduced the quantity of grasslands for prairie species across the region, habitats associated with periphery of fields appear to serve as alternative habitats for small mammals throughout the Great Plains.

Bush encroachment influences nocturnal rodent community and behaviour in a semi-arid grassland in Gujarat, India

Bush encroachment is one of the major threats to grasslands globally. The increased cover due to bush encroachment can strongly influence the behaviour of animals adapted to a more open habitat. In this study, we explored the effects of bush encroachment on the foraging behaviour of nocturnal rodents the semi-arid Banni grasslands of western India, once one of India's largest tropical grassland habitats. We quantified foraging behaviour using the giving-up density (GUD) framework, across two sites that differed in the extent of bush encroachment. Rodents in the site with high bush encroachment (the dense site) exhibited higher foraging costs (higher GUD) in early summer compared to the site with low bush encroachment (the sparse site). Rodents in the dense site also had lower activity. The dense site supported higher richness and relative abundance of generalist rodents than the sparse site. Our results suggest that bush encroachment may be associated with higher foraging costs for nocturnal rodents and result in a change in species composition of rodents. Given the ecosystem engineering services performed by native grassland species, these results can have negative implications for grassland restoration.

Rodent, snake and raptor use of restored native perennial grasslands is lower than use of unrestored exotic annual grasslands

Abstract In California's Central Valley, most native grasslands have been destroyed or degraded due to invasion, farming and development. Grassland restoration is often assumed to provide improved wildlife habitat, ostensibly increasing the abundance and diversity of at least some native wildlife species relative to unrestored, invaded annual grasslands. We compared rodent, snake and raptor activity and species richness at paired unrestored and restored grasslands across four blocked locations in the Central Valley using trapping and observational surveys in up to four seasons per guild from 2014 to 2015. Restored treatments were planted with native perennial grasses 13–24 years prior to study initiation but were partially re‐invaded by Mediterranean annual grasses and forbs. Unrestored treatments contained similar non‐native plant species assemblages as restored treatments, but did not contain any native grass. Rodent, snake and raptor activity was generally higher in unrestored relative to restored treatments. For rodents, the non‐native Mus musculus (house mouse) showed the greatest disparity in abundance, while greater raptors and snakes likely responded to greater rodent abundance. Within treatments, species‐specific rodent responses were related to structure of physical vegetation. In particular, Peromyscus maniculatus (native deer mouse) was associated with more bare ground and shorter vegetation, while the house mouse was associated with less bare ground and taller vegetation, regardless of treatment type. Substantial changes in rodent species composition were observed over short periods of time (<3 months) after unplanned manipulation of vegetation structure via livestock grazing, with patterns reflecting the species‐specific response to physical vegetation structure. Synthesis and applications. Our results reveal that while grassland restoration may promote persistence of native plant communities, restoration may not be beneficial to some higher trophic levels, and in fact may reduce habitat value for some native predators in grasslands invaded by Mediterranean plant species. Changes in vegetation structure can strongly impact wildlife species composition, suggesting a more nuanced approach is required for the restoration of desired wildlife communities. Thus, species‐specific goals should be carefully considered to ensure improved alignment of restoration methods with expected restoration outcomes.

Rodent Fauna of the Middle Paleolithic Cave Site Taglar (Transcaucasus): Paleoecology and Environment

Rodent fauna from the well-known cave site Taglar (Middle Paleolithic), located in Karabakh (Transcaucasus) is described. The species composition includes Allactaga williamsi, Meriones libycus, Cricetulus migratorius Ellobius lutescens, Arvicola terrestris and Microtus (Microtus) obscurus. Some archaic characters in water vole teeth morphology were revealed. Data of cave site Taglar are compared with rodent fauna of unique Mousterian cave site Azych (Transcaucasus). The ecological features of rodent fauna refl ect the predominance of arid steppe-like and even semidesert-like landscapes near the site. The fauna most probably corresponds to the megainterstadial of the last glaciation (MIS 3). The new data elucidate species composition of rodents of Transcaucasus during the warm stage of last glaciations and the environments surrounding this unique Mousterian cave site of ancient humans.

Bottom-up regulation of desert grassland and shrubland rodent communities: implications of species-specific reproductive potentials

Abstract We conducted an 11-year comparative study on temporal variation in rodent density, biomass, and species composition dynamics from adjacent grassland and shrubland environments in the Chihuahuan Desert of North America, in relation to rainfall and plant production. We found that rodent assemblages from those environments were only 14% similar in overall species composition, but consisted of different species in the same genera with similar ecological attributes. Each rodent community was numerically dominated by a different species of granivorous kangaroo rat, and the 2 rodent communities paralleled each other in body sizes and trophic structure. Rodent species compositions changed little over the 11-year period, despite considerable variation in rodent densities and biomass and in rainfall and plant production. Rodent abundance and biomass from both communities increased in relation to temporally variable rainfall and plant production, especially resulting from a series of El Nino and La Nina Sou...

Are the closed landfills recovered habitats for small rodents? A case study in a riparian site, Buenos Aires, Argentina

The establishment of landfills in urban areas leads to extensive disturbances. Their development after landfill closure depends on the characteristics of the soil cover, the surrounding communities and the dispersal of plants and animals. This study was carried out in a landfill closed in 2004, surrounded by an urban area, freshwater marshes and a riparian forest. The aim of this study was to determine the role that the closed landfill may play in maintaining rodent communities typical of this zone and its relation to characteristics of the sites. Four rodent and plant samplings were carried out from December 2005 to September 2006 at five sites inside the landfill: three filled cells and two areas of the riparian margin. We recorded a total of 433 individual rodents. The rodent community of the closed landfill included species typical of rural, riparian and rural habitats: Akodon azarae (358), Oligoryzomys flavescens (32), Deltamys kempi (14), Rattus rattus (14), Cavia aperea (11) and Scapteromys aquaticus (4). Rodent species composition varied among sites, but A. azarae was usually the dominant species. We found a rich rodent community mostly composed of wild species. The relictual riparian margin may have served as a major refuge for native rodent community while the landfill was in operation, and after closure it possibly acted as a source for some species to colonize the covered cells.

Rodent and Flea Abundance Fail to Predict a Plague Epizootic in Black-Tailed Prairie Dogs

Small rodents are purported to be enzootic hosts of Yersinia pestis and may serve as sources of infection to prairie dogs or other epizootic hosts by direct or flea-mediated transmission. Recent research has shown that small rodent species composition and small rodent flea assemblages are influenced by the presence of prairie dogs, with higher relative abundance of both small rodents and fleas at prairie dog colony sites compared to grasslands without prairie dogs. However, it is unclear if increased rodent or flea abundance predisposes prairie dogs to infection with Y. pestis. We tracked rodent and flea occurrence for 3 years at a number of prairie dog colony sites in Boulder County, Colorado, before, during, and after a local plague epizootic to see if high rodent or flea abundance was associated with plague-affected colonies when compared to colonies that escaped infection. We found no difference in preepizootic rodent abundance or flea prevalence or abundance between plague-positive and plague-negative colonies. Further, we saw no significant before-plague/after-plague change in these metrics at either plague-positive or plague-negative sites. We did, however, find that small rodent species assemblages changed in the year following prairie dog die-offs at plague-affected colonies when compared to unaffected colonies. In light of previous research from this system that has shown that landscape features and proximity to recently plagued colonies are significant predictors of plague occurrence in prairie dogs, we suggest that landscape context is more important to local plague occurrence than are characteristics of rodent or flea species assemblages.

Effects of large herbivores on murid rodents in a South African savanna

Abstract:Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to hares) from sixteen 40 × 40-m plots of vegetation by using different fence types. We determined grass species composition and vegetation height and collected capture–mark–recapture data on murid rodents. Nutrient concentrations of the dominant grass species and rodent diet compositions were analysed. We found that herbivore species of different body sizes had different effects on murid rodents. The exclusion of medium-sized herbivores, such as warthog, impala and nyala increased the abundance of high-quality grass species, especiallyPanicum maximum. However, the dominant rodent speciesLemniscomys rosaliapreferred the most abundant grass species, rather than high-quality grasses. The absence of large bulk feeders, such as zebra, buffalo and white rhino led to an increase in vegetation height. In response, tall vegetation promoted both rodent abundance and species diversity and altered rodent species composition. Ultimately, our results indicate that the greatest effect on murid rodents came from the reduction of vegetation cover by large bulk feeders, which likely increased rodent predation risk.

Micro- and Macrohabitat Associations in Mojave Desert Rodent Communities

Characterizing habitat associations of species is fundamental to understanding the mechanistic basis of community organization. Typically, investigators estimate microhabitat characteristics that account for significant amounts of variation in species composition. Nonetheless, highly resolved microhabitat characteristics may account for no more variation in species composition than coarse macrohabitat distinctions, particularly in heterogeneous environments. We describe micro- and macrohabitat associations of 13 species of nocturnal rodents distributed across 31 communities within the Mojave Desert. Rodent species composition, biomass of 81 perennial plant species, representation of 9 soil and rock classes, and the percent cover of annuals and grasses were quantified. Communities also were assigned to macrohabitats based on qualitative characteristics. Multivariate analysis of variance indicated highly significant community-wide differences among macrohabitats and species-specific analyses of variance substantiated differences for all but 1 species analyzed. Microhabitat characteristics accounted for approximately 55% of the variation in rodent species composition. Moreover, microhabitat characteristics accounted for 17% variation in rodent species composition over and beyond that shared with macrohabitat distinctions. Micro- and macrohabitat perspectives provide complimentary insights into species composition of rodent communities. Edaphic features in particular represented important environmental heterogeneity that likely acts both directly on rodent species composition and indirectly through influencing variation in plant species composition. Indeed, the Mojave Desert is represented by a spatial mosaic of species-rich and compositionally dynamic rodent communities that will provide many insights into the coexistence of species at regional spatial scales.

Recovery of a rodent community in an agro‐ecosystem after flooding

AbstractThe Dongting Lake region is one of the areas prone to flood disaster in China. Despite the frequent occurrence of flooding in this area, few studies have analysed its effects on rodent communities, especially their recovery after withdrawal of floodwaters. We carried out a study of rodent recovery after flooding of the Dongting Lake region in 1998. Rodent population monitoring in the flooded countryside of the Dongting Lake region was conducted during 1998–2001. The census was conducted in Anzao polder of Anxian County in Hunan Province, where the dike burst in 1998 and thousands of hectares of farmland were flooded from July to October. The results indicate that flood disaster could provide important changes in rodent community structure. Firstly, species abundance in the post‐flood area became less than in the normal area. Striped field mice Apodemus agrarius colonized the flooded area in farmland until March 2000, and Norway rats Rattus norvegicus and house mice Mus musculus occurred in July and December 2000, respectively. The degree of the effect on the rodent community in residential premises is less than that in farmland. However, the rodent community in the flooded area could recover and become similar to the normal community. The recovery of rodent species composition was faster in residential premises than in farmland after flooding. Secondly, there was a similar tendency of the dominant concentration indices between post‐flood and normal areas. Thirdly, inundation for a long period could reduce the species diversity of the rodent community in farmland. The significant difference in abundance was continued to 2000 in post‐flooded farmland; however, the influence on the rodent community in residential premises was less and their diversity indices did not differ in 1999. Similarity indices indicated that variation between post‐flood and normal areas had been gradually becoming low from 1999 to 2001. Finally, the monitoring data showed that rodent populations in the flooded area were less than those in the normal area in the first step after withdrawal of floodwaters. However, the rodent population increased rapidly in the flooded area, and became greater than that in the unflooded area in half a year. The population in the flooded area also increased faster than that in unflooded neighbouring area after the application of rodenticide. Another phenomenon was that the population density of rodents could reach levels greater than the normal area, and may continue for more than 2 years. Flood disasters could reduce population densities and species abundance, species diversity and evenness, while increasing dominant concentration indices of the rodent community. However, after 3 years, the rodent community structure became similar to that in the non‐flooded area, except for high density. The recovery of rodent communities in residential premises was faster than that in farmland for a lesser degree of flooding.