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.     

Associations of Small Mammals Occurring in a Pluvial Lake Basin, Ruby Lake, Nevada

Ruby Lake is a highly mesic and vegetationally diverse pluvial lake basin of east central Nevada. Small mammal associations were examined in six plant communities at Ruby Lake using transects of live traps. Small mammal activity was recorded for these six habitats plus an additional three other specialized habitats. A total of 11 species of small mammals were trapped from the six habitat types; from the entire study area 26 species were trapped or observed. Two greasewood shrub habitats and a shadscale-spiny hopsage habitat held the highest number of trapped species, 6, 5, and 7, respectively. The mesic haymeadow and spring habitats, as well as the big sagebrush-antelope bitterbrush habitat held 4 trapped species each. Peromyscus maniculatus and Perognathus parvus made up 76% of the total captures and were found in all habitat types except marshlands. Eutamius minimus was found in four of the six habitat types, while Dipodomys ordii , Dipodomys microps , Perognathus parvus , and Microtus montanus were limited to specialized habitats. Mesic adapted, wetland species such as Mustela vison , Ondatra zibethicus , and Sorex vagrans possibly dispersed into Ruby Valley from the northeastern drainages and valleys during the late Pleistocene or Holocene.     

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.     

Geographic patterns of ground-dwelling arthropods across an ecoregional transition in the North American Southwest

We examined the biogeographic patterns of ground-dwelling arthropod communities across a heterogeneous semiarid region of the Southern Rio Grande Rift Valley of New Mexico. Our 3 sites included portions of 5 ecoregions, with the middle site a transition area where all ecoregions converged. We addressed the following 3 questions: (1) Do the species assemblage patterns for ground arthropods across habitats and sites conform to recognized ecoregions? (2) Are arthropod assemblages in distinct vegetation-defined habitats within an ecoregion more similar to each other or to assemblages in similar vegetation-defined habitats in other ecoregions? (3) Is there a detectable edge effect with increased arthropod diversity in the area of converging ecoregions? We encountered 442 target arthropod species from pitfall traps operating continuously for 7 years over a series of different habitats at each of the 3 sites. We examined geographic distributions of spider and cricket/grasshopper species in detail, and they showed affinities for different ecoregions, respectively. Each habitat within a study site supported a unique overall arthropod assemblage; nevertheless, different habitats at the same site were more similar to each other than they were to similar habitats at other sites. Overall arthropod species richness was greatest in the area where all 5 ecoregions converged. Arthropod species and their geographic distributions are poorly known relative to vascular plants and vertebrate animals. Findings from this research indicate that ecoregional classification is a useful tool for understanding biogeographic patterns among arthropods.     

Dispersal and extraterritorial movements of swift foxes ( Vulpes velox ) in northwestern Texas

Dispersal plays an important role in the population dynamics of many carnivores, yet little information exists about the dispersal and movement patterns of swift foxes ( Vulpes velox ). We radio-collared and monitored 68 swift foxes for dispersal at 2 study sites in northwestern Texas from January 2002 to April 2004. Dispersal distance for juveniles (13.1 ± 0.3 km, s ), adults (10 ± 4.7 km) and transients (25.4 ± 9.1 km) did not differ by age class ( F = 1.49, df = 2, P = 0.24) or sex ( F = 0.23, df = 1, P = 0.63) but differed by study site ( F = 4.72, df = 1, P = 0.04). Mean dispersal distance from private ranches (PR) was greater than from National Grasslands (NG). Peak dispersal occurred during October– November (13 individuals) and January–February (7 individuals). Dispersal direction was influenced by land-use practices (i.e., toward rangelands and away from anthropogenic features). Direction of dispersal among foxes that occupied the NG was uniform ( n = 16, P = 0.08), whereas foxes from PR dispersed in a northwesterly direction ( n = 18, P ≤ 0.001) away from a town and croplands. Three resident adult foxes made extraterritorial movements. Distances of these movements ranged from 0.2 km to 11.4 km. Distance of extraterritorial movements did not differ by sex ( F = 0.05, P = 0.83), nor by duration of movement ( F = 1.11, P = 0.32). Knowledge of movement distances and patterns is important for conservation and protection of swift foxes and their habitats.     

Vertebrate fauna of a radioactive leaching pond complex in southeastem Idaho

An inventory of the terrestrial vertebrate fauna and the seasonal occurrence of each species was determined for a man - made radioactive leaching pond complex in southeastern Idaho. Three reptile, 11 mammal, and 94 bird species were identified from February 1974 through January 1978. Fewest species were observed during the winter and most during the summer. Eight bird species nested at the pond complex, while 19 species of birds were common or seasonally abundant. It appears that the Test Reactor Area radioactive leaching pond complex is an important water source and provides habitat for some species of wildlife.     

Influence of fire and juniper encroachment on birds in high-elevation sagebrush steppe

We examined relationships between high-elevation sagebrush ( Artemisia spp.) steppe habitats altered by prescribed fire and western juniper ( Juniperus occidentalis ) encroachment on breeding distributions of Brewer's Sparrows ( Spizella breweri ), Vesper Sparrows ( Pooecetes gramineus ), Green-tailed Towhees ( Pipilo chlorurus ), and Sage Thrashers ( Oreoscoptes montanus ) on Steens Mountain in southeastern Oregon. In 2000 we conducted fixed-radius point count surveys at 172 sites encompassing burned and unburned sagebrush habitat and a range of juniper densities. For each bird species we developed habitat models using local variables measured in the field and landscape variables derived from remotely sensed data. Akaike's Information Criterion (AIC c ) was used to select the best-approximating model from a suite of a priori candidate models. Brewer's Sparrows, Sage Thrashers, and Green-tailed Towhees were positively related to increasing local sagebrush cover or percent sagebrush in the landscape, whereas Vesper Sparrows were negatively associated with sagebrush cover and positively related to increases in sagebrush fragmentation at local and landscape scales. Including a measure of juniper encroachment substantially improved models for all species in the analysis. Green-tailed Towhees showed a curvilinear response to the amount of juniper in the landscape. All other species showed a strong negative relationship with juniper. Our results indicate that, although changes in sagebrush habitat associated with fire had a negative influence on sagebrush birds, juniper encroachment due to fire suppression also impacted this high-elevation sagebrush bird community.     

Seasonal population fluctuation and spatial distribution of Orthoptera in two grassland areas of Attica – Greece

The aim of this study was to investigate the seasonal population fluctuation of orthopteran assemblages and determine the spatial distribution of the most abundant species of Orthoptera among two habitats in Greece. A 2-year study was performed in a lowland area and in a mountain grassland area. The family of Acrididae represented almost 75% of the total orthopteran relative abundance in both sampling areas. Dociostaurus maroccanus and Chorthippus bornhalmi were found to be the most abundant species in the lowland and the mountain sampling stations, respectively. Most populated species were spatially aggregated in the lowland station, whereas the abundant species were found to be distributed either aggregately or randomly among sampling units in the mountain area. Shannon–Wiener index estimate was higher for the lowland in 2007 than for the mountain, whereas the opposite was found in 2008. The factors affecting the population dynamics of Orthoptera are discussed.     

Habitat affinities of rodents in northeastern Nevada rangeland communities

From May 1978 through September 1980, baseline data for rodent populations were collected by livetrapping in the Saval Ranch area of northeastern Nevada. The objectives of this study were to determine species composition and relative abundance of rodents for the various range sites. The 3 most abundant and uniformly distributed species were deer mice ( Peromyscus maniculatus ), Great Basin pocket mice ( Perognathus parvus ), and least chipmunks ( Neotamias minimus ). Relative abundance indices and densities reported for most species were similar to those reported in other multiyear studies at similar sites. The composition and relative abundance / density of rodent species was variable among habitats and over time. Diverse rodent species within the sagebrush ecosystem have commensurately diverse habitat requirements that should be considered when vegetation management is planned. Annual population fluctuations and differences among similar habitats should be considered when researchers propose to test rodent population responses to livestock grazing or other habitat treatments.     

Diet switching and food delivery by shrubsteppe passerines in response to an experimental reduction in food

We experimentally reduced the food base of nesting Brewer's Sparrows ( Spizella breweri ) and Sage Thrashers ( Oreoscoptes montanus ) in a shrubsteppe region of south central Idaho in 1989 and 1990. Frequency and mass of "birdfood" arthropods in pitfall, sweep net, and stickyboard samples were generally lower on sites treated with a broad-spectrum insecticide (malathion) than on untreated sites though the effect varied among taxa. In 1990 O. montanus switched nestling diets to prey taxa not affected by the treatment. Time between nestling food deliveries was greater for S. breweri on the treated than untreated site in 1989. In 1990 there were no between-site differences, but there was an increase in delivery time on the treated plot after treatment; this difference was within the range of delivery times recorded on the untreated plot. Malathion applications did reduce the food base, but plasticity in passerine behavior and emergence characteristics of some prey taxa ameliorated indirect effects of food reduction to birds.     

Habitat selection and nest construction behaviour in some Afrotropical species of Ammophila (Hymenoptera: Sphecidae)

Nest construction behaviour and nest site selection are described for seven species of Afrotropical Ammophila.

Four species were atypical in their nest siting. Ammophila beniniensis selected shaded sites in well vegetated habitats, A. vulcania selected small clumps of vegetation in otherwise open habitats. A. insignis nested in vertical banks, old animal burrows and caves. A. braunsi is unique amongst Ammophila in its use of abandoned burrows of other wasps in non-friable clay soils. A. ferrugineipes, A. dolichodera and A. dolichocephala nested mostly in open habitats.

Methods of soil waste disposal, sealing of nests and their final coverage, differed interspecifically, in some cases intraspecifically, but often apparently in response to the habitat.

Temperature conditions, affected by habitat, influenced the depth to which nests were dug by some species. A. insignis switched sites in response to seasonal changes in temperature regimes in vertical banks.

The existence in particular species of both primitive and advanced aspects of nesting behaviour questions their use in assessing the evolutionary status of these species.     

Genetics of allopatric populations of the montane vole ( Microtus montanus ) and Mogollon vole ( Microtus mogollonensis ) in the American Southwest

Variation at 21 allozyme loci and 10 restriction enzymes within the mitochondrial DNA control region was assessed among 3 allopatric populations of montane vole ( Microtus montanus ) in the American Southwest. Among populations of M. montanus , the population from the White Mountains, Arizona, was most genetically divergent. Genetic and biogeographic evidence supported recognition of the White Mountains population as a distinct subspecies, M. m. arizonensis . Results also supported recognition of the Mogollon vole ( Microtus mogollonensis ) as distinct from the Mexican vole ( Microtus mexicanus ).     

Notes on the genus Bombylius Linnaeus in Utah, with key and descriptions of new species (Diptera: Bombyliidae)

A key to the Utah species of Bombylius is presented. Bombylius heximaculatus, nigriventris, montanus, abdominalis, aestivus, and auriferoides, new species, and lancifer kanabensis, subspecies new, are described from Utah. Bombylius lassenensis, new name, is proposed to replace the preoccupied B. pallescens Johnson and Maughan.         

Improved local inventory and regional contextualization for anuran (Amphibia) diversity assessment at an endangered habitat in southeastern Brazil

Amphibians are suffering population declines around the world and the main causes are related to human activities, especially those involving direct habitat destruction. On the other hand, we are far behind in our knowledge of species distribution, natural history and even taxonomy. Some areas are under high levels of threat due to their economic relevance, as is the case for the Quadrilátero Ferrífero, a biodiverse area that is rich in iron deposits in the southernmost highlands of the Espinhaço Mountain Range, in southeastern Brazil. Using four lakes in the Quadrilátero Ferrífero as an example, we aimed to employ two approaches that we believe can improve short-term species inventories such as those needed to meet legal requirements for potentially impacting enterprises (e.g. mining). These approaches were (1) combination of tadpole and adult frog inventories and (2) regional contextualization of local species assemblages. We found adult frog and tadpole sampling to be complementary and representative of all anuran life stages. We also found the studied habitats to be considerably different from all other sampled habitats in the Quadrilátero Ferrífero (which also differed substantially among them). This high spatial heterogeneity could not be explained by geographic distance, even accounting for the effects of different types of bodies of water and sampling methods among sites. These findings have important conservation implications. Thorough inventories including both adult and tadpole stages are recommended for any new potentially destructive enterprise to be implemented in the Quadrilátero Ferrífero, because endemic species and unique anuran assemblages are likely to be lost.     

Diversity and species composition of Araneidae,Tetragnathidae and Nephilidae in different levels of disturbed habitats in Trinidad,West Indies

ABSTRACT

An increasing amount of natural vegetation is being cleared in the tropics, prompting the questions of how disturbance influences the fauna, and the possible value of disturbed habitats as a means to conserve biodiversity. Three habitat types experiencing difference levels of disturbance farmland (most disturbed), cocoa plantations, and secondary forest (least disturbed) were examined in this study. Six localities of each of three disturbed habitat types were sampled for the spider families Araneidae, Tetragnathidae and Nephilidae, and compared to previous data from 46 localities of 16 natural habitats. Observed and estimated species richness, evenness and dominance of orb-weaving spiders differed significantly among the disturbed habitat types, with secondary forest having greater diversity than the mean for natural habitats in all these measures. Overall, disturbed habitats were not significantly different from natural habitats in species richness, evenness and dominance, and were therefore of conservation value.     

Conservation in a changing landscape: habitat occupancy of the critically endangered Tennent’s leaf-nosed lizard (Ceratophora tennentii) in Sri Lanka

Landscape modification is a key driver of global species extinction. Thus, understanding how species react to changes is essential for effective conservation management in modified landscapes. We examined the impact of selected land use patterns on the critically endangered Ceratophora tennentii in the Knuckles mountain range of Sri Lanka where lizards occupy patches of both natural undisturbed forests and modified plantations – evidently, those with a forest canopy. We tested three potential explanations for non-random habitat selection: availability of suitable microhabitat pockets, availability of prey and direct threats from humans. The microhabitat pockets occupied by the lizards were characterised by shade, humidity and the density of perches. Most lizards were found in mixed cardamom forests followed by natural forests and cardamom plantations, but none were observed in the pine plantations. Food availability showed similar patterns among habitats. Direct mortality by humans did not influence the distribution of this species. Our work indicates that habitat modifications that retain the structural complexity of the vegetation would still permit the existence of the species in densities equal to or greater than that of undisturbed forest patches. It adds to a growing body of literature that signifies the importance of disturbed habitats (intermediate disturbance hypothesis) in protecting threatened species of fauna. It is highly unlikely that some disturbed habitats will be ever be returned to their former pristine state in time frames that are important for species’ conservation. Hence, attention is needed in developing suitable approaches to manage and conserve species across disturbed habitats.     

Large mixed-species dispersal flights for predatory and scavenging aquatic Heteroptera and Coleoptera, northern Arizona, USA

We report 4 incidents of large (hundreds to hundreds of thousands of individuals) mixed-species flights of predatory and scavenging aquatic Heteroptera and Coleoptera. The events occurred on normal (mostly clear, calm) autumn 2005 and spring 2006 late afternoons near Flagstaff, Arizona. Flight days were either near the full moon or in advanced waning lunar periods. At least 18 species were involved in the flights, with as many as 16 species (7 species of Heteroptera in 3 families, 9 species of Coleoptera in 2 families) in a single flight. Heteroptera (especially from the family Corixidae) were 2–4 orders of magnitude more numerous than Coleoptera. The diasporas plummeted, with much direct mortality, onto green metal roofs, and the largest event lasted more than 2 hours. Even after 2 days, uninjured individuals failed to resume their flights. The literature suggests that such flights occur for autumn movement to winter habitats or for location of springtime habitats for reproduction. The relative proportions of species in flocks were similar neither to the relative proportions in the region nor to those in nearby livestock watering tanks, indicating that the flights consisted of nonrandom assemblages of species. These events are rare or unique observations of coordinated movement of mixed predatory and scavenging invertebrate species.