Breeding biology of Mountain Plovers ( Charadrius montanus ) in the Uinta Basin

The known Mountain Plover population breeding on the Myton Bench, Duchesne County, Utah, is small, composed roughly of 30 adults and young after each breeding season. Currently, its location is peripheral to the species main range. This shrub-steppe breeding habitat differs from the shortgrass prairie habitat with which this bird is historically associated. Between 1996 and 1998 we made observations at nesting sites located consistently in 2 concentrated areas surrounded by large tracts of similar habitat. Activity may be focused in these specific areas because of breeding-site fidelity; this behavior is common among most shorebirds and has been documented for the Mountain Plover in Colorado. Also, Mountain Plovers are social and tend to choose nest sites near others. Most nests in Utah were located within close proximity of mounds of white-tailed prairie dogs ( Cynomys leucurus ), and all were situated near roadways or oil well pads. Mountain Plovers were often observed with broods on these bare areas at night. We conclude that Mountain Plovers on the Myton Bench are distributed in clumped breeding colonies within large areas of apparently favorable habitat.     

Centric diatoms of Lake Tahoe

An understanding of the mechanisms of phytoplankton species interaction is dependent on a precise knowledge of what species exist within the community. The centric diatoms of Lake Tahoe, California-Nevada, which are often the dominant component of the phytoplankton community, are presented in both light and scanning electron microscopy (SEM) photographs. Specific attention has been given to initial cell forms of Cyclotella stelligera Cleve and Grunow and C. comta (Ehrenberg) Kützing through the aid of the SEM.     

Fishtail Mesa: a vegetation resurvey of relict area in Grand Canyon National Park, Arizona

Relict sites are geographically isolated areas that are undisturbed by direct and indirect human influences. These sites facilitate long-term ecological monitoring by providing a reference for gauging impacts occurring elsewhere. Knowledge gained through comparing vegetation change on matched relict and proximal disturbed areas can help partition the causes of change into natural and human-produced components. Fishtail Mesa in Grand Canyon National Park is a 439-ha relict site that is inaccessible to domestic livestock. Human visitation is infrequent and irregular, and fires have never been suppressed or managed. In 1958, U.S. Forest Service range scientists conducted a survey of Fishtail Mesa to gather reference data on vegetation, wildlife, and soils. Vegetation sampling was conducted using a method called the ";";elb.";"; We returned to Fishtail Mesa in May 1996 to perform a general vegetation and floristic survey, assess the extent of vegetation change after 38 years, and evaluate the suitability of the site as a location for long-term surveillance of ecological change. Fishtail Mesas vegetation consists primarily of a Pinus edulis (pinyon) and Juniperus osteosperma (Utah juniper) woodland with an Artemisia tridentata (sagebrush) understory, or tree-type (310.9 ha), and an Artemisia and Poa fendleriana (mutton grass) steppe, or shrub-type (127.5 ha). Since 1958 vegetation changes in both shrub- and tree-types have been limited to only a few species. In the shrub-type we detected slight increases from 1958 to 1996 in both Pinus and Juniperus , and reexamination of 1958 photo sites confirmed that Pinus and Juniperus are reoccupying the shrub-type. Artemisia cover declined from 1958 to 1996, whereas Poa increased from near trace amounts in 1958 to moderate cover in 1996. In the tree-type, Poa has increased from 1958 to 1996, while Artemisia , Juniperus , and Pinus showed no apparent change. Other species such as Ephedra torreyana (Torrey joint-fir), Opuntia polyacantha (prickly pear), and Gutierrezia sarothrae (snakeweed) have decreased. Vegetation analysis aided by TWINSPAN revealed that the shrub-type is defined more on the basis of absence of Pinus and Juniperus rather than any special association of differential species with a high preference for this type. We interpret the ";";invasion";"; of the shrub-type by Pinus and Juniperus as a ";";reoccupation.";"; Indirect ordination using DECORANA inferred 2 environmental gradients, a moisture gradient and perhaps a substrate texture gradient, that appeared to influence vegetation distribution on Fishtail Mesa. Fishtail Mesa is a valuable relict area for studying the effects of livestock grazing and prescribed fire. It should be designated a Federal Research Natural Area based on its vegetation communities, size, and protection afforded by its location in Grand Canyon National Park.     

Winter macroinvertebrate communities in two montane Wyoming streams

Macroinvertebrate communities were examined on 4 winter dates over a 4-yr period in 2 high-altitude Rocky Mountain streams to document overwintering assemblages potentially experiencing spring acid pulses. Taxa richness values were comparable to other published lists for alpine and montane stream systems despite the fact that most literature reflected summer collections. Mean benthic density ranged from 1406 to 19,734 organisms/m 2 , and drift rates ranged from 0 to 1740 organisms/100 m 3 . Benthic collections showed higher taxa richness than drift collections while the Ephemeroptera and Plecoptera occurred in greater proportions in drift than in benthos. The Nemouridae (Plecoptera), Ephemerellidae and Heptageniidae (Ephemeroptera), Chironomidae (Diptera), and Hydracarina were the numerically dominant taxa in benthic collections. Grazer/scrapers and shredder/detritivores were always the numerically dominant functional feeding groups at all sites, composing 60-90% of the benthos. Predators, constituting approximately 15% of the community, occurred in the same relative proportion at all sites on all dates. Winter macroinvertebrate communities in these low-order, montane streams exhibit high taxonomic richness and benthic densities as great as lower-elevation mountain streams in the West.     

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.     

Regional assessment of wadable streams in Idaho, USA

There has been a resurgence in applying bioassessment techniques for evaluating and monitoring the biological integrity of stream ecosystms. In all cases biological metrics have been refined to account for regional variation in aquatic habitats and fauna. This study evaluated environmental and macroinvertebrate properties for wadable streams in 3 major ecoregions of Idaho: Northern Basin and Range, Snake River Plain, and Northern Rocky Mountain. These 3 ecoregions constitute > 80% of the land area in Idaho. Reference streams were delineated from test streams in each ecoregion using standard habitat assessment protocols. (Plafkin et al. 1989). Multiple discriminant analysis effectively determined habitat (quantified measures) and macroinvertebrate differences between reference and test streams within ecoregions, although the results suggested that quantifiable habitat measures (e.g., water chemistry and nutrients) and biotic measures based on taxonomic groups (e.g., % Elmidae) improved the discriminatory power of evaluation procedures. Our results support the contention of a multi-metric approach for assessing differences among streams within an ecoregion. Lastly, individual metrics differed in their importance for evaluating stream condition among ecoregions, further emphasizing the importance of regionally stratifying metric selection or scoring procedures.     

Catastrophic wildfire and number of populations as factors influencing risk of extinction for Gila trout ( Oncorhynchus gilae )

We used the computer program RAMAS to explore the sensitivity of an extinction-risk model for the Gila trout ( Oncorhynchus gilae ) to management of wildfires and number of populations of the species. The Gila trout is an endangered salmonid presently restricted to very few headwaters of the Gila and San Francisco river tributaries in southwestern New Mexico. Life history data for 10 extant populations were used to examine sensitivity of the species viability to changes in a variety of factors including population size, fecundity, life stage structure, number of populations, severity and probability of forest fires, and a regulated fishery. The probability and severity of forest fires and number of populations had the greatest effect on viability. Results indicate that successful conservation of Gila trout requires establishment of additional populations and reduction of the severity of forest fires through a program incorporating more frequent, but less severe, fires.     

Grassland bird associations with introduced and native grass Conservation Reserve Program fields in the Southern High Plains

We examined relative abundances of grassland birds among Conservation Reserve Program (CRP) fields seeded with 2 monocultures of introduced grass species and 2 mixes of native grasses in the Southern High Plains of Texas. We assessed bird compositions among these 4 cover types and between the cover types pooled into categories of introduced and native fields. Breeding season bird diversity and total abundance did not differ among cover types or between introduced and native fields. Grasshopper Sparrows ( Ammodramus savannarum ), Cassin’s Sparrows ( Aimophila cassinii ), and Western Meadowlarks ( Sturnella neglecta ) accounted for more than 90% of breeding season detections. Grasshopper Sparrows were the most abundant and found in all cover types. Cassin’s Sparrows were 38% to 170% more abundant among the native seed mix without buffalograss ( Buchloë dactyloides ) compared to 3 other cover types. Although this association was statistically lost when cover types were pooled into introduced or native fields ( U = 93.5, P = 0.91), the species was still 50% more abundant among native CRP than introduced CRP fields. Meadowlarks occurred ubiquitously but at very low numbers during the breeding season. During winter, avian abundance was 44% greater among native CRP than introduced CRP fields. Meadowlarks, Horned Larks ( Eremophila alpestris ), and Savannah Sparrows ( Passerculus sandwichensis ) accounted for 94% of all winter detections. Meadowlarks occurred ubiquitously, but Horned Larks and Savannah Sparrows were 157% and 96% more abundant, respectively, among native CRP than introduced CRP fields. Our data suggest that monocultures of introduced grasses may benefit some bird species but also that native seed mixes may have a more positive influence through increased diversity and abundance of grassland birds. However, pooling cover types into the broader categories of introduced or native grasses may dampen or occlude biologically meaningful results. It may be prudent to avoid broad categorization of CRP fields based solely on native or introduced grass cover when assessing habitat associations of grassland birds.     

Anatomy of rockcress pseudoflowers caused by Puccinia consimilis

Arabis pulchra plants infected by the crucifer rust fungus ( Puccinia consimilis ) develop pseduoflowers. These pseudoflowers are characterized by stems with short internodes and numerous closely spaced, bright yellow leaves coated with a sweet sugary substance. Pseudoflowers do not resemble normal A. pulchra flowers. Pseudoflowers, leaves, and stems of A. pulchra plants infected with P. consimilis and true flowers, stems, and leaves of uninfected A. pulchra plants were fixed, embedded, sectioned, and stained using standard microtechniques. Epidermal, ground, and vascular tissues of true leaves, true petals and pseudopetals were examined and compared for anatomic differences. Examination of anatomic characteristics revealed that pseudopetals are modified leaves.     

New synonymy and new species of American bark beetles (Coleoptera: Scolytidae), Part III

New synonomy is proposed as follows: Metacorthylus Blandford (= Paracorthylus Wood), Corthylus spinifer Schwarz (= Corthylus tomentosus Schedl), Cryptocarinus brevicollis Eggers ( = Cryptocarenus coronatus Wood), Dendrocranulus guatemalensis (Hopkins), n. comb. (= Dendrocranulus parallelus Schedl), Dendroterus mexicanus Blandford (= Conophthocranulus umbratus Schedl), Hypothenemus cylindricus (Hopkins) (= Hypothenemus guadeloupensis Schedl), Hypothenemus erectus LeConte (= Stephanoderes discedens Schedl), Hypothenemus javanus (Eggers) (= Stephanoderes pistor Schedl, Stephanoderes prosper Schedl), Xyleborus pseudotenuis Schedl (= Xyleborus tenuis Schedl), and Xyleborus villosulus Blandford (= Xyleborus coccotrypoides Eggers, villosus Schedl). Scolytodes punctiferus n. n. is proposed for Scolytodes punctifer Wood, 1971 (nec Wood 1969). The following species are named as new to science: Amphicranus argutus, A. fulgidus, A. micans, Pityophthorus inops, P. debilis, P. strictus. P. galeritus. P. sobrinus, P. laetus, P. lenis, P. conspectus P. medialis (Costa Rica), P. perexiguus (Costa Rica and Panama), P. scitulus (Panama), P. costatulus, P. costabilis, P. detentus, P. nebulosus, P. melanurus, P. indigens, P. burserae, P. molestus, P. diligens, P. corruptus (Mexico), P. tenax, P. nugalis, P. minutalis (Guatemala), P. nemoralis, P. morosus, P. hermosus (Honduras), Araptus gracilens (Mexico).