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Two cricetids and three arvicolines are added to the Fiene local fauna (Irvingtonian) of north-central Kansas. Cricetids include the harvest mouse, Reithrodontomys moorei and grasshopper mouse, Onychomys sp. Arvicolines include the muskrat, Ondatra annectens, red-backed vole, Myodes gapperi, and bog lemming, Mictomys kansasensis. The latter two; taxa are extralimital and indicate cooler and wetter summers than at present in the area. Likewise, the record of Myodes represents the earliest occurrence of the taxon on the central Plains. The rarity of Onychomys relative to the previously reported abundant microtids in the Fiene local fauna indicates that the transition from a granivorous diet in the Blancan to a primarily insectivorous diet it has today was completed during Irvingtonian II.

Concerns over climate change and finite fossil fuels have generated interest in biofuels. Switchgrass (Panicum virgatum), a biofuel feedstock, was planted in intensively managed loblolly pine (Pinus taeda) stands to investigate sustainability of this system for producing an alternative energy source. We hypothesized that changes in understory habitat conditions caused by intercropping switchgrass in pine stands would affect rodent population and community dynamics within three years. Therefore, we assessed effects of three treatments (control pine, switchgrass intercropped in pine, and switchgrass monocrop) on rodent population (abundance, survival, and recruitment) and community (diversity, richness, evenness, and community assemblages) measures. We conducted vegetation surveys and live-trapping during 2013–2015 summers in Kemper County, Mississippi, USA. We conducted 6 trapping sessions each summer (n = 14,112 trap nights per year) and captured 1,733 cotton rats (Sigmodon hispidus), 102 Oryzomys palustris, 31 Mus musculus, 28 Reithrodontomys fulvescens, 22 Reithrodontomys humulis, 20 Peromyscus leucopus, 9 Microtus pinetorum, 9 Peromyscus gossypinus, and 2 Neotoma floridana. We found greater cotton rat abundance and lower recruitment in monocrop versus control plots. Rodent diversity was lower in monocrop than control plots. Intercropped plots had intermediate levels of cotton rat abundance and recruitment, and rodent diversity. More dispersal may have occurred in monocrop plots because of high population abundance and limited habitat availability. Cotton rat survival and rodent community assemblage were similar among treatments but differed among years. Although rodents responded negatively to monocrop plots, our results suggested intercropped plots would be an appropriate management practice in pine plantations to produce biofuel feedstocks while maintaining rodent diversity.

The Cudahy “Fauna” was named by C.W. Hibbard for a fossil assemblage recovered from silty clays beneath the “Pearlette” volcanic ash at the type Cudahy ash pit and other sites in Meade County, Kansas. The “Pearlette” ash comprises several variously dated Yellowstone ashes. The Cudahy (=Lava Creek B) ash is most recently dated at 0.639 ± 0.002 Ma and is an important geochronologic marker in the Great Plains. The term Cudahy Ash Pit local fauna is now used for that of the type locality, although other Cudahy-type (Cudahyan) local faunas have been described. From 1968 to 1971, 30 tons of silty clay and diatomite were collected from below outcrops of Lava Creek B ash at elevations of 988–1058 m (3240–3470 ft) in the High Plains of the Texas Panhandle. Screenwashing yielded about 30 mammal taxa and numerous small amphibians, reptiles, birds, and mollusks. Four local faunas (Woody Draw, Bull Draw, Deadman's Creek, and Mayfield Ranch) are recognized. These faunas, dominated by shrews and microtine (arvicoline) rodents, are compositionally similar to each other and to the Cudahy and Sunbrite ash pit local faunas of Meade County even though the Panhandle sites are 300–340 km (186–211 miles) southwest of the Kansas sites and are 213–280 m (700–920 ft) higher in elevation. The Panhandle faunas contain two new species of Sorex as well as Sorex cf. cinereus, Sorex cudahyensis, Sorex lacustris, Sorex ( Microsorex ) pratensis, Sorex megapalustris, Blarina, Cynomys, Spermophilus, Geomys tobinensis, Thomomys cf. talpoides, Peromyscus cragini, Reithrodontomys moorei, Ondatra annectens, Mictomys meltoni, Microtus llanensis (rare), Microtus paroperarius, and Microtus meadensis. The large sample size of the latter two taxa permits statistical comparisons of teeth with those from Kansas. The Texas faunas further substantiate the Cudahyan as a subage of the Irvingtonian between the older Sappan and younger Sheridanian subages and equivalent to Irvingtonian II based on microtine (arvicoline) rodents. Local habitats consisted of ponds or playas with marshy areas suitable for shrews, muskrats, and bog lemmings. Moist grassy meadows nearby would have been inhabited by voles, mice, and some of the shrews; the less abundant gophers, ground squirrels, and prairie dog would have preferred drier, grassy uplands with well-drained soils. Several mammals (e.g. bog lemming) show affinities with extant boreal species that range through Canada and the northern United States The collective evidence suggests that the Texas Panhandle enjoyed cooler summers with more effective rainfall during Cudahy time.

We estimated phylogenetic relationships among 16 species of harvest mice using sequences from the mitochondrial cytochrome b (cyt b) gene. Gene phylogenies constructed using maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) optimality criteria were largely congruent and arranged taxa into two groups corresponding to the two recognized subgenera (Aporodon and Reithrodontomys). All analyses also recovered R. mexicanus and R. microdon as polyphyletic, although greater resolution was obtained using ML and BI approaches. Within R. mexicanus, three clades were identiWed with high nodal support (MP and ML bootstrap, Bremer decay and Bayesian posterior probabilities). One represented a subspecies of R. mexicanus from Costa Rica (R. m. cherrii) and a second was distributed in the Sierra Madre Oriental of Mexico. The third R. mexicanus clade consisted of mice from southern Mexico southward to South America. Polyphyly between the two moieties of R. microdon corresponded to the Isthmus of Tehuantepec in southern Mexico. Populations of R. microdon microdon to the east of the isthmus (Chiapas, Mexico) grouped with R. tenuirostris, whereas samples of R. m. albilabris to the west in Oaxaca, Mexico, formed a clade with R. bakeri. Within the subgenus Reithrodontomys, all analyses recovered R. montanus and R. raviventris as sister taxa, a Wnding consistent with earlier studies based on allozymes and cyt b data. There was also strong support (ML and BI criteria) for a clade consisting of ((R. megalotis, R. zacatecae) (R. sumichrasti)). In addition, cytb gene phylogenies (MP, ML, and BI) recovered R. fulvescens and R. hirsutus (ML and BI) as basal taxa within the subgenus Reithrodontomys. Constraint analyses demonstrated that tree topologies treating the two subgenera (Aporodon and Reithrodontomys) as monophyletic (ML criterion) was signiWcantly better (p > 0.036) and supported polyphyly of R. mexicanus (both ML and MP criteria – p > 0.013) and R. microdon (MP criterion only for certain topologies; p > 0.02). Although several species-level taxa were identiWed based on multiple, independent data sets, we recommended a conservative approach which will involve thorough analyses of museum specimens including material from type localities together with additional sampling and data from multiple, nuclear gene markers.  2005 Elsevier Inc. All rights reserved.

We compared the initial effects of four forest regeneration treatments (single-tree selection, group selection, shelterwood, and clearcut), and unharvested controls (mature, second-growth forest) on relative abundance of small mammals and small-mammal habitat throughout the Ouachita Mountains of western Arkansas and eastern Oklahoma. We compared small-mammal capture rates in 20 forest stands (4 replicates of 5 treatments) for 2 years prior to harvest treatments, and 1.5, 3.5, and 5.5 years after treatment. We also examined relationships among small mammals, treatments, and habitat conditions. Before harvest, all stands where characterized by high basal areas (BA), little understory vegetation, and low small-mammal capture rates. Compared with pre-harvest numbers, the number of individuals captured increased nearly five-fold in treated stands 1.5 years after harvest. After harvest, capture rates for all taxa combined were significantly greater in harvested stands (regardless of treatment) than in unharvested controls. Fulvous harvest mice (Reithrodontomys fulvescens) capture rates were greatest in clearcuts. Fulvous harvest mice, cotton rats (Sigmondon hispidus), and pine voles (Microtus pinetorum) were associated with abundant herbaceous vegetation in the understory and low BA. Eastern woodrats (Neotoma floridana), golden mice (Ochrotomys nuttalli), and Peromyscus spp. were associated with moderate to dense woody vegetation in the understory and intermediate BA levels. No taxon of terrestrial small mammal was captured exclusively in unharvested stands; most taxa we captured appear to be either disturbance-adapted or tolerant to disturbances from timber harvest.

Loblolly pine ( Pinus taeda L.) regeneration or establishment impacts a large area over the southern US but few studies have examined the microhabitat relationship of small mammals on young pine stands. We collected over 1600 small mammals on natural and artificial loblolly pine regeneration areas. Twenty-five habitat variables describing cover, forage, and structure were measured or derived at each trap station. We used discriminant function analysis (DFA) to construct microhabitat utilization models for the six most abundant small mammal species common to young loblolly pine regeneration areas including the southern short-tailed shrew ( Blarina carolinensis ), golden mouse ( Ochrotomys nuttalli ), white-footed mouse ( Peromyscus leucopus ), cotton mouse ( P. gossypinus ), harvest mouse ( Reithrodontomys humulis ), and cotton rat ( Sigmodon hispidus ). We compared vegetation characteristics at stations where each species was captured versus stations where it was not captured. Models of species microhabitat associations helped explain observed differences in species succession and abundance. Coarse woody debris (i.e. logs and stumps) was found to be an important microhabitat component for O. nuttalli . Logs and stumps were important to P. gossypinus , P. leucopus and S. hispidus . Shrew capture stations had a significantly taller canopy and significantly greater biomass of vines than did non-shrew captures sites. Golden mouse capture stations had significantly longer logs, shorter distance to nearest log, and lower herbaceous profile diversity. Distance to nearest tree was significantly greater while tree height and vine cover were significantly lower at white-footed mouse capture stations. Cotton mouse microhabitat variables describing woody biomass were greater and stump size, tree height and distance to logs were significantly lower at capture stations. Harvest mice capture stations were characterized as having significantly lower tree height than non-capture stations. Cotton rat microhabitat was characterized by twelve variables but cotton rats were collected almost exclusively on the youngest stands with the greatest grass and herbaceous structure. Numerous variables play an important role in determining habitat quality for the array of small mammal species commonly found in early successional pine habitats in the southeast. Microhabitat models help to explain some of the patterns of species occurrence and succession. While the methods used in this study do not necessarily demonstrate preferred habitat, our results allow identification of areas of use.

Hantaviruses, family Bunyaviridae, are rodent-borne RNA viruses that can cause hantavirus pulmonary syndrome (HPS) in various regions of the Americas. A coevolutionary relationship exists between hantaviruses and their specific rodent reservoir hosts; the phylogeny of the viruses generally matches that of the rodents. There are several Peromyscus -borne hantaviruses, including Sin Nombre virus, the most common cause of HPS in North America. This report describes the genetic detection and characterization of a newly discovered Peromyscus boylii -borne virus, Limestone Canyon (LSC) virus, the most divergent member of the Peromyscus -borne hantaviruses to date. Analysis of a 1209-nucleotide region of the S segment of LSC virus showed it to be more closely related to hantaviruses found in harvest mice ( Reithrodontomys megalotis and R. mexicanus ) than to other Peromyscus -associated hantaviruses (Sin Nombre, New York, and Monongahela). Phylogenetic analysis of virtually the entire M genome segment (3489 nucleotides) of LSC virus revealed a similar picture in which LSC virus was found to be very distinct from other Peromyscus -associated viruses, but its exact relationship to the other Peromyscus -borne and the Reithrodontomys -borne viruses was not resolved. These results indicate that hantavirus host species-jumping events can occur by which a hantavirus may switch to, and become established in, a rodent host belonging to a different genus. P. boylii are present throughout the southwestern United States and central Mexico. More extensive screening of HPS patients by using RT–PCR assays will be necessary to determine if LSC virus can cause human disease.

We recently described a novel hantavirus (HMV-1) of the western harvest mouse Reithrodontomys megalotis. Screening of 181 additional specimens of Reithrodontomys from the United States and Mexico, including samples of R. mexicanus, R. sumichrasti, and R. gracilis of Costa Rica, for antibodies to hantavirus nucleocapsid protein revealed a widespread enzootic of hentavirus infection. Genetic analyses of 7 S genomes of Reithrodontomys -associated hantaviruses demonstrated that the enzootic of HMV-1 extends from central Mexico into the southwestern United States. A presumed deer mouse hantavirus was found in an R. megalotis animal in Mexico. A highly divergent HMV-1-like virus, tentatively called HMV-2, was identified in a Costa Rican R. mexicanus. These data suggest a longstanding radiation of hantaviruses among New World harvest mice. We identify possible opportunities for genetic exchange among hantaviruses of related rodent hosts.

1. 1. The activity of l -gulonolactone oxidase (EC 1.1.3.8) in livers of 49 species of eutherian mammals varied intraspecifically among individuals; coefficients of variation were 0.2 to 0.4 in many species. 2. 2. Differences observed in l -gulonolactone oxidase activity among strains of laboratory rats and domestic rabbits are probably genetically controlled. 3. 3. Pronounced sex differences in l -gulonolactone oxidase activity were found in some species, particularly in the genera Peromyscus, Reithrodontomys and Onychomys. 4. 4. Mormota monax exhibited seasonal variation in l -gulonolactone oxidase somewhat like that previously observed in Sylvilagus floridanus; no such seasonal variation was found in Sciurus carolinensis. 5. 5. Hibernation did not affect l -gulonolactone oxidase activity in Spermophilus tridecemlineatus. 6. 6. In four species of rodents, Microtus ochrogaster, Tylomys panamensis, Octodon degus and Sigmodon hispidus, l -gulonolactone oxidase activity was not affected by the level of dietary ascorbate.

1. 1. Among cricetids there appears to be a direct relationship between the percentage medullary thickness and the ability to concentrate urine, at least congenerically. 2. 2. A correlation was established between a renal index and the rainfall within the geographic range of each taxon. 3. 3. A pattern was found relating renal structure to the speculated relative moisture availability among environmental associates within specific geographic areas.