Avian use of harvested crop fields in North Dakota during spring migration

Broad-spectrum herbicide applications and improved harvesting efficiency of crops have reduced the availability of weed seeds and waste grains for game and nongame wildlife. Over the last decade, corn and soybean plantings have steadily increased in the Prairie Pothole Region (PPR) of North Dakota, while sunflower plantings have declined. The PPR is an important corridor for migratory birds, and changes in food availabilities at stopover habitats may affect how food resources are used. In early spring 2003 and 2004, we compared bird use of harvested fields of sunflower, soybeans, small grains, and corn in the PPR of North Dakota. Across both years and all crop types, we observed 20,400 birds comprising 29 species. Flocks of Lapland Longspurs ( Calcarius lapponicus ) and Horned Larks ( Eremophila alpestris ) and flocks of Red-winged Blackbirds ( Agelaius phoeniceus ) made up 60% and 15%, respectively, of the bird counts. We found that species richness and bird densities were higher in harvested sunflower fields and cornfields than in harvested small-grain and soybean fields, with soybean fields harboring the fewest species and lowest bird density. Blackbird densities tended to be lower in fields tilled after fall harvest than in fields not tilled. These results suggest that some granivorous bird populations in the Northern Great Plains could be positively affected by planting of row crops with postharvest vertical structure (e.g., sunflower, corn) and use of no-till land management practices.     

Evaluating the use of morphometric measurements from museum specimens for sex determination in Mountain Plovers ( Charadrius montanus )

The Mountain Plover ( Charadrius montanus ) is a shorebird species endemic to the dry, terrestrial ecosystems of the Great Plains and southwestern United States. Breeding Bird Survey data suggest that Mountain Plover populations have declined by > 60% in the last 30 years. A better understanding of the population dynamics of the Mountain Plover is important in determining future management goals for this species. However, this effort is hampered by the inability to determine the sex of Mountain Plovers accurately under field conditions. In an effort to develop a simple method for sexing plovers in the hand, we measured external morphometric characteristics from 190 museum specimens of adult Mountain Plovers in alternate (breeding) plumage. Logistic regression and discriminant function analyses were performed on 10 external morphometric measurements (lengths of unflattened wing chord, 10th primary, central rectrix, outer rectrix, total head length, exposed culmen, culmen, bill depth, bill width, and tarsus). The results of these analyses indicated that Mountain Plover sexes were similar for all measures except culmen length. However, further analysis determined that culmen length accurately predicted sex in less than two-thirds of the specimens, suggesting that this measure is a poor predictor of sex in Mountain Plovers. Structurally, Mountain Plovers appear to be nearly identical between the sexes, and other methods of sexing birds (e.g., plumage characteristics, behavioral observations, or molecular markers) should be further assessed for devising a simple method for sexing Mountain Plovers under field conditions.     

Stream channel and vegetation changes in sections of McKnight Creek, New Mexico

Measurements taken at three-year intervals between 1977 and 1985 of channel morphology and vegetation cover between sections inside and outside a cattle exclosure showed that channels increased in depth and width on all plots. Tree canopy cover decreased significantly between 1977 and 1985, but changes in density of trees and shrubs and herbaceous cover were small. Exclusion of cattle use did not prevent channel erosion or deterioration of vegetation; rather, changes were attributed to a wildfire in the headwaters and subsequent storm events that temporarily upset the dynamic equilibrium of the stream.     

Carapace ontogeny of the bromeliad dwelling ostracod Elpidium bromeliarum Müller, 1880 (Crustacea: Ostracoda)

Ostracods have discontinuous development, marked by ecdyses, and determinate growth. Ontogenetic studies have suggested a pattern of nine postembryonic stages (eight juvenile phases and the adult) for the main freshwater ostracod superfamilies Cypridoidea, Cytheroidea and Darwinuloidea. However, cases of a supposed extra moult in the adult stage have been proposed for some ostracod species, which would amount to 10 postembryonic growth stages. One such example is Elpidium bromeliarum Müller, 1880, a cytheroidean that inhabits tank-bromeliads. The present study is aimed at investigating the ontogenetic development of E. bromeliarum using width and length measurements, as well as carapace and appendage morphology in order to test the existing hypothesis of an additional growth stage in adults of this species. Our results revealed nine postembryonic growth stages (eight juvenile and the adult), with sexual dimorphism beginning its expression in the last juvenile stage. Thus, the ontogenetic development of E. bromeliarum agrees with the overall pattern observed for podocopid ostracods and the hypothesis of 10 postembryonic growth stages was not corroborated. We argue that the inability to differentiate juveniles from adults, or different species from one another, may have misled to the assumption of an additional moult in E. bromeliarum.     

Breeding biology of the Double-crested Cormorant on Utah Lake

Research on the nesting of the Double - crested Cormorant ( Phalacrocorax auritus auritus ) was undertaken to determine the breeding biology of the bird on Utah Lake, Utah County, and the possible effects that diking Provo Bay would have on the cormorants breeding there. In 1973, two colonies in Provo Bay were visited weekly to determine laying dates, incubation period, clutch size, and hatching dates. Another colony, located on the dike of the Geneva Steel Works Reservoir near Orem, was visited daily during the spring and summer of 1973. At this colony egg-laying occurred from 13 April to 17 May. The average clutch size was 3.8, and the egg length and width averaged 60.50 mm x 39.05 mm. The average period of incubation was 28 days, and 29.5 percent of the eggs hatched, beginning on 20 May and ending on 9 June. The young weighed an average of 36 gm at hatching with a beak length of 17 mm and tarsometatarsal length of 11 mm. These measurements increased to 1543 gm, 73 mm, and 58 mm, respectively, in 23 days. The cormorant population on Utah Lake may be severely reduced by the proposed diking of Provo Bay.     

Ontogenetic and habitat-related changes in diet of late larval and juvenile suckers (Catostomidae) in Upper Klamath Lake, Oregon

We describe ontogenetic patterns in the diets of shortnose and Lost River suckers (15.8–92.8 mm standard length) from Upper Klamath Lake in summer 1999. Both species made a transition from surface and planktonic prey to benthic prey at about 20–30 mm standard length, corresponding to the approximate size of the juvenile morphological transition. Surface prey was dominated by adult chironomids and undigestable pollen, while benthic prey was dominated by larval chironomids, chydorids, and ostracods. In the 15–20-mm size class, pollen made up >75% of food particles in 68% of specimens, and only 2 specimens in this size class lacked any pollen grains. A better understanding of the prey selection process in larval suckers is needed to determine the importance of this potential source of starvation. The planktonic prey eaten during the surface-to-benthic feeding transition were widely distributed in the lake, suggesting that larvae use emergent vegetation primarily as a refuge from predators. On a numerical basis, crustaceans and larval chironomids contributed most to the diets of larger juveniles. In specimens >40 mm, shortnose suckers ate more Tanytarsini and Lost River suckers ate more chironomid pupae and chydorids. In specimens >40 mm there was a strong habitat-related difference in diet: specimens collected in offshore samples ate more chironomid larvae and pupae, harpacticoid copepods, and chydorids, whereas onshore specimens ate more cyclopoid copepods and invertebrate eggs. The transition from onshore to offshore habitat appears to occur over a broad size range of about 40–90 mm.     

Breeding movements and reproductive activities of porcupine in the Great Basin Desert

I assessed movements of North American porcupines ( Erethizon dorsatum ) in the Great Basin of northwestern Nevada in relation to reproductive activities during the late summer and fall periods of 1991 and 1992. Porcupines exhibit a mate-defense polygynous mating system and I hypothesized that (1) competitively dominant males would have larger home ranges than both subordinate males and adult females, and (2) variation in home range size among adult male porcupines would be positively correlated with reproductive success. Results indicated that dominant male porcupines ranged over larger areas (average 95% minimum convex polygon home range = 20.7 ha) than subordinate males (average 95% MCP home range = 2.9 ha) and adult females (average 95% MCP home range = 8.2 ha). Analyses of movements in relation to body size and energetic requirements revealed that home ranges of dominant male porcupines were larger than predicted based on body size (approximately 10.2 ha). Breeding period home ranges of dominant male porcupines encompassed portions of the home ranges of 3 to 10 adult females, and indices of reproductive success based on observations of mate-guarding behaviors suggested a strong positive relationship between home range sizes of male porcupines and mating success. Together these data suggested that larger home ranges among dominant males were related to increased mating opportunities and not increased metabolic requirements associated with larger male body sizes. In the study area, however, female porcupines congregated around small, patchily distributed riparian areas, and dominant males with relatively small home ranges encompassing riparian areas may have gained mating access to multiple females. Finally, analyses of overlap among core home ranges (60% MCP) of adult male and adult female porcupines suggested that both sexes maintained relatively exclusive core home range areas, with males exhibiting significantly less range overlap with other males ( ￣x = 9.4%) than females with other females ( ￣x = 27.1%). It is possible that the small, patchily distributed riparian areas in this desertlike area were such a limited resource that females were unable to maintain exclusive use of their home range areas.     

Avifauna of the Mt. Dellenbaugh region, Shivwits Plateau, Arizona

An investigation of the avifauna of Mt. Dellenbaugh, Arizona, and nearby areas on the Shivwits Plateau was conducted during fall 1974 and during spring and summer 1975. A total of 92 species of birds was recorded, of which 56 were considered resident. Species composition is discussed in relation to habitat.     

Temporal changes in burrow structure of the thalassinidean ghost shrimps Trypaea australiensis and Biffarius arenosus

The thalassinidean ghost shrimps Trypaea australiensis and Biffarius arenosus are dominant burrowing macroinvertebrates of soft‐sediment habitats in Western Port, Victoria, Australia. Burrow structure has been described for both species but little is known about how the burrows change over time. This study used resin casting to investigate temporal variation by making burrow casts each month over a 12‐month period. It was found that the overall burrow morphology of both T. australiensis and B. arenosus was consistent over time, but in the warmer months (summer and spring), both species constructed burrows that were deeper and of greater volume than burrows constructed in winter and autumn. Possible reasons for this variation are discussed.     

Reproduction and seasonal activity of silver-haired bats ( Lasionycteris noctivagans ) in western Nebraska

Silver-haired bats ( Lasionycteris noctivagans ) were thought only to migrate through Nebraska; however, recent surveys in eastern Nebraska report summer records of females and their young. Our study in western Nebraska also shows that silver-haired bats are summer residents. We discovered the 1st reproductively active L. noctivagans in this part of the state. We caught lactating females and volant young in riparian forests along the North Platte River and in forested areas of the Pine Ridge. Previously, adult males were not known from Nebraska in summer, and only 4 records of L. noctivagans were known from western Nebraska during migration. On 28 July we captured an adult male in a coniferous forest of the Wildcat Hills, and we have more than 100 records of migrating individuals. Lastly, an obese L. noctivagans captured on 4 November may represent an individual preparing to hibernate in the state.     

Seasonal abundance and life cycle of Archaeomysis articulata (Crustacea: Mysidacea) on a sandy beach of western Hokkaido,Japan

Abundance and life cycle of the sandy beach mysid Archaeomysis articulata Hanamura were investigated based on seasonal collections over 2 years in the surf-swept intertidal zone of an open sandy beach in Ishikari Bay, western Hokkaido, Japan. The number of mysids in the intertidal zone increased from winter to spring, reaching its maximum in summer to autumn (average >2500 ind. m^-2), and decreased considerably towards the end of the year. The abundance was maintained at a minimal level (<200 ind. m^-2) throughout the winter. The breeding season was March to November, during which the liberation of young was most intensive from late April to mid-October. Three alternate generations, including overwintering, spring and summer generations, were suggested from field observations. Archaeomysis articulata is primarily iteroparous; only a restricted number of breeding females could produce more than two broods. The life span was estimated to be 7–9 months for the overwintering generation and 2.5–3.5 months for the spring–summer generations. The sex ratio fluctuated at samplings, with a tendency toward female dominance (overall mean=54%). The number of embryos carried by a single female ranged from 16 to 94, tending to increase with increasing size of females. The size of egg-like embryos varied seasonally from 0.45 to 0.54mm, being largest in spring and smallest in summer, with no correlation to the length of females; water temperature is considered an important factor in regulating the size of eggs. The embryonic development time was estimated to be 1.5 months for the spring generation (water temperature 5–10°C), and much shorter than this for the summer and overwintering generations. The mortality rate during embryonic development was estimated to be 7–18%.     

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.     

Large-scale effects on bird assemblages in desert grasslands

During winter 1996&ndash;1997 and summer 1997, we surveyed birds at 26 study sites in desert grasslands of Arizona and New Mexico to determine tolerance of birds to variability in plant composition and structure. The relationship between bird abundance and vegetative characteristics might be an important consideration in the development of management and restoration plans. Of the 49 bird species we observed, we examined 13 and 16 species in detail for winter and summer seasons, respectively. A noticeable shift in species composition occurred between 3% and 10% woody plant cover. During winter, Chestnut-collared Longspurs ( Calcarius ornatus ) and Horned Larks ( Eremophila alpestris ) showed significant positive relationships with grass cover and negative relationships with woody plant cover, occurring in greatest numbers where woody cover was &#60;1%. The richness of sparrow species during winter was highest among sites with 6% to 15% woody plant cover. In addition to showing significant positive relationships with woody cover, Vesper Sparrows ( Pooecetes gramineus ), Black-throated Sparrows ( Amphispiza bilineata ), Brewer&rsquo;s Sparrows ( Spizella breweri ), and Chipping Sparrows ( S. passerina ) showed significant positive relationships with shrub species richness. Our results showed that reductions of woody plant cover below 3% in combination with the presence of native grasses could substantially enhance the presence of several bird species. Maintenance of woody cover between 6% and 15% could increase use by a suite of other species, especially wintering sparrows.     

An ontogenetically stable sexual character in a montane agamid,Salea horsfieldii Gray, 1845 (Reptilia: Agamidae) from Nilgiris,India

Many agamid lizards are known to show sexual dimorphism in body shape, colour and ornamentation or a combination of these traits. Adult males of Salea horsfieldii have a discontinuous dorsal crest at the nuchal region, which is a sexually dimorphic character. However, there is no information about the age or size at which this dimorphic ornamentation develops and if the species exhibits sexual shape dimorphism (SShD). The authors studied the morphology of S. horsfieldii and found that its ornamentation is an ontogenetically stable character present in all males, including juveniles. Seven morphological characters were measured to determine if they exhibited SShD at adult and juvenile stages. Analysis of covariance was used to identify differences in morphology between sexes. The results show that only adults exhibited SShD, but not juveniles. Adult males had larger head and foot lengths in comparison to females of the same size. Larger head length in adult males is a sexual fitness trait, which increases bite-force during intra-sexual combats. Although the presence of sexually dimorphic ornamentation right from the juvenile stage is rare in agamids, S. horsfieldii is an exception . The role of sexually dimorphic ornamentation at juvenile stages remains unknown and requires further investigation.     

Observations on Double-crested Cormorants ( Phalacrocorax auritus ) at sportfishing waters in southwestern Utah

Counts of Double-crested Cormorants ( Phalacrocorax auritus ) were made at 13 reservoirs and lakes in southwestern Utah during 1989-91 to determine current abundance of that species. Food habits of cormorants were studied at three of the reservoirs in 1989. Data were also collected on trout abundance during standardized gill-netting to make comparisons between cormorant numbers and trout abundance. Cormorants were observed at all waters studied except one and were generally most numerous during the spring as they migrated through the area. Estimated cormorant abundance ranged from 0 to 34 bird-days per ha and was highest at the larger, lower-elevation reservoirs. Cormorants were summer residents at several of the larger reservoirs and nested successfully at Piute Reservoir. Trout accounted for 24-81% of the diet of cormorants, with Utah chubs constituting most of the remainder of the diet. Estimates of the annual consumption of fish by cormorants ranged from 0 to 15.8 kg per ha. The index of trout abundance was inversely related to cormorant abundance ( P < .01) at the waters studied. Cormorants apparently have increased in numbers and extended their range in southwestern Utah during the past decade. This change may be the result of factors that have led to similar changes throughout North America as well as some factors unique to Utah. Methods to mitigate the impact of predation by piscivorous birds of sportfisheries are discussed. The Utah Division of Wildlife Resources has initiated a new management plan at Minersville Reservoir that incorporates piscivorous birds into sportfish management at that reservoir.     

Comparisons of the alpine bird communities across habitats and between autumn and winter in the mid‐Yalong Zangbo River valley,Tibet

The extreme alpine environment around the mid‐Yalong Zangbo River on the Tibetan plateau supports a unique avifauna. To understand the structure and habitat selection of this poorly known bird assemblage, we quantified abundance of the birds in four representative types of vegetation and a human settlement inside a shrub‐covered alpine valley (29°27′N, 91°40′E, 4000–5200 m a.s.l.) in the Lhasa mountains, Tibet, from September 2004 to January 2005. A total of 40 species of birds was recorded, six of which were summer breeders, one vagrant autumn migrant, 29 permanent residents, and four local wintering migrants. Latitudinally migrating taxa were absent. Of the 33 wintering species, 70% were alpine specialists. Patterns of distribution of species and individuals differed across habitats. The highest bird species richness was found in Rose–Barberry shrub where vegetation was most complex, and fruiting and seeding plants abundant. From autumn to winter, birds tended to aggregate in the human settlement for foods supplemented by local Buddhists; as a consequence this habitat contained the highest individual density. In terms of trophic guilds, plant‐eating birds were predominant in composition (65.8–75.8%) and numerically abundant (89.8–96.7%) in all the habitats. We concluded that vegetation diversity and food supply significantly influence species composition and individual abundance of the alpine bird community. For long‐term survival of the unique bird assemblage, we argue for protection of the shrub vegetation as it is difficult to regenerate in the harsh high‐altitude conditions.     

Composition and abundance of periphyton and aquatic insects in Sierra Nevada, California, stream

The species composition of periphyton and benthic insect communities and abundances of common taxa (&;gt;0.1&;#37; of individuals) were examined during snow-free months in Convict Creek, a permanent snowmelt- and spring-fed stream in the Sierra Nevada of California. The communities were highly diverse. The most abundant taxa in the periphyton were diatoms ( Achnanthes minutissima, Cocconeis placentula lineata, Cymbella microcephala, C. sinuata, Fragilaria construens, F. crotonensis , Navicula spp., Synedra acus , and S. rumpens ), except in late spring and summer when several seasonal blue-green algae ( Chamaesiphon incrustans, Lyngbya spp. and Oscillatoria spp.) are at their maximum densities. Most common periphyton taxa vary systematically in abundance with season, but relative abundances of taxa also appear to be influenced by streambed scouring and by concentrations of ambient nutrients. Data on population densities and length frequencies of larval and nymphal stages of common benthic insects and occurrences of pupal and adult stages were examined to determine life history patterns. Taxa hatching in winter and spring and abundant as immatures in late spring include ephemeropterans ( Epeorus longimanus, Drunella flavilinea , and Caudatella heterocaudata ), plecopterans ( Calineuria californica, Doroneuria baumanni, and Pteronarcys princeps ) and dipterans ( Cryptolabis sp.). Common taxa hatching in late spring or summer are the plecopteran Malenka ( californica? ) and the trichopterans Arctopsyche grandis and Rhyacophila acropedes . Several bivoltine and multivoltine ephemeropterans ( Baetis devinctus and B. tricaudatus ) and dipterans ( Simulium spp. and Chironomidae) have summer cohorts. Taxa hatching in late summer or autumn and most abundant in autumn include ephemeropterans ( Baetis spp., Ephemerella infrequens, Epeorus dulciana, Ironodes lepidus , and Paraleptophlebia pallipes ), trichopterans ( Hydropsyche oslari, Lepidostoma spp., Glossosoma califica, Micrasema sp., Brachycentrus americanus, Neophylax sp., and Rhyacophila vaccua ) and dipterans ( Antocha monticola, Pericoma sp., and Chironomidae). Major recurring events that may influence life history patterns and structure of the benthic insect community are (1) near-freezing, nighttime winter water temperatures and occasional anchor ice, (2) a prolonged period of high discharge in late spring and early summer (3) a brief summer, and (4) a prolonged period of moderate stream discharge in autumn when the substratum is stable and food is abundant.     

High prevalence of blood parasites in hawfinch Coccothraustes coccothraustes

Fifty-seven hawfinches Coccothraustes coccothraustes were caught in May–June 1982–2001 on the Curonian Spit in the Baltic Sea and investigated by microscopical examination of stained blood films. Haemoproteus fringillae, H. tartakovskyi, Leucocytozoon dubreuili, L. fringillinarum, L. majoris, Plasmodium relictum, P. vaughani, Trypanosoma avium, T. everetti, and microfilariae were identified. The overall prevalence of infection was 100%. Prevalences of Haemoproteus spp. (89.5%), Plasmodium spp. (61.4%), Leucocytozoon spp. (78.9%), Trypanosoma spp. (26.3%), and microfilariae (29.8%) were recorded. No differences were discernible in parasite fauna, prevalence, or intensity of infection between males and females or between young and adult birds. The majority of infections (86.0% of all birds) were mixed, with parasites from two to five different genera present in each blood smear. These birds were failed breeders migrating through the Curonian Spit. It is probable that heavy haematozoan infections can influence the breeding success of birds.     

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.     

Morphology of ephemeral and persistent leaves of three subspecies of big sagebrush grown in a uniform environment

Measurements were made of morphological characteristics of ephemeral and persistent leaves of three subspecies of big sagebrush ( Artemisia tridentata Nutt.) grown in a uniform environment. No morphological feature clearly separated the subspecies. Genetic - environmental interactions on leaf morphology apparently reduce its value as a sole criterion for distinguishing the subspecies. &nbsp;