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Articles 181 - 210 of 220

Full-Text Articles in Life Sciences

Proximate Constraints On Intruder Detection In The Dragonfly Perithemis Tenera (Odonata: Libellulidae): Effects Of Angle Of Approach And Background, Paul V. Switzer, Perri K. Eason Jan 2000

Proximate Constraints On Intruder Detection In The Dragonfly Perithemis Tenera (Odonata: Libellulidae): Effects Of Angle Of Approach And Background, Paul V. Switzer, Perri K. Eason

Paul V. Switzer

The implications of insects’ vision for territorial defense have been relatively little studied in the field. In the dragonfly Perithemis tenera Say we investigated whether either the angle at which an intruder was viewed by a territorial resident or the background against which it was viewed affected the detection of that intruder. Residents detected intruders at a greater distance if the intruders were directly in front of them; they also detected more intruders in front of them than from other angles. Intruders viewed against distant vegetation were detected more readily than were intruders against near vegetation. Residents detected more intruders …


Access To Another Mind: Naturalistic Theories Require Naturalistic Data, Mark A. Krause, Gordon Burghardt Dec 1999

Access To Another Mind: Naturalistic Theories Require Naturalistic Data, Mark A. Krause, Gordon Burghardt

Gordon Burghardt

If there is to be a natural theory of consciousness that would satisfy both philosophers and scientists, it must be based on naturalistic data and minimal clutter accumulated from semantic arguments. Carruthers offers a 'natural' theory of consciousness that is rather myopic. To explore the evolutionary basis of consciousness, a natural theory should include comparative psychological and neurological data that encompass nonlinguistic measures. Such an approach could provide a clearer picture of the adaptive function, mechanisms, and origins of consciousness.


Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin Mar 1999

Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin

Brian S Dorr

No abstract provided.


Revegetating Desert Plant Communities, David A. Bainbridge Jan 1999

Revegetating Desert Plant Communities, David A. Bainbridge

David A Bainbridge

Desert revegetation is possible but not easy. Careful attention to plant production (root:shoot), site prep, planting, irrigation and aftercare can lead to good survival even under extreme desert conditions. Cost per survivor is a critical consideration.


Soil Pitting For Revegetation, David A. Bainbridge Jan 1999

Soil Pitting For Revegetation, David A. Bainbridge

David A Bainbridge

Soil pitting provides many benefits in ecological restoration of degraded lands. The pits capture rainwater, trap seeds and soil symbionts and protect seedlings from windblast.


Soil Treatment For Restoration Projects, David A. Bainbridge Jan 1999

Soil Treatment For Restoration Projects, David A. Bainbridge

David A Bainbridge

Soil treatment is a critical step in restoration projects. When soil problems are ignored restoration projects fail. Erosion, compaction, limited infiltration and other problems can make a site very different from its historic function and structure. Treatment can be done with equipment or by hand and will greatly improve chances for success.


Soil Amino Acid Utilization Among Species Of The Cyperaceae: Plant And Soil Processes, Ted K. Raab, David A. Lipson, Steven K. Scmidt, Russ K. Monson Jan 1999

Soil Amino Acid Utilization Among Species Of The Cyperaceae: Plant And Soil Processes, Ted K. Raab, David A. Lipson, Steven K. Scmidt, Russ K. Monson

Ted K. Raab

Amino acids are released during the decomposition of soil organic matter and have been shown to be utilized as a nitrogen source by some non-mycorrhizal species in the family Cyperaceae (the sedge family). Twelve out of 13 Cyperaceae species examined in the current study were capable of absorbing soil amino acids in the non-mycorrhizal state. With two exceptions (two species in the genus Kobresia), species from subalpine or alpine habitats exhibited lower rates of total nitrogen uptake compared to species from more temperate habitats, which is possibly explained by lower growth rates in the alpine and subalpine species and a …


Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson Jan 1999

Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson

Ted K. Raab

Microbes are assumed to possess strong competitive advantages over plants for uptake of nutrients from the soil. The finding that non-mycorrhizal plants can obtain a significant fraction of their N requirement from soil amino acids contradicts this assumption. The amino acid glycine (Gly) has been used as a model amino acid in many recent studies. Our preliminary studies showed that Gly was a poor substrate for microbial growth compared to other amino acids. We tested the hypothesis that the alpine sedge Kobresia myosuroides competes better for Gly than for other amino acids because of decreased microbial demand for this compound. …


Avian Prey-Dropping Behavior. I. The Effects Of Prey Characteristics And Prey Loss, Paul V. Switzer, Daniel A. Cristol Jan 1999

Avian Prey-Dropping Behavior. I. The Effects Of Prey Characteristics And Prey Loss, Paul V. Switzer, Daniel A. Cristol

Paul V. Switzer

No abstract provided.


Evaluation Of A Methyl Anthranilate-Based Bird Repellent: Toxicity To Channel Catfish Ictalurus Punctatus And Effect On Great Blue Heron Ardea Herodias Feeding Behavior, Brian S. Dorr, Larry Clark, Igor Mezine Dec 1998

Evaluation Of A Methyl Anthranilate-Based Bird Repellent: Toxicity To Channel Catfish Ictalurus Punctatus And Effect On Great Blue Heron Ardea Herodias Feeding Behavior, Brian S. Dorr, Larry Clark, Igor Mezine

Brian S Dorr

No abstract provided.


Improving Recovery Planning For Threatened And Endangered Species, Theodore C. Foin, Seth P. Riley, Anitra L. Pawley, Debra R. Ayres, Tina M. Carlsen, Peter J. Hodum, Paul V. Switzer Jan 1998

Improving Recovery Planning For Threatened And Endangered Species, Theodore C. Foin, Seth P. Riley, Anitra L. Pawley, Debra R. Ayres, Tina M. Carlsen, Peter J. Hodum, Paul V. Switzer

Paul V. Switzer

No abstract provided.


Evolutionary Genetics And Genetic Variation Of Haplodiploids And X-Linked Genes, Philip W. Hedrick, Joel D. Parker Nov 1997

Evolutionary Genetics And Genetic Variation Of Haplodiploids And X-Linked Genes, Philip W. Hedrick, Joel D. Parker

Joel D Parker

The evolutionary genetics of haplodiploids and X-linked genes share many features and are different from diploid (autosomal) genes in many respects. For example, the conditions for a stable polymorphism, the amount of genetic load, and the effective population size are all expected to be quite different between haplodiploids or X-linked genes and diploids. From experimental data, the genetic load for X-linked genes is much less than autosomal genes and appears less for haplodiploids than for diploids. The observed amount of molecular variation for haplodiploids is much less than that for diploids, even more so than predicted from the differences in …


Crows Do Not Use Automobiles As Nutcrackers: Putting An Oft-Repeated Anecdote To The Test, Daniel A. Cristol, Paul V. Switzer, K L. Johnson, L S. Walke Jan 1997

Crows Do Not Use Automobiles As Nutcrackers: Putting An Oft-Repeated Anecdote To The Test, Daniel A. Cristol, Paul V. Switzer, K L. Johnson, L S. Walke

Paul V. Switzer

No abstract provided.


Pollen Dispersal In Low-Density Populations Of Three Neotropical Tree Species, Jason D. Nason, E. A. Stacy, J. L. Hamrick, S. P. Hubbell, R. B. Foster, R. Condit Aug 1996

Pollen Dispersal In Low-Density Populations Of Three Neotropical Tree Species, Jason D. Nason, E. A. Stacy, J. L. Hamrick, S. P. Hubbell, R. B. Foster, R. Condit

Jason D Nason

Studies of mating patterns of tropical trees, typically involving common species, have revealed that most species are outcrossed and that, in some cases, a significant reaction of outcross pollen moves long distances. We evaluated mating systems and effective pollen dispersal for three hermaphroditic insect-pollinated Neotropical tree species, Calophyllum longifolium, Spondias mombin and Turpinia occidentalis, all of which occurred at low adult densities at the study site. Mating patterns were estimated for each maternal tree within 84-ha populations of C. Longifoliuman d S. mombin in 1992 and 1993 and within a 50-ha population of T. occidentalis in 1993. Each population was …


Bird Aversive Properties Of Methyl Anthranilate, Yucca, Xanthoxylum, And Their Mixtures, Larry Clark, Bruce Bryant, Igor Mezine Jan 1996

Bird Aversive Properties Of Methyl Anthranilate, Yucca, Xanthoxylum, And Their Mixtures, Larry Clark, Bruce Bryant, Igor Mezine

Larry Clark

We tested the bird aversive properties of methyl anthranilate, yucca extracts, and Xanthoxylum spp. extracts in one- and two-bottle drinking assays that used European starlings (Sturnus vulgaris). In one- and two-bottle tests, methyl anthranilate proved to be the more potent stimulus in producing an avoidance response. Starlings avoided consuming Xanthoxylum and yucca only in the two-bottle tests. Previous studies showed that yucca was a good adjuvant in stabilizing lipophilic compounds in water. Starlings did not avoid binary mixtures of methyl anthranilate and yucca differently from what would be expected if they were only responding to the solution's methyl anthranilate content. …


Grazing Repellency Of Methyl Anthranilate To Snow Geese Is Enhanced By A Visual Cue, J. Russell Mason, Larry Clark Jan 1996

Grazing Repellency Of Methyl Anthranilate To Snow Geese Is Enhanced By A Visual Cue, J. Russell Mason, Larry Clark

Larry Clark

Methyl anthranilate (Rejex-It AG-36) is formulated as a commercial goose repellent. Frequent reapplications of this product are often necessary, and the cost/application is high ($300.00/ha). The present experiment tested the possibility that the repellency of methyl anthranilate might be enhanced by the addition of visual cues. Twelve 0.4 ha plots were assigned randomly to three treatment groups. Plots in the first group (n = 4) were sprayed with 10% Vapor Guard (an agrochemical adhesive). Plots in the second group (n = 4) were treated with a mixture of methyl anthranilate (3.4 kg/ha) and Vapor Guard. Plots in the third group …


Avoidance Of Cabbage Fields By Snow Geese, J. Russell Mason, Larry Clark Jan 1996

Avoidance Of Cabbage Fields By Snow Geese, J. Russell Mason, Larry Clark

Larry Clark

now Goose activity levels were significantly less in cabbage fields than in control fields. Although the data do not unambiguously address the issue of sulfur repellency, we believe that the activity difference is consistent with avoidance of the former and not preference for the latter. Sulfurous volatiles were readily apparent to us during our visits to cabbage fields throughout the study period. Similar odors were not detected in control fields. If sulfurous volatiles were important, then avoidance could reflect some characteristic of the cover crop (e.g., unpalatability acquired through the absorption and translocation of degra­ dation products) or it could …


Non-Mycorrhizal Uptake Of Amino Acids By Roots Of The Alpine Sedge Kobresia Myosuroides: Implications For The Alpine Nitrogen Cycle, Ted K. Raab, David A. Lipson, Russ K. Monson Jan 1996

Non-Mycorrhizal Uptake Of Amino Acids By Roots Of The Alpine Sedge Kobresia Myosuroides: Implications For The Alpine Nitrogen Cycle, Ted K. Raab, David A. Lipson, Russ K. Monson

Ted K. Raab

Non-mycorrhizal plants of the alpine sedge, Kobresia myosuroides , take up the amino acid glycine from nutrient solutions at greater rates than NO3- or NH4+. The amino acids glutamate and proline were also taken up at high rates. Total plant biomass was twice as high after 4 months of growth on glycine, compared to NH4NO3, with significant increases in both root and leaf biomass. By taking advantage of differences in the d13C signature of air in the growth chamber and the glycine used for growth, a two-member mixing model was used to estimate that a significant amount of the glycine …


Interactions Between Predation Risk And Competition - A Field-Study Of Kangaroo Rats And Snakes, Amos Bouskila Jan 1995

Interactions Between Predation Risk And Competition - A Field-Study Of Kangaroo Rats And Snakes, Amos Bouskila

Amos Bouskila

The effects of predation risk from snakes on microhabitat use of kangaroo rats (Dipodomys deserti and D. merriami) was studied in the Mojave Desert. I concentrated on the effects of the predator on the foraging behavior of the rodents and eliminated effects of prey capture on prey population size. Foraging stations contained three seed trays, one in each of three microhabitats (Open, Bush, Grass). The amount of seed left in each tray after one night of foraging was used to assess the responses to predation risk and other foraging costs; additional data were collected during direct observations and by trapping. …


The Hazardous Waste Land, Jerry L. Anderson Nov 1993

The Hazardous Waste Land, Jerry L. Anderson

Jerry L. Anderson

This article was one of the first comprehensive critiques of the Superfund remediation and liability system. The article addresses systemic problems with the CERCLA mechanism that result in inequity and slow the pace of cleanups.


Functional Explanation And Metaphysical Individualism, Justin Schwartz Jan 1993

Functional Explanation And Metaphysical Individualism, Justin Schwartz

Justin Schwartz

A number of (present or former) analytical Marxists, such as Jon Elster, have argued that functional explanation has almost no place in the social sciences. (Although the discussion is framed in terms of a debate among analytical Marxists, the point is quite general, and Marxism is used for illustrative purposes.) Functional explanation accounts for what is to be explained by reference to its function; thus, sighted organism have eyes because eyes enable them to see. Elster and other critics of functional explanation argue that this pattern of explanation is inconsistent with "methodological individualism," the idea, as they understand it, that …


White Plastic Flags Repel Snow Geese, J. Russell Mason, Larry Clark, N. Jay Bean Jan 1993

White Plastic Flags Repel Snow Geese, J. Russell Mason, Larry Clark, N. Jay Bean

Larry Clark

The effectiveness of white flags as visual repellents to snow geese (Chen caerulescens) was evaluated. Twelve fields, each 10.12 ha (25 acres) in area, with snow goose damage, were located and proximity was used to create six pairs. Within each pair, one field was selected randomly for treatment (one white plastic flag per acre) and the other served as a control. At 7-day intervals for SV2 weeks, mean vegetation length and mean percentage vegetative cover were estimated for all fields. The results showed that grazing damage was significantly reduced in fields with flags. It is concluded that white plastic flags …


Development Of Chemosensory Attractants For White-Tailed Deer (Odocoileus Virginianus), J. Russell Mason, N. Jay Bean, Larry Clark Jan 1993

Development Of Chemosensory Attractants For White-Tailed Deer (Odocoileus Virginianus), J. Russell Mason, N. Jay Bean, Larry Clark

Larry Clark

White-tailed deer (Odocoileus spp.) overpopulate many areas of the United States. Browse damage to agricultural crops, forest regeneration and landscaping can be severe. Human and animal health also arc threatened by Lyme disease, which is spread by the deer tick (Ixodes dammini). Although sterilants to reduce and/or slow the growth of deer populations and vaccines against Lyme disease may soon become available, efficient and economical techniques to inoculate large numbers of deer have not been developed. Oral baits represent one promising possibility. In experiment 1, salt blocks and several olfactory lures were evaluated as potential lures for use in deer …


Capsaicin Effects On Consumption Of Food By Cedar Waxwings And House Finches.­, Donald Norman, Russell Mason, Larry Clark Jan 1992

Capsaicin Effects On Consumption Of Food By Cedar Waxwings And House Finches.­, Donald Norman, Russell Mason, Larry Clark

Larry Clark

Capsaicin effects on consumption of food by Cedar Waxwings and House Finches.­ Capsaicinoids (e.g., N-vanillyl-n-nonamide. norcapsaicin, nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, homodihydrocapsaicin; Hoffman 1983) are aromatic am­ ides and the pungent principles in Capsicum peppers. Although these substances are strong chemical irritants for most mammals (e.g.. Rozin et a!. 1979), the available data suggest that they are inoffensive to some birds. For example. European Starlings (Sturn us vulgaris) and Rock Doves (Columba Iivia) are unresponsive to these compounds, even when con­ centrations greatly exceed those which mammals avoid (Szolcsanyi et al. 1986; Mason et a!.. in press).


Taxonomic Differences Between Birds And Mammals In Their Responses To Chemical Irritants, Russell Mason, Larry Clark, Pankaj Shah Jan 1992

Taxonomic Differences Between Birds And Mammals In Their Responses To Chemical Irritants, Russell Mason, Larry Clark, Pankaj Shah

Larry Clark

Ninety-five products are registered with the u.s. Environmental Pro­ tection Agency as bird damage control chemicals, but 38 (40%) are non­ lethal chemical repellents (Eschen and Schafer, 1986). Of these products, the active ingredients in 27 (71%) are methiocarb (a physiologic repellent that acts through food avoidance learning) or polybutene (a tactile repel­ lent). In general, chemical repellents are effective either because of aversive sensory effects (irritation), or because of post-ingestional ma­ laise (sickness). If the former, then chemicals are usually stimulants of trigeminal pain receptors (i.e., undifferentiated free nerve endings) in the nose, mouth, and eyes (Mason and Otis, …


Reproductive Compatibility Of New World Screwworms, Cochliomyia Hominivorax, From North Africa And Central America., David B. Taylor, Leslie Hammack, Richard L. Roehrdanz Jan 1991

Reproductive Compatibility Of New World Screwworms, Cochliomyia Hominivorax, From North Africa And Central America., David B. Taylor, Leslie Hammack, Richard L. Roehrdanz

David B Taylor

The reproductive compatibility of New World screwworms, Cochliomyia hominivorax (Coquerel), from North Africa and a strain being mass produced for the Mexican eradication programme was examined to assess the feasibility of using flies from the Mexican screwworm mass production facility for a sterile insect technique eradication programme in North Africa. Males from the production strain mated randomly with females from North Africa and from the production strain when both were present. Neither strain of males discriminated between cuticular extracts of North African and production strain females containing a contact sex pheromone. Interstrain crosses between North African flies and production flies …


Genetics Of Screwworm, New Genetic Markers And Preliminary Linkage Map., David B. Taylor Jan 1989

Genetics Of Screwworm, New Genetic Markers And Preliminary Linkage Map., David B. Taylor

David B Taylor

Eight new genetic markers for Cochliomyia hominivorax (Diptera: Calliphoridae), the screwworm, are characterized. The markers include three eye mutants, lemon-eye (le), cherry-eye (ch), and red-eye (re); one wing mutant, curly-wing (cw); and four allozyme markers, amylase (Amy-1), glycerol-3-phosphate dehydrogenase (Gpd), phosphoglucomutase (Pgm), and octanol dehydrogenase (Odh). The markers are associated into four linkage groups. Radiation-induced translocations were used to correlate the linkage groups with their respective chromosomes. A preliminary genetic linkage map with these and three previously characterized loci is presented.


A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark Jan 1988

A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark

Larry Clark

We develop a simple single dimension model incorporating the time and energy commitments of breeding altricial birds in an effort to understand the evolutionary constraints on parental care. We chose time as the dimension of preference, because it is a naturally bounded constraint, e.g., length of day or breeding season. The utility of the model was evaluated by comparing simulations of time allocation of various breeding scenarios for the European starling (Sturnus vulgaris) to field data. The structure of the model may prove useful in determining the evolutionary constraints on parental care imposed by the developmental pattern of chicks.


Truncation Of Screwworm (Diptera: Calliphoridae) Development By Irradiation Of Embryos., David B. Taylor, Robert L. Mangan Jan 1988

Truncation Of Screwworm (Diptera: Calliphoridae) Development By Irradiation Of Embryos., David B. Taylor, Robert L. Mangan

David B Taylor

Gamma irradiation of screwworm, Cochliomyia hominivorax (Coquerel), embryos was used to truncate the life cycle at the prepupal stage. Egg hatch and larval survival were not reduced by dosages ≤8 kilorads (kr). Pupariation and adult emergence were inhibited by dosages ≥2.8 and 1.2 kr, respectively. Larvae, irradiated as embryos with dosages ≤8 kr, successfully infested wounded sheep, although larval weight was lower than normal. A dosage of 5.8 kr was sufficient to prevent pupariation, while permitting larval development to the third instar. Truncation of screwworm development permits the use of artificially wounded and infested animals for screwworm population surveillance and …


Thermal Constraints On Foraging Activity Of Adult Starlings, Larry Clark Jan 1987

Thermal Constraints On Foraging Activity Of Adult Starlings, Larry Clark

Larry Clark

The operative temperature of the environment was estimated for starlings using hollow, unheated taxidermic mounts. On average, adults foraging in full sun were characterized by shorter foraging bouts than those adults foraging in full shade. Simultaneous observations of air temperature, operative temperature, and the foraging duration of adults indicated that air temperature was a poor predictor of the maximum length of a foraging bout. The operative temperature of the environment was not correlated to the maximum and mean length of foraging bouts for temperatures below 31.5 ~ C, but was negatively related to maximum and mean foraging duration for values …