bluuebunny/crossref_metadata_2025 huggingface dataset:
Heritabilities of Lipids in Young European American and African American Twins
Authors: Iliadou Anastasia , Snieder Harold , Wang Xiaoling , Treiber Frank A. , Davis Catherine L.
Published: May 2007

Twin studies of lipids have almost exclusively involved Caucasians. People of African descent are known to show a healthier lipid profile, but relatively little is known about ethnic differences in genetic and environmental influences on lipids. One hundred and six African American (AA) and 106 European American (EA) twins (30 singletons and 91 complete pairs: 49 monozygotic, 21 dizygotic and 21 opposite-sex) from the south-eastern United States were studied (mean age 17.9 ± 3.2 years; 79% fasting). Lipids were assayed with the Cholestech LDX system. Analyses were adjusted for fasting status. Generalized estimating equations were used to test for the effects of sex and ethnicity on means, controlling for the dependence within twin pairs. Structural equation modeling was used to estimate genetic and environmental effects on each lipid variable. Females showed higher high-density lipoprotein (HDL) values than males (p< .001) and AAs showed higher HDL values than EAs (p< .001). EA males had higher triglyceride values than other groups (p= .02). All parameter estimates could be set equal across sex. Parameter estimates for total cholesterol, triglycerides and HDL could be set equal across ethnicity. The best fitting model for low- density lipoprotein (LDL) showed higher heritability in AAs (.92) than EAs (.69). Heritabilities ranged from 69% to 92%, with remaining variation explained by nonshared environmental effects. Adjustment for body mass index had virtually no effect on the heritability estimates. In this first twin study on lipids to include AAs, no ethnic differences in heritability were found except for LDL, where AAs exhibited higher estimates.
Heritability and Stability of Resting Blood Pressure
Authors: Hottenga Jouke-Jan , Boomsma Dorret I. , Kupper Nina , Posthuma Danielle , Snieder Harold , Willemsen Gonneke , de Geus Eco J. C.
Published: May 2007

We examined the contribution of genetic and environmental influences to variation in resting systolic (SBP) and diastolic (DBP) blood pressure in participants from 4 twin studies carried out between 1986 and 2003. A total of 1577 subjects (682 males, 895 females) participated. There were 580 monozygotic twins, 664 dizygotic twins and 333 of their siblings. The 4 studies sampled subjects in different age groups (average age 17, 32, 37, 44 years), allowing for comparison of the relative contribution of genetic and environmental factors across the first part of the life span. Blood pressure was assessed under laboratory conditions in 3 studies and by ambulatory monitoring in 1 study. Univariate analyses of SBP and DBP showed significant heritability of blood pressure in all studies (SBP h2 48% to 60%, DBP h2 34% to 67%). Overall, there was little evidence for sex differences in blood pressure heritability, and no evidence for differences in heritability due to measurement strategy (laboratory vs. ambulatory). For 431 subjects there were data from 2 or more occasions that allowed us to assess the tracking of blood pressure over time and to estimate the genetic and environmental contributions to blood pressure tracking. Correlations over time across an average period of 7.1 years (tracking) were between .41 and .70. Multivariate genetic analyses showed that blood pressure tracking was entirely explained by the same genetic factors being expressed across time. It was concluded that whole genome scans for resting blood pressure can safely pool data from males and females, laboratory and ambulatory recordings, and different age cohorts.
Are Twins at Risk of Cancer: Results From the Swedish Family-Cancer Database
Authors: Hemminki Kari , Chen Bowang
Published: May 2007

A few twin studies on cancer have addressed questions on the possible carcinogenic or protective effects of twining by comparing the occurrence of cancer in twins and singletons. The nationwide Swedish Family-Cancer Database of 10.2 million individuals and 69,654 0- to 70-year-old twin pairs were used to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for all main cancers compared to singletons. The overall risk of cancer in same- or different-sex twins was at the same level as the risk for singletons. Testicular cancer, particularly seminoma, was increased among same-sex twins (1.54) and all twins to an SIR of 1.38. Among other tumors, neurinomas and nonthyroid endocrine gland tumors were increased. Colorectal cancers and leukemia were decreased among all twins. Melanoma and squamous cell skin cancer were decreased in male same-sex twins. The data on this unselected population of twins suggest that twinning per se is not a risk factor of cancer. In utero hormonal exposures or postnatal growth stimulation may be related to the risk of testicular cancer and pituitary tumors. Protective effects against colorectal cancer may be related to a beneficial diet, and in melanoma and skin cancer, to socioeconomic factors. The study involved multiple comparisons, and internal consistency between the results was one of the main factors considered for their plausibility. The results should encourage others working on twin and singleton populations to examine the specific associations and emerging hypotheses.
Risk of Infant Mortality Among Twins in Relation to Placental Abruption: Contributions of Preterm Birth and Restricted Fetal Growth
Authors: Ananth Cande V. , Smulian John C. , Srinivas Neela , Getahun Darios , Salihu Hamisu M.
Published: May 2007

While preterm birth and restricted fetal growth are strongly associated with infant mortality, the extent to which these associations are modified by placental abruption remains unknown. A retrospective cohort study was carried out to examine the risk of infant mortality among twins in relation to abruption, and explore the independent contributions of preterm birth and restricted fetal growth to these associations. The study was restricted to women who had delivered twins at 22 weeks' gestation or more and fetuses weighing 500 grams or more in the United States (1989–2000). Risks of preterm birth (less than 37 weeks' gestation), fetal growth restriction and infant mortality, in relation to placental abruption, were evaluated. All analyses were adjusted for potential sociodemographic confounding factors. The association between restricted twin fetal growth and abruption was the strongest among the most severely growth-restricted babies (i.e., less than 1 centile), with the strength of association diminishing with increasing birthweight centiles. The risk of preterm birth among pregnancies with and without abruption were 80.1% and 51.9%, respectively (relative risk [RR] 1.5, 95% confidence interval [CI] 1.4–1.6). The risk of small-for-gestational-age (SGA; birthweight of less than the 10th centile for gestational age) among abruption and nonabruption births was 11.7% and 9.2%, respectively (RR 1.3, 95% CI 1.2–1.4). Compared with twins of the appropriate growth delivered at term, the relative risks for infant mortality in the presence of abruption were 9.9 (95% CI 5.4–18.2) for term-SGA, 25.0 (95% CI 22.3–28.1) for preterm-non-SGA, and 36.2 (95% CI 28.4–46.1) for preterm-SGA births. The association between infant mortality and abruption among twins appears largely mediated through preterm birth, and to a lesser extent, through SGA. The association between fetal growth and abruption is strongest among the severely growth-restricted babies, suggesting that the origins of placental abruption may develop in early pregnancy.
Causal Hypothesis for Some Congenital Anomalies
Authors: Pharoah Peter O. D.
Published: May 2007

Congenital anomalies are a major cause of fetal and neonatal death and of childhood morbidity. Chromosomal and other genetic abnormalities, environmental teratogens and some nutritional deficiencies account for some congenital anomalies but the majority are of unknown etiology. The hypothesis is here proposed that a significant proportion of congenital anomalies and cerebral palsy of unknown etiology are attributable to a monozygotic multiple conception with monochorionic placentation and that these anomalies, even in singletons, may be explained by early, unrecognized or unrecorded loss of one conceptus in a monochorionic monozygotic conception. The pathological mechanism is hemodynamic instability with episodes of acute feto–fetal transfusion that produce ischemic organ impairment in either or both twins. The resultant clinical abnormality will depend on range of severity (fetal death, infant death, congenital anomaly, normal infant), site or combination of sites (which organ[s] present[s] with the congenital anomaly) and timing (early, middle or late in gestation as shown by variation in brain pathology that is observed).
Problems With Using Sum Scores for Estimating Variance Components: Contamination and Measurement Noninvariance
Authors: Neale Michael C. , Lubke Gitta , Aggen Steven H. , Dolan Conor V.
Published: May 2007

Twin studies of complex traits, such as behavior or psychiatric diagnoses, frequently involve univariate analysis of a sum score derived from multiple items. In this article, we show that absence of measurement invariance across zygosity can bias estimates of genetic and environmental components of variance. Specifically, if the item responses are considered as multiple indicators of a latent factor, and the aim is to partition the variance in the latent factor, then the factor loadings relating the items to the factor should be equal for monozygotic (MZ) and dizygotic (DZ) twins. While it seems unlikely, a priori, that these loadings should differ as a function of zygosity, certain special measurement situations are cause for concern. Ratings by parents, or self-ratings of pheno- types which are more easily observed in others than via introspection, may be tainted by the co-twin's phenotype to a greater extent in MZ than DZ pairs. We also show that the analysis of sum scores typically biases both MZ and DZ correlations compared to the true latent trait correlation. These two sources of bias are quantified for a range of values and are shown to be especially acute for sum scores based on binary items. Solutions to these problems include formal tests for measurement invariance across zygosity prior to analysis of the sum or scale scores, and multivariate genetic analysis at the individual item or symptom level.
Parameterization of Sex-Limited Autosomal Linkage Analysis for Mx
Authors: Medland Sarah E.
Published: May 2007

Incorporation of sex-limitation (genotype-sex interaction) effects into a model of quantitative trait loci (QTL) analysis has been shown to increase the power to detect linkage when analyzing traits in which sex limitation is present (Towne et al., 1997). The present note provides a parameterization of the nonscalar sex-limitation ACE model incorporating autosomal sex-limited QTL effects for use with the Mx matrix algebra program (Neale et al., 2002). An example script designed for use with extended sib- ships that takes advantage of the versatile treatment of covariates within Mx is included.
The Etiology of Mathematical and Reading (Dis)ability Covariation in a Sample of Dutch Twins
Authors: Markowitz Ezra M. , Willemsen Gonneke , Trumbetta Susan L. , van Beijsterveldt Toos C. E. M. , Boomsma Dorret I.
Published: May 2007

The genetic etiology of mathematical and reading (dis)ability has been studied in a number of distinct samples, but the true nature of the relationship between the two remains unclear. Data from the Netherlands Twin Register was used to determine the etiology of the relationship between mathematical and reading (dis)ability in adolescent twins. Ratings of mathematical and reading problems were obtained from parents of over 1500 twin pairs. Results of bivariate structural equation modeling showed a genetic correlation around .60, which explained over 90% of the phenotypic correlation between mathematical and reading ability. The genetic model was the same for males and females.
Sex-Limited Genome-Wide Linkage Scan for Body Mass Index in an Unselected Sample of 933 Australian Twin Families
Authors: Cornes Belinda K. , Medland Sarah E. , Ferreira Manuel A. R. , Morley Katherine I. , Duffy David L. , Heijmans Bastiaan T. , Montgomery Grant W. , Martin Nicholas G.
Published: May 2007

Genes involved in pathways regulating body weight may operate differently in men and women. To determine whether sex-limited genes influence the obesity-related phenotype body mass index (BMI), we have conducted a general non- scalar sex-limited genome-wide linkage scan using variance components analysis in Mx (Neale, 2002). BMI measurements and genotypic data were available for 2053 Australian female and male adult twins and their siblings from 933 families. Clinical measures of BMI were available for 64.4% of these individuals, while only self-reported measures were available for the remaining participants. The mean age of participants was 39.0 years of age (SD 12.1 years). The use of a sex-limited linkage model identified areas on the genome where quantitative trait loci (QTL) effects differ between the sexes, particularly on chromosome 8 and 20, providing us with evidence that some of the genes responsible for BMI may have different effects in men and women. Our highest linkage peak was observed at 12q24 (–log10p = 3.02), which was near the recommended threshold for suggestive linkage (–log10p = 3.13). Previous studies have found evidence for a quantitative trait locus on 12q24 affecting BMI in a wide range of populations, and candidate genes for non- insulin-dependent diabetes mellitus, a consequence of obesity, have also been mapped to this region. We also identified many peaks near a –log10p of 2 (threshold for replicating an existing finding) in many areas across the genome that are within regions previously identified by other studies, as well as in locations that harbor genes known to influence weight regulation.
Association Between Dopamine D4 Receptor Exon III Polymorphism and Emotional Reactivity as a Temperamental Trait
Authors: Oniszczenko Wlodzimierz , Dragan Wojciech L.
Published: May 2007

The association between high and low levels of emotional reactivity (ER) as a temperamental trait and the dopamine D4 receptor (DRD4) exon III polymorphism in healthy men aged 18 to 27 (M= 21.03,SD= 2.23) was examined. ER, measured by the Formal Characteristics of Behavior–Temperament Inventory (FCB-TI), is defined as a tendency to react intensively to emotion-generating stimuli and is expressed in high emotional sensitivity and in low emotional endurance. Data analysis demonstrated a statistically significant difference in the distribution of genotypic frequencies between the low and high ER groups:χ2= 4.88;df= 1;p= .027, odds ratio (OR) =2.85, 95% confidence interval (CI) = 1.11–7.32. An insignificant difference in allele frequencies between the two groups was noted:χ2= 7.47;df= 3;p= .058; OR = 2.9, 95% CI = 1.29–6.53. These findings suggest a role of the DRD4 exon III polymorphism in the modulation of ER as a temperamental trait. Due to the preliminary nature of our findings, replication is necessary.
Temperature-Mediated Differences in Bacterial Kidney Disease Expression and Survival in Renibacterium salmoninarum-challenged Bull Trout and Other Salmonids
Authors: Jones Darin T. , Moffitt Christine M. , Peters K. Kenneth
Published: May 2007

Resource managers considering restoration and reconnection of watersheds to protect and enhance threatened populations of bull trout Salvelinus confluentus have little information about the consequences of bacterial kidney disease (BKD) caused by Renibacterium salmoninarum. To better understand the response of bull trout to R. salmoninarum challenge, we conducted several laboratory experiments at two water temperatures. The extent, severity, and lethality of BKD in bull trout were compared with those of similarly challenged lake trout S. namaycush, Arctic char S. alpinus, Chinook salmon Oncorhynchus tshawytscha, and rainbow trout O. mykiss. The lethal dose of bacterial cells necessary to induce 50% mortality (LD50) was 10-fold lower at the 15°C challenge than at the 9°C challenge. Of the species tested, bull trout were relatively resistant to BKD, Arctic char were the most susceptible among Salvelinus species, and Chinook salmon were the most susceptible among Oncorhynchus species tested. Mean time to death was more rapid for all fish tested at 15°C than for fish challenged at 9°C. These results suggest that infection of bull trout with BKD likely poses a low risk to successful restoration of threatened populations.
Seasonal Natural and Fishing Mortality of Striped Bass in a Southeastern Reservoir
Authors: Thompson Jessica S. , Waters D. Scott , Rice James A. , Hightower Joseph E.
Published: May 2007

Reliable estimates of natural and fishing mortality are important for management of exploited fish populations, but these components of the total mortality rate can be difficult to determine by traditional fisheries methods. We used telemetry data to determine seasonal instantaneous fishing (F) and natural mortality (M) rates of subadult and adult striped bass Morone saxatilis in Badin Lake, North Carolina. Our analyses were based on the fates of 64 fish implanted with sonic transmitters and released and tracked for 2 years. Natural mortality was low and constant during the course of the study (M ± SE = 0.10 ± 0.01) and was similar to estimates for other reservoir populations of striped bass. A natural mortality rate of 0.09–0.16 may be a reasonable approximation for populations across the southeastern United States. Fishing mortality varied seasonally and was highest in the spring and summer of 2002 and the summer and fall of 2003; annual fishing mortality (F ± SE) was 0.65 ± 0.08 in 2002 and 0.77 ± 0.08 in 2003. Due to these high harvest rates, estimated annual survival rates were low for the Badin Lake population (47% in 2002; 42% in 2003). Results of a yield-per-recruit model suggest that harvest of older, larger individuals can be increased in Badin Lake with a decrease in fishing mortality or a moderate increase in the minimum size limit, even when the effect of catch-and-release mortality of fish below the size limit is considered. Our results also indicate important considerations for researchers using this method in the future, including the need to estimate downstream emigration and delay the inclusion of newly tagged fish in analysis to avoid biasing estimates of fishing mortality.
Evaluating Creel Survey Efficiency for Estimating Walleye Fishery Metrics in Northern Wisconsin Lakes
Authors: Deroba Jonathan J. , Hansen Michael J. , Nate Nancy A. , Hennessy Joseph M.
Published: May 2007

To determine whether creel survey efficiency can be improved in northern Wisconsin lakes, we compared estimates of effort, harvest rate, harvest, recapture rate for previously marked fish (R/C ratio), and recaptures of walleyes Sander vitreus from four reduced-sampling-effort schemes (eliminating 1 week per month, 2 weeks per month, odd-numbered weeks, and even-numbered weeks) in each month of the angling season with estimates from creel surveys during 1991–2002. Estimates of angler-hours from each reduced-sampling-effort scheme differed significantly from those from the full sampling effort in several months, and variances differed significantly in nearly all months. Estimates of walleyes harvested per hour from each reduced-sampling-effort scheme differed significantly from those from the full sampling effort only in May or June, and variances differed significantly in several months for all sampling effort schemes except that of 1 week per month. Estimates of walleye harvest from all reduced-sampling-effort schemes differed significantly from those from the full sampling effort for at most 2 months, but variances did not differ significantly in several months. Estimates of the R/C ratio from all reduced-sampling-effort schemes differed significantly from those from the full sampling effort for at most 2 months, but variances differed significantly in several months. Estimates of the number of recaptures differed significantly from those from the full sampling effort for several months with the elimination of 1 week per month and 2 weeks per month but did not differ significantly with the elimination of odd- or even-numbered weeks, and variances differed significantly in several months for all reduced-sampling-effort schemes. Creel survey efficiency cannot be improved using these sampling effort reductions without causing significant losses in accuracy and precision.
Problem Solving Variations in an Online Programming Course
Authors: Ebrahimi Alireza
Published: May 2007

An observation on teaching introductory programming courses on SLN for a period of two terms led me to believe that online students try various ways to solve a problem. In the beginning, I got the impression that some of their approaches for a solution were wrong; but after a little investigation, I found that some of the problem-solving approaches were correct but difficult to understand and not straightforward. However, some of the solutions were interesting, challenging, and unique. Three problem sets will be discussed which were given from the textbook in modules 2 and 3 of the term. The problems were to compute salary with overtime, compute total average mileage per gallon, and parking charge fee. As an instructor who has taught introductory programming for more than two decades, I found several variations in solving a problem, even in a small simple program like a compute salary program. One speculation would be that students use trial and error and use their own logic to get the correct output, despite not using a common approach. It seems that students in face-to-face classes focus on the information from the instructor and disseminate ideas among each other.
Strategic Self Development for Successful Aging at Work
Authors: Robson Sean M. , Hansson Robert O.
Published: May 2007

Two studies involving 265 participants were conducted to assess the content and range of strategies used by employees to age successfully in the workplace. Study 1 included 64 individuals ranging in age from 23 to 61. These individuals were asked to list up to five activities they have pursued in five potentially important areas of development. Content analyses on these activities were then conducted for purposes of item development. In the second study, the sample was limited to 201 older workers, defined as employees age 40 and older. Participants completed several scales examining the frequency with which they engaged in activities related to successful aging at work. Factor analyses indicated seven major types of strategies: 1) Relationship Development, 2) Security, 3) Continuous Learning, 4) Stress-Relief, 5) Skill Extension, 6) Career Management, and 7) Conscientiousness. Analyses indicated that each strategy domain was positively related to perceived success. Furthermore, hierarchical regression analyses indicated that Security, Relationship Development, Continuous Learning, and Career Management strategies were predictive of success above and beyond important characteristics of the individual or employing organization. The results also indicated that age moderated the relationship between strategy use and perceived success for two strategy domains. Relationship Development and Skill Extension strategies were less strongly related to perceived success as employees aged. Implications of these findings are discussed in relation to theory development, application, and future research.
The Blackboard Learning System: The Be All and End All in Educational Instruction?
Authors: Bradford Peter , Porciello Margaret , Balkon Nancy , Backus Debra
Published: May 2007

Blackboard Inc. provides powerful and easy-to-use systems for educational instruction, communication, and assessment. In the last three years, Blackboard Inc. has marketed two major product lines: the Blackboard Commerce Suite and the Blackboard Academic Suite. The core of the Academic suite is the Blackboard Learning System, the course management system for classroom and online educational assistance. Other course management systems and learning management systems exist, including Angel/LMS, eCollege, GNU General Public License/Linux, and LearningSpace, as well as open-source learning systems such as The Sakai Project, Open SourcePortfolio Initiative, Moodle, and uPortal. Despite the drive toward new portal commodities, the Blackboard Learning System has become the dominant e-learning software company. Is this necessarily good for higher educational learning? Members of the United University Professions Technology Issues Committee debate the issue as well as present specific applications of the Blackboard Learning System in distance learning, hybrid courses, and as didactic supplements to other electronic environment enhancement systems.
A Review of Cheating in Fully Asynchronous Online Courses: A Math or Fact-Based Course Perspective
Authors: Trenholm Sven
Published: May 2007

Un-proctored fully asynchronous1 online courses now appear to be a reality in all discipline areas. With full degree programs being offered online, it has become a badge of honor, to some colleges, to graduate students that have never stepped foot on the physical college campus nor have never before met any college representative, faculty, or staff. To many involved in managing, teaching, and implementing these online courses, the idea of academic integrity related to courses taught in a fully online un-proctored modality is therefore of great interest and concern. This review represents a deliberate effort to distinguish the issue of academic integrity in fully asynchronous online courses into two categories: “Writing-Based” (WB) vs. “Math or Fact-Based” (MFB) courses. WB courses, which tend to be subjective in nature, include discipline areas such as English, history, psychology… . MFB courses, which emphasize calculation and/or factual recall, have a tendency to be highly objective in nature, and include discipline areas such as math, science, business, computers, medical technology… . While there are certainly significant areas of overlap in how different assessment instruments are administered in these two categories, most math and many science courses, for instance, tend to focus on calculation and fact-based assessment instruments (such as mid-term and final exams) and most English and history courses, for example, tend to focus on writing-based assessment instruments (such as written assignments and term papers). Based on this distinction, the notion that pedagogical mechanisms (apart from proctored assessments) are sufficient to ensure academic integrity in online MFB courses is questioned and challenged. Recommendations are given to advance the use of proctored assessments in online MFB courses through the creation of universal proctoring standards and the expansion of current and new testing center networks.
Quantifying the Origin of Woodcock Wintering in France
Authors: BAUTHIAN ISABELLE , GOSSMANN FRANÇOIS , FERRAND YVES , JULLIARD ROMAIN
Published: May 2007

Abstract: Migratory birds wintering at the same location are usually coming from populations of different origins, in variable proportions. Using data from individuals banded on their wintering grounds and recovered on their breeding areas, we show that such proportions are estimable given that 1) all breeding populations are identified, and 2) the wintering population can be stratified into ≥1 more site than the number of breeding populations. We applied this technique to woodcock (Scolopax rusticola) banded while wintering in France (N = 35,000) and recovered in other European countries (N = 520). We estimated that the proportion of eastern woodcock among those wintering in France varied spatially, ranging from 70% in northwest France to nearly 100% in southeast France, and increased substantially over the last 15 years. Overall, the method appears powerful to quantify spatial variation of the composition of a population receiving individuals from various origins.
Long‐Term Retention of a Relocated Population of Gopher Tortoises
Authors: ASHTON KYLE G. , BURKE RUSSELL L.
Published: May 2007

Abstract: Relocations of gopher tortoises (Gopherus polyphemus) in Florida, USA, are frequently employed as mitigation tools when tortoises occupy land desired for development. Here we present information about retention and health of a relocated population of gopher tortoises 17 years after relocation. We combine our 17‐year postrelocation data with earlier surveys 1 year and 2 years postrelocation to examine whether retention rates change over time. We also evaluate whether retention rates vary by age and gender. Of 74 gopher tortoises relocated in 1985, 31 were present in 2002. We found a 1‐year retention rate of 42%, with retention rates of 100% each year thereafter, when we used the percentage of relocated individuals captured at each survey. We found a 1‐year retention rate of 73%, a retention rate of 92% from year 1 to year 2, and an overall retention rate of 98.5% from year 2 through year 17, based on the assumption that all individuals present in later surveys were present in earlier surveys. We found no significant difference in retention rate over the 17‐year period for adults and juveniles and for adult males and females. Relocated gopher tortoises showed natural growth patterns, indicating good health, but 35% of these gopher tortoises had ≥1 symptom of upper respiratory tract disease, a disease associated elsewhere with population declines of tortoises. Thus, retention rates of relocated gopher tortoises change over time, with relatively low retention during the first year postrelocation but nearly 100% retention in subsequent years. In general, our study shows that relocations can successfully lead to long‐term retention of gopher tortoises, but we predict that without management (e.g., fire management and predator control) this relocated population is not viable.
Biases in Trapping Larval Amphibians in Playa Wetlands
Authors: GHIOCA DANA M. , SMITH LOREN M.
Published: May 2007

Abstract:Standardized, effective sampling methods are required to monitor amphibian population trends and community composition. Funnel traps have been used to ostensibly estimate species richness and relative abundance of larval amphibians. We tested whether funnel traps can be used to provide unbiased estimates of amphibian community composition in playa wetlands by comparing seining—dip netting and passive funnel‐trapping results. Plains spadefoots (Spea bombifrons) were more prone to be captured in funnel traps whereas New Mexico spadefoots (S. multiplicata) were less likely captured by funnel traps than by seines and dip nets. In playas funnel traps should be used only for collecting specimens and not for estimating amphibian community composition.
Survival of Pronghorns in Western South Dakota
Authors: JACQUES CHRISTOPHER N. , JENKS JONATHAN A. , SIEVERS JARET D. , RODDY DANIEL E. , LINDZEY FREDERICK G.
Published: May 2007

Abstract: Survival and cause‐specific mortality of pronghorns (Antilocapra americana) have been well‐documented in several western states and Canadian provinces. However, no information has been collected in western South Dakota, USA, where mixed‐grass prairie habitats characterize rangelands. The objectives of our study were to determine survival and cause‐specific mortality of adult (>18 months) and yearling (6‐18 months) pronghorns and to determine monthly and summer (Jun‐Aug) survival for neonatal (<1 month of age) pronghorns in South Dakota. We radiocollared 93 adult female and 142 neonatal pronghorns on 3 areas in western South Dakota. We used bed sites from initial neonate captures to collect microhabitat information throughout Harding and Fall River counties. We measured vegetation understory and overstory height, shrub canopy, and distance to nearest concealment cover to the nearest centimeter inside 1‐m2 quadrats by collecting measurements at 15 random points within a 30‐m radius of the bed site. We documented that coyote (Canis latrans) predation was the primary cause of mortality for neonates in western South Dakota and that microhabitat characteristics at neonate bed sites differed between northwestern and southwestern South Dakota. More intensive aerial predator control may increase neonate survival in Fall River County. Management of rangelands by state and federal employees throughout western South Dakota and Wind Cave National Park that maximizes height of overstory and understory vegetation would provide neonates with adequate concealment cover for protection from predators, thereby increasing 4‐week and 12‐week postcapture survival. Our study provides South Dakota game managers with region‐specific, annual and seasonal survival rates that were previously only estimated, thus improving the accuracy of simulated pronghorn population model output. Hunting was the primary cause of mortality (26%) for adult females in Harding and Fall River counties, thereby confirming the continued use of annual harvest by South Dakota game managers as the primary management tool for maintaining pronghorn populations within statewide population management goals.
Predictive Occurrence Models for Bat Species in California
Authors: DUFF ANDREW A. , MORRELL THOMAS E.
Published: May 2007

Abstract:The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, andLasiurus cinereus) in Whiskeytown National Recreation Area in north‐central California, USA. We used landscape‐scale variables, logistic regression, and Akaike's Information Criterion (AICc) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape‐scale variables best discriminated between capture sites and non‐capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver‐haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver‐haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver‐haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.
Evidence for Regionally Synchronized Cycles in Texas Quail Population Dynamics
Authors: LUSK JEFFREY J. , GUTHERY FRED S. , PETERSON MARKUS J. , DEMASO STEPHEN J.
Published: May 2007

Abstract:Knowledge of the possible role of cyclic behavior in wildlife dynamics assists in understanding and managing populations. Using spectrum, we analyzed time series (1978‐2002) on the abundance of northern bobwhites (Colinus virginianus) and scaled quail (Callipepla squamata) in several ecological regions in Texas, USA, to test for the presence of cycles; we also tested whether drought severity (Modified Palmer Drought Severity Index) exhibited cyclic dynamics and whether quail and drought cycles were synchronized among regions. We found evidence of population cyclicity in all ecoregions we tested (5 for bobwhites, 4 for scaled quail) based on both Texas Parks and Wildlife and North American Breeding Bird Survey count data. Periods of the observed cycles generally were 5‐6 years (bobwhites) or 2‐3 years (scaled quail), depending on ecoregion and data source. Cyclicity was most pronounced for bobwhites in the Rolling Plains (north TX) and the South Texas Plains. The Palmer Index exhibited a roughly 5‐year cycle in 5 of 6 regions we tested. A 5‐year bobwhite and Palmer Index cycle were synchronous in 3 contiguous ecoregions totaling 27,200,000 ha. Wet‐dry cycles seemed to synchronize bobwhite cycles in Texas. Our results suggest that habitat manipulations aimed at improving habitat conditions during dry periods, such as reducing livestock stocking rates, could provide ground cover similar to that available in wet periods.
Habitat Selection of Female Turkeys in a Managed Pine Landscape in Mississippi
Authors: MILLER DARREN A. , CONNER L. MICHAEL
Published: May 2007

Abstract: Intensive pine (Pinus spp.) management is a dominant form of forest management in the southeastern United States. Previous research has shown that managed pine forests provide suitable habitat for eastern wild turkeys (Meleagris gallopavo silvestris), but little research has examined seasonal habitat selection for female wild turkeys from a landscape perspective, particularly within managed pine landscapes. Therefore, we used a long‐term (1986‐1993) data set to describe seasonal habitat selection by female wild turkeys, using an information‐theoretic approach from a landscape perspective, on an intensively managed pine landscape. Habitat use patterns during preincubation and autumn‐winter were indicative of female wild turkeys moving between a bottomland hardwood‐agricultural field complex during autumn‐winter and upland managed pine stands during the remainder of the year. During spring and summer, female wild turkeys used landscapes primarily composed of intensively managed pine, including thinned and burned stands and roadsides. Our results confirm results of short‐term, stand‐based habitat analyses on our study area. We recommend variable fire return intervals of 3 to 7 years to improve habitat conditions for wild turkeys within intensively managed pine forests. Further research is needed to examine management actions, such as thinning, prescribed fire, and herbicide use, within the context of wild turkey use of intensively managed pine landscapes.
Influence of Precipitation on Pronghorn Demography in Texas
Authors: SIMPSON DAVID C. , HARVESON LOUIS A. , BREWER CLAY E. , WALSER RYAN E. , SIDES AARON R.
Published: May 2007

Abstract: Ungulate populations in desert environments are thought to be regulated by precipitation. Pronghorn (Antilocapra americana) populations in Trans‐Pecos, Texas, USA, experienced a 70% decline between 1977 and 2001. The causative factors associated with the decline are unknown but appear to be related to drought. We evaluated the relationships between pronghorn abundance and productivity and precipitation (i.e., raw precipitation, Palmer Drought indices) for the Trans‐Pecos district of Texas from 1977 to 2004. Pronghorn productivity (range = 305‐4,407) and abundance (range = 5,061‐17,266) showed high variability. Precipitation was also highly variable, ranging from 18 cm to 57 cm. Pronghorn abundance was positively influenced by precipitation indices (R = 0.790, P < 0.001). The relationship between fawn production and raw precipitation (R = 0.869, P < 0.001) suggested that fawn production may be more closely related to immediate moisture conditions, whereas pronghorn abundance was more influenced by long‐term population trends. Management plans for pronghorn populations in more arid regions should include drought contingencies including reduced stocking rates and harvest quotas.
Habitat Use of Sympatric Rattlesnake Species Within the Gulf Coastal Plain
Authors: STEEN DAVID A. , SMITH LORA L. , CONNER L. MIKE , BROCK JEAN C. , HOSS SHANNON K.
Published: May 2007

Abstract:The eastern diamondback rattlesnake (Crotalus adamanteus) and timber rattlesnake (Crotalus horridus) are sympatric throughout most of southern Georgia, USA. We used rattlesnake sightings to quantify and compare habitat use by these 2 species in the Gulf Coastal Plain. At the largest scale examined, univariate statistics and logistic regression models indicated that eastern diamondback rattlesnakes were associated with roads but not with any of the specific habitat types we examined. In contrast, timber rattlesnakes were closely associated with hardwood habitat and riverine systems but not with roads and edges. To effectively conserve and manage both species in the Southeast, a habitat matrix of large intact patches of both hardwood and pine (Pinusspp.) forest may be necessary.
Optimizing Radio Retention and Minimizing Radio Impacts in a Field Study of Upland Sandpipers
Authors: MONG TONY W. , SANDERCOCK BRETT K.
Published: May 2007

Abstract:Two challenges in wildlife telemetry are optimizing the duration of transmitter attachment and minimizing the impacts of radios on the behavior and demography of the study animal. We tested 4 methods of radio attachment for a breeding population of upland sandpipers (Bartramia longicauda) under natural conditions at a tallgrass prairie site in Kansas, USA. To estimate radio retention and weekly survival rates, we used the nest survival model of Program MARK. Radio retention was lowest at the start and the end of the breeding period. The expected duration of radio retention was 1.8 years for a leg‐loop harness, 40 days for radios glued to clipped feathers, 26 days for radios glued directly to feathers, and 7 days for radios glued to bare skin. Few radiomarked birds died during our study, but 4 of 8 mortality events were discovered within one week of radiomarking. Both glue and harnesses increased predation risk immediately after radio attachment. The weekly probability of survival was high after a 1‐week acclimation period, and the expected survival for a 10‐week breeding period was similar in males and females. Attachment of radios with glue had no effect on annual return rates. However, attachment of radios with leg harnesses resulted in lower return rates among radiomarked birds than birds without radios. Radios attached with glue were shed in <1 year but radios attached with harnesses were retained for up to 1‐2 years. Our results indicate a tradeoff between optimizing radio retention and minimizing impacts on demography. Glue techniques had retention rates that were suitable for only short‐term studies, but attachment with glue had no long‐term effect on annual return rates. Leg harnesses provided effective radio retention that had little effect on survival rates during the stationary breeding period, but resulted in lower annual return rates. Robust estimates of radio retention and survival will assist researchers in selecting attachment techniques that best meet the study goals of future telemetry projects.
Testing a Mahalanobis Distance Model of Black Bear Habitat Use in the Ouachita Mountains of Oklahoma
Authors: HELLGREN ERIC C. , BALES SARA L. , GREGORY MARK S. , LESLIE DAVID M. , CLARK JOSEPH D.
Published: May 2007

Abstract:Regional wildlife‐habitat models are commonly developed but rarely tested with truly independent data. We tested a published habitat model for black bears(Ursus americanus)with new data collected in a different site in the same ecological region (i.e., Ouachita Mountains of Arkansas and Oklahoma, USA). We used a Mahalanobis distance model developed from relocations of black bears in Arkansas to produce a map layer of Mahalanobis distances on a study area in neighboring Oklahoma. We tested this modeled map layer with relocations of black bears on the Oklahoma area. The distributions of relocations of female black bears were consistent with model predictions. We conclude that this modeling approach can be used to predict regional suitability for a species of interest.
Accuracy of Lightweight Satellite Telemetry: A Case Study in the Iberian Peninsula
Authors: SOUTULLO ALVARO , CADAHIA LUIS , URIOS VICENTE , FERRER MIGUEL , NEGRO JUAN JOSÉ
Published: May 2007

Abstract: Here we provide the first assessment of the accuracy of lightweight satellite transmitters (<80 g) under actual operating conditions and the performance of the Argos system in southern Europe. To estimate transmitter accuracy we used transmitters equipped with a Global Positioning System (GPS) and compared the location estimates provided by Argos with the estimates provided by the GPS. Using the 68th percentile to define the accuracy of locations estimates, observed accuracy was 4 km for Location Class (LC) 1, 15 km for LC 0, 20 km for LC A, and 59 km for LC B, which is in line with estimates reported by other authors. Yet, the error of the remaining 32% of the data ranged between 4 km and 11 km, 15 km and 217 km, 20 km and 145 km, and 59 km and 493 km, respectively, suggesting that using the 68th percentile to estimate accuracies might give misleading confidence on the accuracy of location estimates. Using the 90th percentile is probably more appropriate. Less than 10% of the locations we obtained corresponded to the more accurate LCs (3, 2, and 1), with Argos failing to provide a position estimate in 45% of the attempts. The low number of high‐quality location estimates is likely a consequence of the electromagnetic interference reported for our study area, rather than a defect of the Platform Transmitter Terminals (PTTs), which under good conditions of signal reception seem to be as reliable as heavier ones. The recent advent of lightweight GPS transmitters overrides most of these problems. Yet, whereas the smallest Argos‐GPS PTTs weigh 30 g, which restricts their use to animals weighting > 1,000 g, conventional PTTs can be as small as 9.5 g, allowing their use with animals weighting 250‐300 g.
Survival, Fecundity, and Movements of Free‐Roaming Cats
Authors: SCHMIDT PAIGE M. , LOPEZ ROEL R. , COLLIER BRET A.
Published: May 2007

Abstract:Free ‐roaming cats (e.g., owned, semi‐feral, and feral) impact wildlife worldwide through predation, competition, and disease transmission. Baseline ecological information necessary for population management is lacking. We radiocollared free‐roaming cats (feral,n =30; semi‐feral,n =14; owned,n =10) in Caldwell, Texas, USA between October 2004 and November 2005 and compared population demographics among sex and ownership classification. We found ranges and movements declined across ownership classes whereas survival and fecundity increased. Our findings suggest that human interactions (e.g., feeding) may result in high, localized free‐roaming cat densities, which may concentrate feral cat impacts and should be considered when evaluating population control strategies.