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Articles 241 - 265 of 265
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Modeling Viable Mammal Populations In Gap Analyses, Craig R. Allen, L. G. Pearlstine
Modeling Viable Mammal Populations In Gap Analyses, Craig R. Allen, L. G. Pearlstine
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Gap analysis is an approach to conserving biological diversity that maps species richness and identifies sites that ought to be protected but are not in conservation networks. Gap analyses based on species richness may have high error rates when species models are based solely on species-habitat association, because patches too small to support populations are still considered to be potential habitat. We incorporated information on the home range and dispersal distances of the mammals of Florida to estimate minimum critical areas (MCA) to support minimum viable populations for each mammal species. Incorporating MCA decreases the area occupied by the highest …
Potential Fire Ant (Hymenoptera: Formicidae) Impact On The Endangered Schaus Swallowtail (Lepidoptera: Papilionidae), Elizabeth A. Forys, Anna Quistorff, Craig R. Allen
Potential Fire Ant (Hymenoptera: Formicidae) Impact On The Endangered Schaus Swallowtail (Lepidoptera: Papilionidae), Elizabeth A. Forys, Anna Quistorff, Craig R. Allen
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
The Schaus swallowtail, Papilio aristodemus ponceanus, historically occurred in tropical hardwood hammocks from South Miami to the upper Florida Keys and is currently listed as federally endangered. Much of the remaining hardwood hammock habitat is fragmented by roads and human development that may alter the microhabitat within the hammocks and increase the probability of invasion by non-native predators and competitors. One non-indigenous species that has recently invaded the Florida Keys, and that may impact the Schaus swallowtail is the red imported fire ant (Solenopsis invicta Buren). We estimated abundance of red imported fire ants in Schaus swallowtail habitat …
The Spatial Distribution Of Diversity Between Disparate Taxa: Spatial Correspondence Between Mammals And Ants Across South Florida, Usa, Craig R. Allen, L. G. Pearlstine, D.P. Wojcik, W.M. Kitchens
The Spatial Distribution Of Diversity Between Disparate Taxa: Spatial Correspondence Between Mammals And Ants Across South Florida, Usa, Craig R. Allen, L. G. Pearlstine, D.P. Wojcik, W.M. Kitchens
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Gap Analysis takes a proactive landscape-level approach to conserving native species by identifying nodes of high biological diversity. It uses vertebrate species richness as an index of overall biological diversity. However, it remains unknownwhether or not the spatial distribution of vertebrate diversity correspondswith the diversity of other taxa. We tested whether landscape-level diversity patterns corresponded between a vertebrate and an invertebrate taxon, mammals and ants, across the southern half of the Florida peninsula, USA. Composite digital maps with a 30-m spatial resolution were produced for each taxon. Spatial correspondence between the taxa was determined by normalizing and then subtracting the …
Parental Care And Clutch Sizes In North And South American Birds, Thomas E. Martin, P. R. Martin, C. R. Olson, B. J. Heidinger, J. J. Fontaine
Parental Care And Clutch Sizes In North And South American Birds, Thomas E. Martin, P. R. Martin, C. R. Olson, B. J. Heidinger, J. J. Fontaine
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
The evolutionary causes of small clutch sizes in tropical and Southern Hemisphere regions are poorly understood. Alexander Skutch proposed 50 years ago that higher nest predation in the south constrains the rate at which parent birds can deliver food to young and thereby constrains clutch size by limiting the number of young that parents can feed. This hypothesis for explaining differences in clutch size and parental behaviors between latitudes has remained untested. Here, a detailed study of bird species in Arizona and Argentina shows that Skutch's hypothesis explains clutch size variation within North and South America. However, neither Skutch's hypothesis …
Shrinkage Of Inland Silverside Larvae Preserved In Ethanol And Formalin, Mandy K. Cunningham, William F. Granberry, Kevin L. Pope
Shrinkage Of Inland Silverside Larvae Preserved In Ethanol And Formalin, Mandy K. Cunningham, William F. Granberry, Kevin L. Pope
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Length measurements of preserved larval fish are necessary in many types of larval fish surveys. If the fixative causes significant shrinkage, then the preserved lengths cannot be used to indicate accurate live lengths. The objective of this study was to determine how preservation in two different concentrations of formalin and ethanol affects the total length of larval inland silversides Menidia beryllina. Larvae were measured (nearest 0.1 mm) and individually fixed in one of four fixative treatments (80% ethanol, 100% ethanol, 5% buffered formalin, and 10% buffered formalin). Fish were remeasured (nearest 0.1 mm) at 15 min; 4 h; and …
Intermediate Rings Between A Local Domain And Its Completion, William Heinzer, Christel Rotthaus, Sylvia Wiegand
Intermediate Rings Between A Local Domain And Its Completion, William Heinzer, Christel Rotthaus, Sylvia Wiegand
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
We consider the structure of certain intermediate domains between a local Noetherian domain Rand an ideal-adic completion R* of R that arise as the intersection of R* with a field containing R. In the case where the intersection domain A can be expressed as a directed union of localized polynomial extension rings of R, the computation of A is easier. We examine conditions for this to happen. We also present examples to motivate and illustrate the concepts considered.
Development And Evaluation Of A Standard Weight (WS) Equation For Blue Catfish, Maurice I. Muoneke, Kevin L. Pope
Development And Evaluation Of A Standard Weight (WS) Equation For Blue Catfish, Maurice I. Muoneke, Kevin L. Pope
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Using a data set composed of 33 populations from six states, we employed the regression-linepercentile technique to develop a standard weight equation for blue catfish Ictalurus furcatus and validated it with an independent data set composed of 43 populations from 10 states. The equation is log10Ws=-6.067+ 3.400 log10TL, where Ws is standard weight in grams and TL is total length in millimeters. The English-unit equivalent (pounds and inches) is log10Ws=-3.950+ 3.400 log10TL. The equation is valid for blue catfish 160 mm (approximately 6 in) TL and longer. …
Body Mass Patterns Predict Invasions And Extinctions In Transforming Landscapes, Craig R. Allen, Elizabeth A. Forys, C. S. Holling
Body Mass Patterns Predict Invasions And Extinctions In Transforming Landscapes, Craig R. Allen, Elizabeth A. Forys, C. S. Holling
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Scale-specific patterns of resource distribution on landscapes entrain attributes of resident animal communities such that species body-mass distributions are organized into distinct aggregations. Species within each aggregation respond to resources over the same range of scale. This discontinuous pattern has predictive power: invasive species and extinct or declining species in landscapes subject to human transformation tend to be located at the edge of body-mass aggregations (P < 0.01), which may be transition zones between distinct ranges of scale. Location at scale breaks affords species great opportunity, but also potential crisis.
Larval Black Crappie Distribution: Implications For Sampling Impoundments And Natural Lakes, Kevin L. Pope, David W. Willis
Larval Black Crappie Distribution: Implications For Sampling Impoundments And Natural Lakes, Kevin L. Pope, David W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
An understanding of larval fish distributions is essential for developing an appropriate sampling design to monitor larval abundances. We monitored abundance of larval black crappie Pomoxis nigromaculatus to assess spatial differences in Richmond Lake (a 336-ha impoundment) and Brant Lake (a 405-ha natural lake), South Dakota, during 1994–1996. Age-0 black crappies were collected with a 500-µm mesh ichthyoplankton trawl from fixed sites within each water body. In the impoundment, larval black crappies were collected over a longer period at the upper site than at the dam site during 1994 and 1995. In the natural lake, larval black crappie abundances were …
Earlj Life Historj And Recruitment Of Black Crappie (Pomoxis Nigromaculatus) In Two South Dakota Waters, K. L. Pope, D. W. Willis
Earlj Life Historj And Recruitment Of Black Crappie (Pomoxis Nigromaculatus) In Two South Dakota Waters, K. L. Pope, D. W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
We compared the early life history of black crappie (Pomoxis nigromaculatus) in Richmond (an impoundment) and Brant (a natural lake) lakes during 1994-1996. We expected variable recruitment (i.e., missing year classes) in the natural lake and more consistent recruitment in the impoundment. Larval black crappie abundance was always higher in Richmond Lake than Brant Lake. Peak abundance of larval black crappie was highest during 1994 in both waters. However, peak larval abundance did not correspond with fall trap-net catch per unit effort (CPUE) of age-0 black crappie, which was highest during 1995. Thus, recruitment of black crappie was …
Drought-Induced Shift Of A Forest–Woodland Ecotone: Rapid Landscape Response To Climate Variation, Craig Allen, David D. Breshears
Drought-Induced Shift Of A Forest–Woodland Ecotone: Rapid Landscape Response To Climate Variation, Craig Allen, David D. Breshears
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
In coming decades, global climate changes are expected to produce large shifts in vegetation distributions at unprecedented rates. These shifts are expected to be most rapid and extreme at ecotones, the boundaries between ecosystems, particularly those in semiarid landscapes. However, current models do not adequately provide for such rapid effects—particularly those caused by mortality—largely because of the lack of data from field studies. Here we report the most rapid landscape-scale shift of a woody ecotone ever documented: in northern New Mexico in the 1950s, the ecotone between semiarid ponderosa pine forest and pinon– juniper woodland shifted extensively (2 km or …
Ecological Resilience, Biodiversity, And Scale, Garry D. Peterson, Craig R. Allen, C. S. Holling
Ecological Resilience, Biodiversity, And Scale, Garry D. Peterson, Craig R. Allen, C. S. Holling
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
We describe existing models of the relationship between species diversity and ecological function, and propose a conceptual model that relates species richness, ecological resilience, and scale.We suggest that species interact with scale-dependent sets of ecological structures and processes that determine functional opportunities. We propose that ecological resilience is generated by diverse, but overlapping, function within a scale and by apparently redundant species that operate at different scales, thereby reinforcing function across scales. The distribution of functional diversity within and across scales enables regeneration and renewal to occur following ecological disruption over a wide range of scales.
Idealwise Algebraic Independence For Elements Of The Completion Of A Local Domain, William Heinzer, Christel Rotthaus, Sylvia Wiegand
Idealwise Algebraic Independence For Elements Of The Completion Of A Local Domain, William Heinzer, Christel Rotthaus, Sylvia Wiegand
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Over the past forty years many examples in commutative algebra have been constructed using the following principle: Let k be a field, let S k[xl Xn]x,xn) be a localized polynomial ring over k, and let a be an ideal in the completion S of S such that the associated prims of a are in the generic formal fiber of S; that is, p N S (0) for each p Ass(S/a):. Then S embeds in S/a, the fraction field Q(S) of S embeds in the fraction ring of S/a, and for certain choices of a, the intersection D Q(S) f3 (S/a) …
Effects Of Red Imported Fire Ants On Recruitment Of White-Tailed Deer Fawns, Craig R. Allen, Stephen Demarais, R. Scott Lutz
Effects Of Red Imported Fire Ants On Recruitment Of White-Tailed Deer Fawns, Craig R. Allen, Stephen Demarais, R. Scott Lutz
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
We investigated the effect of red imported fire ants (RIFA; Solenopsis invicta) on an index of whitetailed deer (Odocoileus virginianus) fawn recruitment (doe:fawn ratio) on 10 200-ha plots in the Texas Coastal Prairie during 1991-93. Five of the plots received treatments of the fire ant bait AMDRO© (Am. Cyanamid Co., Wayne, N.].) during April and October 1991 and May 1992 to reduce RIFA populations. The remaining 5 plots served as untreated comparison areas. Populations of RIFA were reduced (P < 0.10) on treated study areas during deer fawning periods in 1991-92. Fawn recruitment was higher on treated areas during 1991 (P = 0.037) and 1992 (P = 0.069), with recruitment about twice as high on treated areas. In 1993, after 1 year of RIFA reinfestation, fawn recruitment did not differ between treated and untreated plots (P = 0.443). We conclude that high density RIFA infestations reduced white-tailed deer fawn recruitment.
Environmental Characteristics Of Black Crappie (Pomoxis Nigromaculatus) Nesting Sites In Two South Dakota Waters, K. L. Pope, D. W. Willis
Environmental Characteristics Of Black Crappie (Pomoxis Nigromaculatus) Nesting Sites In Two South Dakota Waters, K. L. Pope, D. W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
A biotelemetry study was undertaken during spring 1995 to identify black crappie (Pomoxis nigromaculatus) nesting sites in two South Dakota water bodies. Individually coded ultrasonic transmitters were implanted into the body cavity of 15 adult male black crappie in each water body prior to spawning. Available habitat characteristics were recorded at 75 randomly selected sites within each water body, and habitat characteristics at nesting sites were recorded for each male black crappie believed to be nesting. Of the habitat characteristics analyzed, only substrate firmness did not differ (P=0.79) between water bodies. In Richmond Lake, black crappie selected nesting …
Effect Of Red Imported Fire Ant Envenomization On Neonatal American Alligators, Craig R. Allen, Kenneth G. Rice, Daniel P. Wojcik, H. Franklin Percival
Effect Of Red Imported Fire Ant Envenomization On Neonatal American Alligators, Craig R. Allen, Kenneth G. Rice, Daniel P. Wojcik, H. Franklin Percival
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Alligator populations in the southeastern United States have substantially recovered since the late 1960s when they were placed on the federal Endangered Species List (Joanen and McNease, 1987). In Florida, both early age class and adult animals currently are harvested for commercial and recreational purposes (Hines and Abercrombie, 1987). In addition, the alligator is ecologically important as a keystone species and as an indicator of wetland health (Mazzotti and Brandt, 1994). Recently, the nonnative ant Solenopsis invicta (the red imported fire ant) has surfaced as a potential threat to alligator populations. Solenopsis invicta is a relatively new (approx. 65 yr) …
Oxytetracycline Marking Efficacy For Yellow Perch Fingerlings And Temporal Assays Of Tissue Residues, Eric G. Unkenholz, Michael L. Brown, Kevin L. Pope
Oxytetracycline Marking Efficacy For Yellow Perch Fingerlings And Temporal Assays Of Tissue Residues, Eric G. Unkenholz, Michael L. Brown, Kevin L. Pope
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Differentiating between hatchery and naturally reproduced fishes is difficult because of the lack of appropriate marking techniques. Chemical immersion techniques can be a practical method for mass marking juvenile fishes. The objectives of this study were to determine the concentration of oxytetracycline (OTC) hydrochloride needed to effectively mark age-0 yellow perch Perca flavescens to observe the retention lime of the mark, and to measure the persistence of OTC in body tissues. Fish were immersed in 309, 534, and 748 mg OTC/L for 12 h. Initial fish collections were made weekly, and monthly collections began 1 month postmarking for tissue and …
Back-Calculated Length-At-Age Estimates From Two Scale Radii, Keith L. Hurley, Kevin L. Pope, David W. Willis
Back-Calculated Length-At-Age Estimates From Two Scale Radii, Keith L. Hurley, Kevin L. Pope, David W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Variability in length-at-age estimates back-calculated from scales continues to be of concern to fishery scientists. Measurement transects used to back-calculate length at age have been recommended; however, specific scale and annuli radius measurements have not been evaluated for variability between different radii. Thus, the purpose of our study was to compare back-calculated length-at-age estimates determined from two different scale radii: one horizontally from the focus to the anterior-median edge and one diagonally from the focus to the anterior-lateral corner of the scale. No significant differences (P = 0.13 - 0.58 and P = 0.24 - 0.87) in backcalculated length-at-age estimates …
Egg Development In A High-Density Black Crappie (Pomoxis Nigromacuiatus) Population, Kevin L. Pope, Wade T. Geraets, David W. Willis
Egg Development In A High-Density Black Crappie (Pomoxis Nigromacuiatus) Population, Kevin L. Pope, Wade T. Geraets, David W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Female black crappie (Pomoxis nigromaculatus) were collected from Richmond Lake, South Dakota" and egg-diameter frequencies were examined to document spawning strategy during 1994. Two hundred and sixteen adult females [mean total length (TL) ±SE = 204 ± 1 mm] were collected and 85,572 egg diameters were measured. Female black crappie gonadosomatic-index (GSI) values exceeded 8% from 18 May to 22 June 1994, and the density of larval black crappie caught with an ichthyoplankton net peaked on 8 June 1994. The GSI values and larval catches indicated that the population, as a whole, had a single extended spawn from …
Effects Of Red Imported Fire Ants On Northern Bobwhite Chicks, William M. Giuliano, Craig R. Allen, R. Scott Lutz, Stephen Demarais
Effects Of Red Imported Fire Ants On Northern Bobwhite Chicks, William M. Giuliano, Craig R. Allen, R. Scott Lutz, Stephen Demarais
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Populations of red imported fire ants (RIFA; Solenopsis invtcta) have spread rapidly throughout the southeastern United States. RIFA, directly or indirectly, negatively affect many wildlife species, and northern bobwhite (Colinus virginianus) appear to be particularly susceptible. We examined the effect of exposure to different numbers of RIFA for 15 and 60 seconds on body mass and survival of captive northern bobwhite chicks. Compared to unexposed birds, survival of chicks was reduced with exposure to as few as 50 RIFA for 60 seconds, or 200 RIFA for 15 seconds, and body mass was lower in chicks exposed to …
Seasonal Influences On Freshwater Fisheries Sampling Data, Kevin L. Pope, David W. Willis
Seasonal Influences On Freshwater Fisheries Sampling Data, Kevin L. Pope, David W. Willis
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Fisheries managers often assess fish populations using catch per unit effort (CPUE), size and age structure, growth, and condition. For many freshwater fishes and common sampling gears, CPUE, size and age structure, and condition are highest in the spring and fall, while growth commonly is fastest during the summer growing season. However, there are exceptions to these general trends, especially in populations with erratic recruitment, growth, or mortality. At the least, CPUE, size and age structure, growth, and condition of fish should be expected to change with season, given the effects of variable recruitment, growth, and mortality. However, if recruitment, …
An Assessment Of Burbot (Lota Iota) Weight - Length Data From North American Populations, Shannon J. Fisher, David W. Willis, Kevin L. Pope
An Assessment Of Burbot (Lota Iota) Weight - Length Data From North American Populations, Shannon J. Fisher, David W. Willis, Kevin L. Pope
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Declining buroot (Lola lola) abundance across some portions of North America has prompted a search for additional evaluation tools, including a measure of condition. Weight - length data were compiled for 10293 burbot from 79 North American populations. These data were used to develop a 75th percentile standard weight (W,) equation using the regression-line-percentile technique. The proposed equation is log10 W3 = - 4.868 + 2.898 log10 TL, where Ws is the standard weight in grams, and TL is the maximum total length in millimetres. The equation is valid for burbot ≥20 cm and …
Red Imported Fire Ant Impact On Wildlife: An Overview, Craig R. Allen, Stephen Demarais, R. Scott Lutz
Red Imported Fire Ant Impact On Wildlife: An Overview, Craig R. Allen, Stephen Demarais, R. Scott Lutz
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
We reviewed the past 50 years of literature concerning red imported fire ant impacts on wildlife species. The red imported fire ant has had a negative impact on numerous species of wildlife. However, experimental evidence of population-level impacts is meager. We discuss potential fire ant perturbations and suggest research directions that may settle the long-standing controversy concerning the impact of imported fire ants on native vertebrates and the ecosystems they have invaded.
Interactions Between Larval White Crappie And Gizzard Shad: Quantifying Mechanisms In Small Ponds, Kevin L. Pope, Dennis R. Devries
Interactions Between Larval White Crappie And Gizzard Shad: Quantifying Mechanisms In Small Ponds, Kevin L. Pope, Dennis R. Devries
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
To test potential competitive interactions between larvae of white crappie Pomoxis annularis and of gizzard shad Dorosoma cepedianum. we added adult gizzard shad to eight of twelve 0.1-ha ponds that had been stocked with adult white crappies. Larval white crappies and larval gizzard shad appeared within 1 week of one another and larval white crappie density did not differ between treatments. Zooplankton density declined similarly between treatments, and zooplankton species composition and size did not differ. Although larval white crappie and larval gizzard shad had moderate diet overlap, prey selection by white crappie did not differ between treatments. During …
Finitely Generated Modules Over Bezout Ringsrwiegand@Unl.Edu, Roger Wiegand, Sylvia Wiegand
Finitely Generated Modules Over Bezout Ringsrwiegand@Unl.Edu, Roger Wiegand, Sylvia Wiegand
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
Let R be a Bezout ring (a commutative ring in which all finitely generated ideals are principal), and let M be a finitely generated R -module. We will study questions of the following sort: (A) If every localization of M can be generated by n elements, can M itself be generated by n elements? (B) If M 0 R m = Rn for some m, n, is Af necessarily free? (C) If every localization of M has an element with zero annihilator, does M itself have such an element? We will answer these and related questions for various familiar classes …