Diet of the Mogollon vole as indicated by stable-isotope analysis (δ 13 C and δ 15 N)

There are no published studies on the diet of Mogollon voles ( Microtus mogollonensis ) although this species occurs throughout the Southwest in montane forestlands. Mogollon voles are believed to be herbivorous, selecting the vegetative portion of grass as their dominant food source. Herbivores frequently select more easily digested C 3 plants over C 4 plants; we thus expected Mogollon voles would feed primarily on C 3 plants. We collected hair samples from Mogollon voles captured in northern Arizona between 1967 and 2003 and plant samples from some capture sites. Then we compared stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios to investigate dietary preferences for C 3 or C 4 plants. Mean isotope ratios for C 3 plants we sampled were –26.84‰ ( s = 0.17) for δ 13 C and –0.02‰ ( s = 0.32) for δ 15 N. For C 4 plants, mean isotope ratios for δ 13 C and δ 15 N were –15.04 ‰ ( s = 0.38) and –0.74‰ ( s = 0.55), respectively. Mogollon voles were largely herbivorous based on δ 15 N (mean and standard error: 3.77 ± 0.17‰) and used C 3 plants more than C 4 based on δ 13 C (–24.21 ± 0.14‰). Activities that lead to changes in plant species composition or reduction in C 3 plants in montane grasslands and forests (e.g., excessive ungulate grazing) may reduce habitat quality for Mogollon voles.     

Life cycle and incidence of Diplostomum spathaceum Rudolphi (1819) (Trematoda: Diplostomatidae) in Utah

Diplostomum spathaceum (Trematoda: Diplostomatidae) causes a disease known as diplostomatosis (eye fluke disease) and has been found to be widespread throughout the fish of Utah. Totals of 756 snails (5 species), 893 fish (21 species) and 6 species of birds were examined for the presence of larval and adult D. spathaceum from 17 collecting sites throughout Utah. Pathologic effects such as blindness, subacute inflammatory reactions, cornea perforation, and ruptured globe due to diplostomatosis upon the fish host are listed. Fish host and parasite infection data of D. spathaceum for the major lakes of Utah are given.     

Sampling effort and vegetative cover estimates in sagebrush steppe

The goal of this study was to identify relationships between sampling effort, using a point frame, and the precision of estimates of vegetative cover in sagebrush steppe. Data for 208 point-frame samples were randomly drawn and 95% confidence intervals were identified for varying sample sizes of individual species and species groups. Confidence interval widths decreased rapidly as sample sizes increased from 1 to 50, and more slowly as sample sizes were increased further. For the more abundant species, sample sizes of fewer than 50 frames were sufficient to reduce the 95% confidence interval to less than one-half of average cover. For species with average cover less than 5%, the sample size required to achieve the same relative confidence was much larger. Analyses were repeated to compare point frames with 36 versus 50 sample points per frame. Using a point frame with 50 sample points decreased the number of frames required to achieve the same level of confidence; however, the reduction in sample size was less than the 28% reduction in sample points per frame. Because of the time required to establish transects and position the point frame, it may still be worth sampling more points per frame.     

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.     

Ecomorphology and habitat utilization of Echinocereus engelmannii and E. triglochidiatus (Cactaceae) in southeastern California

The relationship between form and habitat utilization of Echinocereus engelmannii and E. triglochidiatus was studied in southeastern California. The major difference in form is in the density of stems comprising the canopy. These differences in morphology create differences in the daily heat loads of each species. Echinocereus triglochidiatus, with its stems densely packed and in contact with each other over much of their lengths, continues to gain heat internally as the sun sets due to conductance between the stems. In contrast E. engelmannii, with a more open canopy, begins to lose heat as the sun goes down. As a result, E. triglochidiatus is successful in the juniper - pinyon zone where winter temperatures are cold for long periods and E. engelmannii is more successful in the lower desert regions where very hot, summer temperatures prevail. In the latter case, daytime buildup in heat load is reduced by convective cooling as air moves through the open canopy. Differences in microhabitat utilization occur that provide a second mechanism to reduce daily heat load buildup on hot summer days in the juniper - pinyon zone.     

Contrasting movement and activity of large brown trout and rainbow trout in Silver Creek, Idaho

Recent radiotelemetry studies demonstrated that stream-dwelling trout are mobile, but few have compared sympatric species. We used radiotelemetry to simultaneously monitor positions of 20 brown trout and 21 rainbow trout from May or June 1994 to February 1995 in Silver Creek, a small spring-fed stream in south central Idaho. Our biweekly observations from May to September indicated that rainbow trout had larger home ranges (medians, 606 m v. 131 m) and moved greater distances (medians, 1109 m v. 208 m) than brown trout. Furthermore, rainbow trout used more positions than brown trout (means, 7 v. 3) over this interval. Hourly diel monitoring revealed no significant difference in 24-h home ranges of rainbow trout and brown trout (means, 77 m v. 105 m). However, activity patterns of the 2 species differed; rainbow trout activity was usually highest during the day, whereas brown trout activity tended to peak at night. Differences in foraging strategies and response to disturbance may be responsible for differences in mobility.     

Edward Williams Morley and the Atomic Weight of Oxygen: the Death of Prout's Hypothesis Revisited

Prout's hypothesis was influential in—if not necessary for—the establishment of the atomic weight of oxygen, a figure conclusively demonstrated in 1895. Ironically, the successful determination of oxygen's weight also led to a final refutation of the hypothesis (at least the hypothesis in the classical sense). But more than this, the end of Prout's hypothesis via the determination of oxygen's atomic weight was due to three fundamental changes that characterized the way chemistry was practised and communicated in the late nineteenth century. First, encyclopaedia‐like presentations of past atomic‐weight investigations became the focus in numerous and influential studies. Second, there was a dramatic change in the way professional publications presented investigations and experiments, characterized by experimental detail and apparatus design at the expense of theoretical discussion. Finally, the production of hydrogen became the focus of research, as it was one of the principal components of any investigation into atomic weights. Here I present Prout's hypothesis in its historical context by focusing on these three developments and their influence on the research of Edward Williams Morley. While doing so I also illustrate the way marginalized scientists were able to take advantage of their otherwise dubious position and participate in an active and important role in atomic‐weight investigations.     

Monoterpene concentrations in litter and soil of singleleaf pinyon woodlands of the western Great Basin

Mean monoterpene content of singleleaf pinyon ( Pinus monophylla [Torr.] Frem.) litter from stands growing on two soil series was 340 ± 310 ug/g air dry weight (adw). Individual monoterpene hydrocarbons suggested as potential allelopathic compounds occur in extremely small amounts, 0.5-1.10 ug/g adw. Mineral soils contained 50 times less total terpene, 6.6 ug/g ± 4.8 adw, than the litter immediately above. Results suggest that allelopathic effects would more likely occur in litter than mineral soil. These findings are substantiated by previous reports of decreased emergence and growth of herbaceous species in pinyon litter but not mineral soil.     

Two new species of fleas of the genus Meringis (Siphonaptera: Hystrichopsyllidae)

Two new species of Meringis are described. Meringis disparalis, n. sp., has been most commonly taken from Dipodomys merriami but has also been taken from D. ordii and Onychomys leucogaster. Collection localities include the counties of Dona Ana, Eddy, and Luna in southern New Mexico. Meringis facilis, n. sp., has been taken from D. ordii, several other rodents, and Sylvilagus audubonii. Collection localities include Crowley County, Colorado, and Bernalillo, Chaves, and Valencia counties in New Mexico. A key to the species of ♂ Meringis is given.