Habitat selection by small mammals in Brazilian Pampas biome

The use of microhabitats by small mammals was investigated in an area of Pampas in southern Brazil. We used 10 transect lines with 12 live-traps during six fieldwork sessions between June 2009 and April 2010. Sixteen environmental variables measured were summarized by a principal component analysis (PCA). Richness, total abundance and abundance of each species captured were correlated with the first two PCA axes. The environmental variables were also correlated with the small-mammal abundance through a canonical correspondence analysis (CCA). The first axis was related to variables that characterize forest environments, such as canopy cover and number of trees, and the second axis (with which the species richness and abundance were associated) was related to water, arthropods and herbaceous vegetation. The CCA and PCA showed a significant effect of microhabitat variables on species occurrence. In view of the great variability of environments in the study area and the correlation of the species with the environment variables measured, the degree of heterogeneity seemed to be an important factor associated with the small-mammal variation among microhabitats.     

Movements by small mammals on a radioactive waste disposal area in southeastern Idaho

Average linear movement by populations of Dipodomys ordii, Microtus montanus, Perognathus parvus, and Peromyscus maniculatus   was investigated over a 15-month period by live trapping on a low-level, radioactive waste disposal area in Idaho. No significant differences in movement among habitats were observed seasonally, excepting M. montanus in spring. Average linear movements within habitats ranged from 20 to 70 m for all species, but some patterns varied seasonally and among age classes for individual species. Although predation on contaminated small mammals from the disposal area is a vector of radionuclide transport, local movements by these rodents do not appear to be of sufficient magnitude to contribute significantly to redistribution of radioactive particles.     

Habitat characteristics of small mammals in southeastern Utah

We describe habitat characteristics of 8 small mammal species occurring in the Manti-LaSal National Forest in southeastern Utah. Thirty-seven grids across 7 vegetation types were sample by live-trapping from May through October 1994 and 1995. Logistic regression models of habitat measurements correctly classified small mammal presence 36%-87% of the time. Except for 1 instance, 4 Peromyscus species present in a specific vegetation type were negatively associated with forb or grass cover. Microtus montanus was present primarily on mesas and was positively associated with tall tree and low shrub cover. Neotoma mexicana was present only in canyons and was found primarily in the pinyon-juniper ( Pinus edulis-Juniperus osteosperma ) vegetation type. Tamias spp. was present in all vegetation types. Our results allow better management of these species by providing greater understanding of their use of habitat within vegetation types.     

Note on fungi in small mammals from the Nothofagus Forest in Argentina

Fungal spores from the same taxa of fungi that occur in the Pacific Northwest are reported from digestive tracts of31 rodents of 5 genera from the Nothofagus forest of southern Argentina. Mycophagy (fungal feeding) by forest rodents has been well documented in North America (Fogel and Trappe 1978, Maser et al. 1978, Mclntire 1984, and others), Europe (Blaschke and B?umler 1986, Durrieu et al. 1984), and Australia (Malajczuk et al. 1987). The purpose of this note is to report fungi consumed by rodents of the Argentine Andinian Patagonic forest (see Dimitri 1972,McQueen 1977, and Ward 1965 for a discussion of this forest), where mycorrhizal fungi may be an important part of the forest-rodent ecology (Cabrera and Yepes 1960, Pearson 1983, 1948, Pearson and Pearson 1982).     

"Curing" of Nicotiana attenuata leaves by small mammals does not decrease nicotine contents

Basal leaves of Nicotiana attenuata are frequently found neatly excised at the petiole and piled on rocks or soil in the sun until dry, after which they disappear, sometimes to be found again in the nests of Neotoma lepida . In response to herbivore attack, N. attenuata increases the concentration of nicotine in its leaves, where it functions as an induced defense. Since excision of leaves at the petiole allows for leaf removal without substantially activating this induced defense, and air-drying at high temperatures can volatilize nicotine, we examined the hypothesis that the observed leaf ""curing"" behavior decreased nicotine contents. In a natural population, replicate bundles of excised leaves were allowed to dry in the sun for up to 96 hours and harvested in 10 intervals. Even though surface temperatures reached 63° C during drying, no significant loss of nicotine was observed. In the laboratory, significant losses of nicotine were not observed until leaves were dried at 100° C. Nicotine contents of naturally ""cured"" leaf piles at 4 populations were found to be marginally higher than those of neighboring intact plants from which the leaves were likely harvested. We conclude that mammalian ""curing"" behavior does not reduce nicotine contents and may allow the leaves to be used for insect repellant purposes.     

Influence of yellow starthistle ( Centaurea solstitialis ) on small mammals in central California

Yellow starthistle ( Centaurea solstitialis ) is native to Europe and Asia and has quickly invaded disturbed grasslands and rangelands in the western United States. The purpose of our study was to determine the effects of starthistle on rodents at Beale Air Force Base, Yuba County, California, by examining rodent species diversity, species abundance, age structure, and reproductive condition among locations with low, medium, and high percent cover and height of starthistle. Listed in decreasing order of abundance, the rodents were house mouse ( Mus musculus ), California vole ( Microtus californicus ), deer mouse ( Peromyscus maniculatus ), western harvest mouse ( Reithrodontomys megalotis ), and roof rat ( Rattus rattus ). Indices of diversity did not differ among starthistle cover categories. Regression analyses showed that Reithrodontomys megalotis was more abundant in high-cover starthistle plots, with 90.5% of captures occurring in at least 40% starthistle cover. Significant differences were found in capture rates, reproduction, and age between season only. To manage for all rodent species, an area with medium percent cover and height of starthistle will likely provide adequate protective cover.     

Composition and habitat use of small mammals in old-growth mountain forests

Old-growth mountain forests in the Pyrenees have natural gap dynamics, a well-developed shrub layer and a large amount of dead wood. Small mammal communities in two types of old-growth forests, silver fir and mountain pine, were studied in July and September in 2006 and 2007. Four species were trapped: bank vole (Myodes glareolus), wood mouse (Apodemus sylvaticus), garden dormouse (Eliomys quercinus) and common shrew (Sorex araneus). Bank voles and wood mice were most commonly trapped (78% of all captures). There were no differences in community composition in the two forest types, although the bank vole was more often captured in the silver fir than in the mountain pine forest. Mammals were more frequently captured at trap stations with high shrub cover, high tree regeneration cover and low herbaceous cover. Our results show that forest structure and, to a lesser extent, forest type determine small mammal community structure, and specifically fine-scale occurrence patterns, in these old-growth forests.     

Habitat use by small mammals in southeastern Utah, with reference to Mexican Spotted Owl management

We determined temporal and spatial differences in abundance and habitat use by small mammals in southeastern Utah as part of an effort to enhance management of the Mexican Spotted Owl ( Strix occidentalis lucida ), listed by the federal government as threatened. Woodrats ( Neotoma spp.) were captured only in canyons and most frequently in the pinyon-juniper ( Pinus edulis-Juniperus osteosperma ) vegetation type. White-footed mice ( Peromyscus spp.) were found in a variety of vegetation types in both canyons and mesas. The deer mouse ( P. maniculatus ) was generally the most frequently captured species among vegetation types. We found seasonal and yearly differences in relative abundance of each small mammal species. Our data suggest that the pinyon-juniper vegetation type within canyons is an important component of Mexican Spotted Owl habitat.     

Habitat of three rare species of small mammals in juniper woodlands of southwestern Wyoming

Southwestern Wyoming constitutes the northern limit of the ranges of the cliff chipmunk ( Tamias dorsalis ), pinyon mouse ( Peromyscus truei ), and canyon mouse ( P. crinitus ). In addition to trying to determine their presence in the region, we wanted to identify habitat characteristics commonly used by each of these species. We used Sherman live-traps to sample 14 sites representing 2 distinct habitat types in 1998 and 1999: juniper-rocky slopes and juniper cliffs. Seventeen habitat characteristics were measured at capture locations for each species and compared with randomly located points. Best subsets multiple logistic regression was used to construct models that distinguish between used and available habitat for each species. The cliff chipmunk occurred in both rocky slopes and cliffs. The pinyon mouse was also captured in rocky slopes and cliffs and was most often captured in locations in the interior of the juniper woodland with high tree canopy cover, high forb cover, and low density of rock outcrops. The canyon mouse was captured only in cliffs at sites consisting of high forb cover, high rock cover, and high tree density.     

Vegetative and edaphic factors affecting abundance and distribution of small mammals in southeast Oregon

The relationships between vegetative and edaphic habitat factors and the local distribution and abundance of small mammals on Malheur National Wildlife Refuge, Harney County, Oregon, were examined between July 1973 and June 1975. Of 16 species of small mammals captured, deer mice ( Peromyscus maniculatus ), montane voles ( Microtus montanus ), Great Basin pocket mice ( Perognathus parvus ), and least chipmunks ( Eutamias minimus ) comprised 90.1 percent of the individuals. The physiognomy of the vegetation was a factor in the distribution of rodent species other than deer mice. Pocket mice and chipmunks were restricted to the communities dominated by sagebrush ( Artemisia tridentata ) or greasewood ( Sarcobatus vermiculatus ). Population densities of pocket mice and chipmunks were significantly related to edaphic factors such as soil depth, texture, and strength, which may have affected the construction and stability of burrows. Montane voles occurred only in marsh or grassland communities. Population densities of voles were directly correlated with the amount of cover and inversely correlated with its patchiness. Deer mice were the most common species encountered and occurred in all but the grassland communities. The density of this species was related to vegetative or edaphic factors only seasonally or in certain habitats, and few generalizations could be made.     

Maternal defensive behavior of mountain goats against predation by golden eagles

Maternal defensive behavior against predators may appear risky but is common in many species. Herein we describe maternal defensive behavior of mountain goats ( Oreamnos americanus ) against Golden Eagle ( Aquila chrysaetos ) predatory attempts. We found that Golden Eagles attacked goats in 1.9% of sightings ( n = 311 sightings of active Golden Eagles over 12 years) but were never successful. Mothers always defended their young against Golden Eagle attacks. Predation by Golden Eagles on young-of-the-year appears low for most ungulate species, including mountain goats. The benefits of defending offspring against eagles are likely high in ungulates, and we would therefore expect selection to favor maternal defensive behavior.     

Habitat use and food selection of small mammals near a sagebrush/crested wheatgrass interface in southeastern Idaho

Habitat use and food selection data were collected for deer mice ( Peromyscus maniculatus ), montane voles ( Microtus montanus ), Ord's kangaroo rats ( Dipodomys ordii ), and Townsend's ground squirrels ( Spermophilus townsendii ) near a sagebrush ( Artemisia tridentata )/crested wheatgrass ( Agropyron cristatum ) interface in southeastem Idaho. Significantly more captures occurred in the native sagebrush habitat than in areas planted in crested wheatgrass or in disturbed sites. Crested wheatgrass, a prolific seed producer, still accounted for over 30% of the total captures. Montane voles and Townsend's ground squirrels (during periods of aboveground activity) used the crested wheatgrass habitat throughout the summer, while deer mice and, Ord's kangaroo rats exhibited heavy use after seed set.     

Size,spines and crochets: defences of luna moth caterpillars against predation by brown anoles

Field-testing predator-prey interactions between invasive exotic brown anole lizards and sentinel larvae of the luna moth, Actias luna, suggests that late instars of this saturniid, and perhaps many other saturniids, are well defended by their spines and crochets against predation by lizards. However, Actias luna larvae remain vulnerable to anole predation until they reach about 3 cm in length. In contrast, even relatively small caterpillars that are chemically defended, such as those of the io moth, Automeris io, and the monarch butterfly, Danaus plexippus, were shown to be well defended against anoles by their toxins. There is an obvious advantage for caterpillars to be chemically defended. However, there is also a tradeoff: Danaus plexippus are restricted to feeding on a relatively small group of plants, which limits resources and requires specialisation; in polyphagous Automeris io, the constant production of elaborate spines and toxin leads to prolonged larval development, which is at least twice as long as that of Actias luna, and exposes the caterpillars to mortality factors such as parasitism for a longer duration.     

Trapping mammals in a cautious world: the effect of disinfectants on trap success

Disinfecting traps that have captured small mammals is one recommendation for preventing occurrence of hantavirus infection; however, the potential effects of disinfection on small mammal trappability have not been investigated thoroughly. We conducted an experiment to compare the effects of 2 disinfectants (Lysol ® and household bleach) on the trappability of 4 small mammal species ( Peromyscus maniculatus, Neotamias spp., and Spermophilus lateralis ). We established triplicate trap grids in 2 forest types (red fir and mixed conifer), each consisting of a 6 × 6 array of Sherman live-traps placed at 10-m intervals. Traps were given 1 of 3 treatments: control (water), Lysol, or bleach; the treated traps were placed in an alternating pattern. Traps were open for 4 consecutive nights with daily treatment application. We found a difference in the trappability of Peromyscus between years; however, we did not detect a statistically significant difference in trappability resulting from disinfection for any of the 3 study species. Disinfectant effects on capture probability within Peromyscus were not supported by model selection in Program MARK. Collectively, these results indicate that although populations may fluctuate temporally and spatially, trap disinfection does not have a significant effect on small mammal trappability. Una de las recomendaciones para prevenir el hantavirus es la de desinfectar las trampas en las que se ha atrapado a pequeños mamíferos. Sin embargo, no se han investigado extensamente los posibles efectos de la desinfección en la facilidad de captura de los pequeños mamíferos. Llevamos a cabo un experimento para comparar los efectos de dos desinfectantes (Lysol ® y cloro) en la facilidad de captura de cuatro especies de pequeños mamíferos ( Peromyscus maniculatus, Neotamias spp. y Spermophilus lateralis ). Hicimos una cuadrícula triplicada de trampas en dos tipos de bosque (abeto rojo y coníferas mixtas); cada cual constaba de una distribución 6 × 6 de trampas Sherman de captura viva separadas por 10 m. Se lavaron las trampas con uno de tres líquidos: agua (el control), Lysol o cloro. Se colocaron de tal manera que alternaba de forma regular el uso de los tres líquidos. Operamos las trampas durante cuatro noches consecutivas, lavándolas a diario. Detectamos una diferencia en la facilidad de captura de Peromyscus de un año a otro; sin embargo, no detectamos ninguna diferencia estadísticamente significativa en la facilidad de captura que se pueda atribuir a la desinfección para ninguna de las tres especies estudiadas. Para Peromyscus, la selección de modelos en Program MARK no respalda la hipótesis de que la desinfección afecta la probabilidad de captura. Estos resultados indican que mientras que las poblaciones pueden fluctuar temporal y espacialmente, la desinfección de trampas no tiene ningún efecto significativo en la facilidad de captura de pequeños mamíferos.     

Patterns of artificial avian nest predation by introduced rats in a fragmented laurel forest (Tenerife,Canary Islands)

The importance of introduced rats as damaging factors on island biotas is globally recognized. The predation of artificial avian nests by Ship rats (Rattus rattus) in fragmented laurel forests in Tenerife (Canary Islands) was explored. The influence of road edge, patch type, and position (ground versus tree) on nest survival in two forest remnants differing in conservation degree, were assessed using failure‐time analysis. Overall, nest predation was greater in the preserved than in the disturbed remnant. Nest predation also differed among and within patches, variation being greater within the disturbed remnant. The probability of nest failure was higher at the interior than along the road edge in both remnants, but the road edge effect on nest predation was more intense in the disturbed remnant. Predation pressure was higher in patches of mature, closed canopy or dense understorey with stump sprouting. Ground nests were predated at higher rates than tree nests at any location. These results contrast with other nest predation studies in fragmented landscapes where forest edges rather than the interior are more frequently used by predators. Predatory activity by rats seems negatively affected by forest disturbance and road edge effect. Overall, artificial nest predation patterns by rats confirm a potential predation risk for the avifauna of the Canarian laurel forest. This should be considered in implementing conservation management programmes.     

Egestion of plant propagules by turtles in a small Massachusetts river

ABSTRACT

Evidence from flowing-water habitats has confirmed a role of turtles regarding the effective internal transport and viability of riparian plant seeds. We assessed potential propagule dispersal by Eastern painted turtles (Chrysemys picta) within a small river in Massachusetts and factors that may influence the diversity and abundance of egested propagules. From August–October 2015 and June–October 2016, we captured 69 turtles (28 male and 13 female), recorded standard measurements (sex, size, mass, BCI), and collected their faeces from which we isolated propagules. Propagules, mostly seeds, were observed in a small (28%) group of individuals. Overall, 4808 seeds of four taxa and 62 tubers were recovered. Most turtles (58%) defaecated propagules of just one taxon and number of seeds per turtle was highly variable (1–1506, 253.05 ± 414.55 seeds). Taxon richness, abundance, and Simpson Index of propagules varied significantly by sampling year. Sex-year interaction was also a significant predictor of propagule abundance. No turtle-specific features (sex or BCI) have any significant influence on any of the seeds egested. While our study suggests a minor role for C. picta as mobilisers of river plant propagules, these highly vagile animals may still create intermittent links between spatially isolated populations within and between waterbodies.     

Influence of grassland type, nest type, and shrub encroachment on predation of artificial nests in Chihuahuan Desert grasslands

Nest predation on artificial nests was examined in relation to nest type, grassland type, and shrub encroachment in Chihuahuan Desert grasslands in southern New Mexico. Open-cup ground, open-cup shrub, and spherical shrub nests ( n = 210), mimicking Eastern Meadowlarks ( Sturnella magna ), Black-throated Sparrows ( Amphispiza bilineata ), and Cactus Wrens ( Campylorhynchus brunneicapillus ), were placed in 10 grasslands of tobosa ( Pleuraphis mutica ) and black grama ( Bouteloua eripoda ) with low and heavy levels of mesquite encroachment. Nest predation varied among nest types, grassland types, and shrub encroachment, with highest levels of predation occurring on open-cup shrub nests in tobosa grasslands with heavy shrub encroachment. We detected a significant interaction between nest type and shrub encroachment, but not between grassland type and nest type or grassland type and shrub encroachment. Combined predation rates from the 3 nest types were positively associated with shrub density. The encroachment of shrubs into desert grasslands may act as a corridor for a diversity of species historically not associated with desert grasslands to occupy or move through a patch, increasing vulnerability to nest predation.     

Effects of soil structure on burrow characteristics of five small mammal species

Burrows of small mammals can impact a variety of soil processes including organic turnover, aeration, and mineralization rates. The structure of burrows, depth, length, and complexity can influence the extent of the impact burrows have on soil processes. Soil properties, in turn, are thought to affect burrow structure. To increase our understanding of burrow-soil dynamics, we compared maximum depth, total volume, total length, volume:length ratio, and complexity of burrows of five small mammal species with bulk density of soil texture in multiple regression analyses. Burrows of Wyoming ground squirrels ( Spermophilus elegans ) were deeper, longer, and more complex as percentage of silt and clay increased and percentage of sand and bulk density decreased. Average maximum depth of montane vole ( Microtus montanus ) burrows increased as soils became sandier. Length and volume of deer mice ( Peromyscus maniculatus ) burrows increased with increases in bulk density and percentage of clay. Volume, length, and complexity of kangaroo rat ( Dipodomys ordii ) burrows were greater in soils with higher amounts of clay and silt. Townsend's ground squirrel ( Spermophilus townsendii ) burrows did not appear to be affected by the soil properties measured.     

Effects of watershed alteration on the brook trout population of a small Black Hills stream

The impacts of adjacent landscaping activity and livestock presence on the brook trout ( Salvelinus fontinalis ) population of a small Black Hills stream were evaluated. Moderate changes in temperature, turbidity, and fecal coliform numbers did not influence brook trout densities. Stream morphometry, particularly factors affecting stream cover, appeared to have the greatest impact on numbers of trout. Brook trout were poor indicators of moderate changes in water quality, but they were adequate indicators of the physical perturbations within the stream.      

Quaternary paleontology and paleocology of Crystal Ball Cave, Millard County, Utah: with emphasis on mammals and description of a new species of fossil skunk

Crystal Ball Cave is located in a small outlier of the Snake Range in Snake Valley 1.7 km (1 mile) west of Lake Bonneville at its highest level. Original vertebrate skeletal material (mostly mammalian) has been found in shallow dry dust 61 m (200 feet) inside the cave. Radiocarbon dates show that fossils have been accumulating since at least 23,000 Y.B.P. It appears that wood rats and possibly small carnivores transported the fossils into the cave because only the smallest elements of large mammals are represented. The fossil assemblage represents a much more boreal community than the present local fauna. Fish, Ondatra zibethicus , and Mustela cf. vison , which require perennial water, were recovered, as were Ochotona princeps , Lepus cf. Americana , Microtus cf. pennsylvanicus , Vulpes vulpes , and Martes americana , which have also been extirpated from the Snake Range. Marmota flaviventris , Neotoma cinerea , cf. Cervus elaphus , and Ovis Canadensis were recovered but now occur only at higher elevations in the range. Extinct taxa recovered are Smilodon cf. fatalis , Equus species, Camelops cf. hesternus , Hemiauchenia cf. macrocephala , cf. Symbos cavifrons , and a new species of Brachyprotoma , herein named B. brevimala . This is the first recovery of Brachyprotoma from the western United States.