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1.
Burrowing Owls ( Athene cunicularia ) occupy intensively managed agricultural areas within the Imperial Valley of California, where they occur at high densities relative to other areas in the state, and yet reproductive rates are often low. Understanding diet and food-niche breadth may lead to insights into factors contributing to their poor reproductive performance. We tested the relative contribution of sex, year, and season on diet composition and food-niche breadth from analyses of stomach contents of adult Burrowing Owls ( n = 53). Orthoptera dominated the diet; it accounted for 58.9% of the total number of prey items in all stomachs and was found in 98.2% of all samples. Rodents, a source of potentially limiting dietary calcium, were found in only 2 stomachs. We detected yearly and seasonal effects on estimated food-niche breadth. Mean food niche for the breeding season was broader (antilog of Shannons index: 2.38 ± 0.15) and more even (Pielous index: 0.67 ± 0.06) than for the nonbreeding season (1.83 ± 0.13, 0.49 ± 0.07, respectively) partially because of a greater frequency of Araneida, Isopoda, Lepidoptera, and Solpugida in the diet during the breeding season. Mean food-niche breadth for 1997 (2.25 ± 0.23) was broader than during 1994, 1995, and 1996 (2.07 ± 0.23, 1.98 ± 0.20, and 1.82 ± 0.40, respectively) because of a greater frequency of Araneida, Dermaptera, Isopoda, Lepidoptera, and Solpugida. These results, and auxiliary diet information, suggest rodents were infrequent in the diet of Burrowing Owls in the Imperial Valley and may help explain their lower reproductive success relative to other areas of California. 相似文献
2.
Lepidomeda albivallis (White River spinedace), a fish species endemic to the White River, Nevada, appeared headed toward extinction. In 1991 only 1 population remained, and it comprised fewer than 50 individuals in a 70-m stream reach. We monitored population recruitment and distribution and studied life history and habitat use from 1993 through 1998. We determined that L. albivallis was not reproducing and was continuing to decline, and as an emergency measure we relocated the population (14 in spring 1995 and 6 in spring 1996) downstream 200 m to a secure habitat that we judged more favorable for reproduction. The relocated population reproduced, and by September 1998 it had increased to 396 individuals that inhabited more than 1 km of stream including both pond and stream habitats. In streams they oriented near the bottom but frequently moved up in the water column to strike at drift items. Gut analysis of museum specimens indicated L. albivallis is omnivorous but feeds primarily upon aquatic invertebrates. Conservation of L. albivallis will require reestablishing additional populations within its former range. 相似文献
3.
Mining in the Upper Arkansas catchment has polluted the river with heavy metals for 140 yr. Pupal and adult chironomid species distribution and sedimentary metal concentrations are provided for 22 stations along 259 km of main river during 1984-85. Complete species identification was achieved only recently. This has produced an unprecedented record of chironomid species distribution for a comparable length of river in the USA. Chemically or physically perturbed sites had poor species richness compared with the next site downstream, suggesting that larvae may drift through unfavorable habitats to benign ones. Using canonical correspondence analysis, we found species composition to be most strongly related to variables expressing the longitudinal axis of the river (distance/altitude, temperature, latitude), while toxicity to zinc was a significant secondary correlate. These river-related environmental variables accounted for a greater proportion of pupal species variation than for adults. This was considered to result from a proportion of adults emerging from habitats beyond the main river. Multivariate analysis identified metal-tolerant and -intolerant species. Generic data revealed the same major trends but indicator taxa were lost. The study provides a disturbed-state reference for monitoring effects of remedial actions begun in 1991, and for comparisons with other Colorado rivers. 相似文献
4.
The Upper Arkansas catchment has been polluted with heavy metals from mining for almost 140 yr. Adult Plecoptera and Trichoptera species distributions were recorded from 22 stations along 259 km of main river during 1984-85 so that these could be related to metal deposition and other environmental characteristics. Chemically or physically perturbed sites had poor species richness compared with adjacent sites. There was no sequential downstream increase in species numbers. Filter-feeders proportionally increased downstream as predators declined; these proportions were reset at a high-energy site before the trend resumed. Using canonical correspondence analysis, we found that species composition was most strongly related to changes in distance/altitude and to temperature, particularly after regulatory flows entered the river. The proportion of biological variation explained by river measurements indicated that collected adults were largely derived from the main Arkansas River. Species tolerant of high sedimentary metal concentrations were identified while some other species appeared to be sensitive. The study provides a disturbed-state reference for monitoring effects of remedial actions begun in 1991, and for comparisons with other Colorado rivers. 相似文献
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6.
John R. Spence 《西北部美国博物学家》2011,65(1)
Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed. 相似文献
7.
Critical thermal maxima (CTM) and thermal preferenda of the common fishes of the Virgin River were examined. Differences in final temperature preferenda and CTM for species with low thermal lability (speckled dace, spinedace, roundtail chub) correspond well with differences in their distribution and abundance in the river. These species shifted their acute thermal preferences relatively little as acclimation temperature increased. For thermally labile species (woundfin, red shiner, desert sucker, and flannelmouth sucker), the final preferendum is a less precise indicator of probably distribution. The woundfin, an endangered fish, has a high CTM (39.5 C at 25 C acclimation) and a labile species preferendum (slope nearest 1) compared to other species in the system. The introduced red shiner likewise has a high CTM and a labile acute preferendum. In cooler temperatures, its acute preferendum shifts more rapidly than does that of the woundfin. At higher temperatures (above 15 C), the red shiner does not shift its acute preferendum as rapidly as does the woundfin. The red shiner, however, has a higher final preferendum. For thermally labile species, influence of acclimation temperature on mean preferendum, together with CTM, provides a better insight into distributional relationships within the system. 相似文献
8.
《Journal of Natural History》2012,46(12):1509-1528
An investigation was carried out over a five-year period into the blackfly fauna of one of the most important rivers of the North-Central European lowlands, the Oder, together with its major tributaries (Nysa, Stobrawa, O?awa, Barycz, Bobr, Kroisa, Lausitzer Neisse, Warta, Notec), from its source in the Oder Hills to its mouth in the Baltic Sea. Thirteen species were found. The two dominant indicator species, Simulium (Simulium) reptans (Linnaeus) and Simulium (Schoenbaueria) nigrum (Meigen), develop populations of plague proportions within this catchment area. Blackflies of the subgenus Schoenbaueria Enderlein have not been found in Germany or Poland for more than 70 years. However, since 1997, the species S. (Sch.) nigrum was found in the River Oder in enormous numbers together with S. (S.) reptans, and in the vicinity of their breeding sites in Poland and eastern Germany both species are serious pests of man and grazing animals. Notes are given on the biology, distribution and habitat preferences of S. (Sch.) nigrum. The paper concludes with a comparison of the River Oder with some other Central European rivers in respect of its blackfly fauna, together with data on the phenology of the two indicator species. 相似文献
9.
《Journal of Natural History》2012,46(15-16):1121-1128
Anadromous fish could have intraspecific groups with different life histories; identification of these is very important for management and conservation. Geometric morphometrics represents a quick and cost-effective method to identify such intraspecific groups. In this study, geometric morphometrics of Pontic shad (Alosa immaculata) migrants from the Danube River were investigated, as was Fulton's condition factor (K), hepatosomatic index (HSI) and gonadosomatic index (GSI). Pontic shad specimens were collected during April and May of 2004 and 2006. The sample comprised four groups (65 males and 56 females in 2004; 110 males and 78 females in 2006). Geometric morphometrics revealed differences in shape that were statistically significant for both year (nested analysis of variance: F = 13.84; p < 0.001) and sex (nested analysis of variance: sex nested in year, F = 1.71; p < 0.01). The major differences between years were in head shape and position of fins. The most significant difference between females and males was in the dorsolateral expansion of the mid-body section with emphasis on the higher dorsal part of the body. Values for K in this work (0.65–0.70) were the lowest recorded for Pontic shad in the Danube River. Additional investigations involving both geometric morphometrics and molecular genetics are necessary to confirm the presence of races. This could be important information for conservation purposes as Pontic shad is listed as Vulnerable on the International Union for Conservation of Nature list. 相似文献
10.
Gerald F. Shields Brooke A. Christiaens Michelle L. Van Leuven Amber L. Hartman 《西北部美国博物学家》2011,69(4)
We made 27 collections over nine years at the Clearwater River and conducted preliminary cytogenetic analysis on 232 individuals of the Simulium arcticum complex there. Based on these preliminary findings, we analyzed an additional 1825 larvae from Clearwater collections in 2007, 2008, and 2009 to investigate the reproductive statuses of the two prevalent taxa of the complex there and to determine whether cytogenetic diversity and frequency of types were similar from year to year. We describe a cytotype new to science and a potentially derivative cytotype of S. arcticum sensu stricto. We also determine that these two taxa are present in similar frequencies from year to year and are in genetic equilibrium, suggesting that they are not reproductively isolated. This study constitutes the fourth positive test of our Geographic Distribution/Taxon Age hypothesis. 相似文献
11.
Chironomidae (Diptera) of the Colorado River, Grand Canyon, Arizona, USA, I: systematics and ecology
We describe the chironomid midge fauna of the Colorado River between Glen Canyon Dam and Lake Mead, Arizona. This depauperate fauna, consisting of 38 species, is dominated by euryecious Nearctic or Holarctic orthocladine taxa. In addition, a small Neotropical faunal component is represented by Polypedilum obelos Sublette & Sasa and Rheotanytarsus hamatus Sublette & Sasa. The following new synonyms are given: Protenthes riparius Malloch 1915 with Tanypus bellus Loew 1866 [= Procladius (Psilotanypus) bellus (Loew)]; Cricotopus olivetus Boesel 1983 with Cricotopus (Circotopus) annulator (Goetghebuer) 1927; Cricotopus edurus Sublette & Sublette 1971 with Orthocladius infuscatus Malloch 1915 [= Cricotopus (Cricotopus) infuscatus (Malloch)]. The following new species are described: Cricotopus (Cricotopus) blinni Sublette, Cricotopus (Cricotopus) hermanni Sublette, Metriocnemus stevensi Sublette, and Cladotanytarsus marki Sublette. We discuss the distribution and ecology of each chironomid species in this large, regulated, aridlands river. 相似文献
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《Journal of Natural History》2012,46(45-46):2875-2897
ABSTRACTA new species of crayfish, Cambarus loughmani sp. nov., is described from the preglacial Teays River Valley of Cabell, Kanawha, Lincoln, Mason, and Putnam counties, West Virginia. The species was previously considered to be part of the Cambarus dubius complex. Loughman et al. restricted C. dubius to an orange colour morph found in central and northern portions of the Allegheny Mountains and Appalachian Plateau in central West Virginia, western Maryland, and south-central Pennsylvania. The new species described herein can be distinguished from all other members of Cambarus Erichson, 1846 by a double row of cristiform tubercles on the palm, an open areola with two rows of punctations, and a consistent blue colouration.http://www.zoobank.org/urn:lsid:zoobank.org:pub:5BC7C861-038E-457C-80F3-ED7A66E10D73 相似文献
14.
Streambed surveys were conducted along the upper Colorado River, Colorado, to describe the distributions of Claassenia sabulosa larvae in relation to current speed and to determine their diets. We also addressed diel feeding periodicity by sampling during both day and night. Claassenia sabulosa was more abundant in riffle habitats than in runs. A positive relationship existed between C. sabulosa abundance and stream current, with larval size increasing with current speed. Chironomidae, Baetidae, and Simulidae collectively accounted for 93% of the prey found in stonefly guts; however, these categories were not consumed equally by all C. sabulosa . Smaller C. sabulosa primarily ate chironomids, and larger individuals consumed more baetids. Only a slight difference existed in the percentage of empty guts between night- and day-collected stoneflies, and ranges of prey per gut at night were higher than those in the day, suggesting that these stoneflies may forage more intensively at night. 相似文献
15.
Arctomecon humilis Cov. is a narrow endemic, confined to gypsiferous substrates derived from the Shnabkaib Member of the Moenkopi Formation in southwestern Utah. The characteristics of seven A. humilis sites were studied to define habitat requirements of the species. Both physical and biotic aspects of the habitat were analyzed; geology, soil chemistry, and physical properties, as well as vascular and nonvascular plant communities, were studied. Chemical and physical properties of these soils vary considerably from those supporting adjacent desert-shrub communities. The dominant vascular species on A. humilis sites are shadscale and Mormon tea. It was found that A. humilis occurred in portions of the habitat where shrubs were relatively less dense. A soil-surface, cryptogamic community contributed 84% or more of the total living cover on sites that supported A. humilis . Species composition of the cryptogamic community was highly similar among sites. Likewise, composition of the cryptogamic cover was similar when random samples were compared with samples centered on A. humilis plants. The Purgatory Flat site, which does not support the poppy, seems inseparable from A. humilis sites, in respect to soil characteristics and composition of the associated plant cover. There is reason to believe an A. humilis population could be established at the Purgatory Flat site. 相似文献
16.
We studied the breeding system and flower visitors of White River penstemon, a rare endemic from the Uintah Basin of eastern Utah and western Colorado. Bagging treatments and hand-pollination treatments showed that Penstemon scariosus var. albifluvis has a mixed mating system: while some seeds and fruits are produced through selfpollination (both autogamy and geitonogamy), significantly more are produced when flowers are cross-pollinated. The primary flower visitors, and likely pollinators, were several species of native twig- and ground-nesting bees in the families Apidae, Halictidae, and Megachilidae. We found no differences in fruit or seed production between open-pollinated controls and hand-outcrossed flowers, suggesting that pollinator visits were sufficient to maximize female reproductive success. Management plans to conserve White River penstemon must recognize that full reproductive success of this rare plant taxon relies on a suite of pollinating bees, and that the species richness and abundances of bee visitors should be maintained. 相似文献
17.
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Peromyscus maniculatus and related small rodents have been examined for ectoparasites in the tundra region of the Rocky Mountain National Park 1974–1979. One hundred and ninety-four P. maniculatus were examined from two tundra sites. Flea infestation rates were 1.9 fleas per mouse examined and 4.1 fleas per infested mouse. Species taken in significant numbers were Monopsyllus thambus (51 percent), Peromyscopsylla hesperomys (34 percent), Malaraeus euphorbi (9 percent), and Catallagia calisheri (4 percent). Peromyscus maniculatus host/flea relationships in the tundra are compared with those in other life zones in the park. 相似文献
18.
《Journal of Natural History》2012,46(41-42):2595-2608
Box jellyfishes (Cnidaria: Cubozoa) have a profound impact on human activities because of their highly potent venoms that may lead to severe envenomations in humans. Cubozoa is one of the smallest classes within Cnidaria with only some 50 described species in seven families. The literature on Cubozoa is scattered and oftentimes difficult to access. In particular, comprehensive treatments of Cubozoa that present a comparative overview of the group are either non-existent or largely outdated. Here we provide a synopsis of the carybdeid Cubozoa (Carybdeida) including an illustrated key to the families and genera of this order. Of particular interest is the family Carukiidae, which contains the species that was originally attributed with causing a severe envenomation syndrome called Irukandji syndrome. One new species of Carukiidae, Malo filipina sp. nov., is described, Morbakka virulenta is redescribed and a neotype is designated, and an unidentified species of Morbakka is recorded from the Philippines. 相似文献
19.
The milliped genus Apheloria occupies a broad area in Québec and Ontario, Canada, and the United States east of the Central Plains, lying generally north of the Gulf Coastal states. It is reported for the 1st time from New Jersey, District of Columbia, Illinois, and Kansas; and the 1st localities are recorded for Massachusetts, Connecticut, South Carolina, Georgia, Alabama, and Wisconsin. The projected distribution encompasses all or parts of the District of Columbia and 27 states, including Vermont and Delaware, where the genus has not been taken; New Hampshire and Mississippi lie outside the range. Chesapeake Bay and the Connecticut River form apparent eastern boundaries in Maryland–Virginia and New England, respectively; the Tennessee River does likewise on the south in northern Alabama. Aside from Arkansas, comparatively few records exist from the 6 projected states of occurrence west of the Mississippi River. Only 1 each is available from Iowa and Kansas, and there are no definite localities in Nebraska, where occurrence is postulated at Omaha, the type locality of Fontaria luminosa Kenyon, 1893. Confirmation with fresh material is necessary, but this name seems referrable to Apheloria and may be senior to either A. virginiensis iowa or A. v. reducta , both by Chamberlin, 1939, if 2 distinct races occur west of the Mississippi River. 相似文献
20.
Twelve wild adult Colorado pikeminnow ( Ptychocheilus lucius ), captured in the tailwaters of Taylor Draw Dam on the White River, Colorado, were implanted with radio transmitters and their movement patterns monitored from 1992 to 1994. The spawning migration of these fish was extensive. In 1993, the only full year of the study, the fish migrated an average of 658 km from the White River to spawning sites in the Yampa or Green rivers and back to the White River. Eight of these fish were translocated in the river upstream of the dam in April 1993. These fish and the 4 others below the dam remained in the river until May 1993. All 12 had migrated down the White River to spawning sites in the Green and Yampa rivers by July 1993. The fish that were located above the dam successfully passed over the dam during their downstream migration. Seven fish migrated upstream toward the Yampa River Canyon spawning site and 5 migrated downstream toward the Green River Desolation/Gray Canyon spawning site. Five of 7 Yampa River fish were found at the spawning site. The other 2 were found 5-8 km downstream of the site. One of 5 Green River fish was found at the spawning site, the other 4 between 16 and 62 km upstream of the site. All fish migrated back to the White River by August 1993 and were found near the dam by October 1993. Two fish were recaptured and translocated above the dam in September 1993. Five fish were located below the dam and 2 above the dam in April 1994. By July 1994 seven of the same fish that had migrated toward the Yampa River in 1993 were found at the Yampa Canyon spawning site. At the same time, 3 of 5 fish that migrated toward the Green River in 1993 were found at the Desolation/Gray Canyon spawning site. This included 2 fish that had been found upstream of the site in 1993. The 12 fish traveled an average of 6 km d -1 (range: 4-10 km d -1 ) during the migration period from May through October 1993. Generally, fish moved faster to the spawning site than back from the site to the White River. These fish moved very little within their home ranges in the White River. Six fish tagged in 1992 moved only 0.1-2.3 km in the tailwater reach below Taylor Draw Dam from September 1992 through April 1993. All fish, after their spawning runs, had moved up to or near the dam by October 1993. These fish were not tracked again until April 1994. Their movement patterns in April 1994 were similar to those observed in April 1993. The greatest amount of fish movement in the White River was displayed by the 8 fish placed above Taylor Draw Dam in April 1993 and the 2 placed in Kenney Reservoir in September 1993. They moved 1.1-40.6 km in the river before and after their spawning migration in spring and autumn 1993. These spawning migrations suggest that adult Colorado pikeminnow in the White River were recruited from both Green and Yampa river spawning populations and were presumably imprinted to these respective spawning sites. Those fish placed above Taylor Draw Dam established home ranges in habitats previously occupied by Colorado pikeminnow before the dam was completed. They remained there until they migrated downstream during the spawning period. Although we did not study fish passage, our study demonstrates that adult Colorado pikeminnow will use habitat if access is provided. Translocation of wild adult fish into historic but unoccupied habitats may be a valuable recovery option. 相似文献