bluuebunny/crossref_metadata_2025 huggingface dataset:
Instant centre frequency at anaesthetic induction – a new way to analyse sympathovagal balance†
Authors: De Souza Neto Edmundo Pereira , Cerutti Catherine , Loufoua Joseph , Saroul Christine , Chiari Pascal , Custaud Marc‐Antoine , Lehot Jean‐Jacques
Published: March 2003

The instant centre frequency (ICF) of RR interval has been proposed as a global index to analyse the sympathovagal interaction in the heart. The aim of this study was to assess the ICF during anaesthesia to test if it can reliably capture the neural control of the cardiovascular system. Twenty‐four ASA II or III patients scheduled for cardiac surgery were included in the study. They were allocated in two groups: control, no treatment (group 1, n = 12), and beta‐adrenergic blockade by atenolol (group 2, n = 12). Spectra of pulse interval series were computed with a time–frequency method and they were divided into: very low frequency (VLF, 0.000–0.040 Hz), low frequency (LF, 0.050–0.150 Hz) and high frequency (HF, 0.160–0.500 Hz). Normalized power was obtained by dividing the cumulative power within each frequency band (LF or HF) by the sum of LF and HF; the ratio of LF/HF was also calculated.

Instant centre frequency is a time‐varying parameter that the evolution along time of the gravity centrum of a local spectrum. All spectral indexes were recorded at the following time points: before induction, after induction and before intubation, during intubation, and after intubation. The atenolol group had lower normalized LF and the LF/HF ratio (P < 0.05) higher HF before induction; and lower LF/HF ratio after induction and before intubation (P < 0.05). The ICF was higher in atenolol group at all times. The ICF shifted towards HF frequency after induction and before intubation and shifted towards LF during intubation in both groups. The autonomic nervous system control on the heart through the interaction of sympathetic and parasympathetic reflex mechanisms could be studied by the ICF. The ICF may assess the autonomic cardiac modulation and may provide useful information for anaesthetic management.
ORIGINAL ARTICLE. Differential effects of sulphonylureas on the vasodilatory response evoked by KATP channel openers
Authors: Ravel Denis , Levens Nigel , Félétou Michel , Néliat Gervais , Auclair Jean , Bouskela Eliete
Published: March 2003

The potency of three sulphonylureas, glibenclamide, glimepiride and gliclazide in antagonizing the vasorelaxant action of openers of adenosine triphosphate (ATP)‐regulated K+ channel (KATP) was studied in vivo and in vitro in micro‐ and macrovessels, respectively. In the hamster cheek pouch, the vasodilatation and the increase in vascular diameter and blood flow induced by diazoxide were markedly reduced by the addition of either glibenclamide or glimepiride (0.8 μm) while they were not affected by gliclazide up to 12 μm. Similarly, in rat and guinea‐pig isolated aortic rings, glibenclamide, glimepiride and gliclazide reduced the vasodilator activity of cromakalim. However, the inhibitory effect of gliclazide was considerably less when compared with either glimepiride or glibenclamide. These results suggest that, in contrast to glibenclamide and glimepiride, therapeutically relevant concentrations of gliclazide do not block the vascular effects produced by KATP channel openers in various in vitro and in vivo animal models.
Surface activity of tear fluid in patients with primary Sjögren's syndrome
Authors: Zhao Jiang , Manthorpe Rolf , Wollmer Per
Published: March 2003

Rupture of the preocular tear film leads to formation of a dry spot on the cornea with ocular irritation and symptoms of dry eye. One of the factors determining the stability of the tear film is its surface activity. The purpose of this study was to examine the surface activity of tear fluid from patients with Sjögren's syndrome. Tear fluid was sampled from the eyes of 16 patients with primary Sjögren's syndrome. The surface activity of the sample was measured on a Wilhelmy balance. Maximum and minimum surface tension was 72·2 ± 1·7 and 52·9 ± 7·4 mN m−1, respectively. Corresponding values in a previously studied group of normal subjects were 71·5 ± 1·3 and 46·6 ± 3·8 mN m–1, respectively. The difference in minimal surface tension was statistically significant (P<0·001). Reduced surface activity may be caused by dysfunction of the Meibomian glands and suggests a mechanism for causing the symptoms of dry eyes.
Repeatability of measurements of oxygen consumption, heart rate and Borg's scale in men during ergometer cycling
Authors: Wergel‐Kolmert Ulla , Wisén Anita , Wohlfart Björn
Published: March 2003

The coefficient of repeatability (COR), expressed as 2 SD of differences, was calculated between two measurements of oxygen consumption ( ), heart rate (HR) and rating of perceived exertion (RPE) during ergometer cycling by men. The two sets of measurements were performed 5 to 6 weeks apart. Nineteen healthy men performed an incremental maximal exercise test on an ergometer cycle. The load started at 50 W and increased by 5 W 20 s−1 until exhaustion was reached. At 40% of the individual maximum load of the pretest, the load was kept constant for 4 min in order to reach steady state. Gas measurements were recorded continuously by computerized instrumentation. The HR was monitored with electrocardiography (ECG) and the perceived exertion was evaluated using Borg's scale. The COR of

at sub‐maximal load was 14% and at maximum load 11%. The values in absolute figures were 209 and 332 ml min−1. The corresponding COR of the HR was 16% at sub‐maximum load and 6% at maximum load, and an evaluation of the perceived exertion yielded CORs in absolute values of 4·8 and 1·3, respectively. The COR for

, HR and ratings of perceived exertion when cycling on an ergometer cycle thus indicate a better agreement between the measurements at maximum load. The COR of the heart at sub‐maximal loads must be kept in mind when using HR for estimation of

. The reported findings should be considered when using tests on an ergometer cycle for evaluating exercise capacity.
Interferential therapy: lack of effect upon experimentally induced delayed onset muscle soreness
Authors: Minder P. M. , Noble J. G. , Alves‐Guerreiro J. , Hill I. D. , Lowe A. S. , Walsh D. M. , Baxter G. D.
Published: March 2003

This study was designed to assess the analgesic effects of interferential therapy (IFT) on experimentally induced muscular pain under randomized, double‐blind, placebo‐controlled conditions. After ethical approval and written consent were obtained, 40 healthy human volunteers (20 males:20 females) aged 18–25 years were recruited and randomly assigned to one of four experimental groups (n=10 per group: male=female): IFT 1, IFT 2, control or placebo. Delayed onset muscle soreness (DOMS) was induced in the elbow flexors of the non‐dominant arm of each subject using a single bout of eccentric exercises to exhaustion. Measurements of isometric peak torque, resting angle, mechanical pain threshold and visual analogue scales were performed at set time points. Treatment was applied for 30 min daily over the biceps brachii muscle, for five consecutive days, according to group allocation. IFT 1 received 10–20 Hz, whilst subjects in IFT 2 were treated with 80–100 Hz (bi‐pole; carrier frequency: 4 kHz; pulse duration: 125 μs). For the placebo group, the procedure was identical to that in the active treatment groups; however, no interferential current was delivered. The control group received no treatment. No significant between group difference was identified at any time point (P≥0·14). However, some inconsistent, yet significant differences in daily treatment effects, interactive effects and effects over time were detected. Based on the results of this study it can be concluded that application of IFT at the parameters used here, had no overall beneficial effect on DOMS.
Comparison of ventilation/perfusion scintigraphy and helical CT for diagnosis of pulmonary embolism; strategy using clinical data and ancillary findings
Authors: Bajc Marika , Albrechtsson Ulf , Olsson Carl‐Gustav , Olsson Berit , Jonson Björn
Published: March 2003

Study objective: To address the question whether ventilation/perfusion scintigraphy (SCINT) or helical computed tomography (CT) should be the first hand method for diagnosis of pulmonary embolism (PE).

Setting: Departments of radiology, nuclear medicine and internal medicine of a large university hospital.

Patients: During 3 years all 128 patients examined for PE with both methods were analysed. The strategy of interpretation behind original clinical reports, i.e. clinical CT and clinical SCINT, was based upon basic criteria for PE, ancillary findings and information from the referring doctor and from previous examinations. Reviewed SCINT and CT reports were obtained from experts in each field blinded to clinical and laboratory data. The findings with respect to PE were classified as no PE, PE or non‐diagnostic. Other pathology than PE was described. A final diagnosis serving as reference was based upon CT, SCINT and other information including clinical follow for 6–24 months.

Methods: Planar SCINT was made with ventilation always preceding perfusion. CT was made with contrast injection using 3 mm collimation and table feed of 3 mm s−1.

Results: PE was diagnosed in 32 patients. For clinical and reviewed SCINT sensitivity was 91 and 97%, specificity 96 and 100% and rate of non‐diagnostic findings 10 and 9%, respectively. For clinical and reviewed CT sensitivity was 81 and 78%, specificity 99 and 100% and non‐diagnostic findings was observed in 8 and 1%, respectively. In patients with PE, concordant positive results were obtained with both modalities in 23 of 32 patients (72%).

Conclusion: SCINT remains the first hand method because its high sensitivity, general feasibility, low radiation burden and low rate of non‐diagnostic findings in our setting. CT is indispensable when SCINT is not available or its result non‐diagnostic.
On‐ and off‐responses of heart rate to exercise – relations to heart rate variability
Authors: Javorka Michal , Žila Ivan , Balhárek Tomáš , Javorka Kamil
Published: March 2003

During physical exercise, heart rate (HR) increases by parasympathetic withdrawal and increase of sympathetic activity to the heart. HR variability (HRV) in time and frequency domains provides information about autonomic control of the cardiovascular system. Non‐linear analysis using the Poincaré plot method is able to reveal supplementary information about cardiac autonomic control. The aim of this study was to determine the association between HRV parameters, the initial increase of HR at the onset of exercise (on‐response) and HR decrease in the recovery phase after acute exercise (off‐response). HR was continuously monitored in 17 healthy male subjects (mean age: 20·3 ± 0·2 (SEM) years) at rest (25 min supine; 5 min standing), during exercise (8 min of step test at 70% of maximal power output) and in the recovery phase (30 min supine). HRV analysis in time and frequency domains and evaluation of the Poincaré plot measures (length, widths) were performed on selected segments of HR time series. HR on‐ and off‐responses were quantified using an exponential curve fitting technique. The time constants Ton and Toff, representing the rate of on‐ and off‐responses to exercise, were computed. Postexercise HRV indices and time constant of on‐response – Ton – to exercise were negatively correlated. From preexercise HRV indices, only Poincaré plot parameters were correlated with Ton. No correlation between HRV indices and parameters of off‐response was found. In conclusion, preexercise HRV parameters are not closely correlated with the rate of cardioacceleration at the onset of exercise and cannot predict the rate of HR recovery. On the other hand, postexercise HRV parameters are related to the rate of initial adjustment of HR to exercise referring to the importance of rapid HR on‐response for a faster recovery after exercise.
Preserved bronchial dilatation after salbutamol does not guarantee protection against bronchial hyperresponsiveness
Authors: Sjöswärd Kerstin Naidu , Josefsson Martin , Ahlner Johan , Schmekel Birgitta
Published: March 2003

Racemic salbutamol, a β2‐adrenoceptor agonist used for dilatation of airways, has recently been shown to induce lessened relaxation of bronchial smooth muscle and partial loss of bronchoprotection, seen as increased hyperresponsiveness, after regular treatment. The racemate undergoes stereo‐selective disposition, giving higher plasma levels of S‐salbutamol than that of bronchodilating R‐salbutamol, thus raising S : R ratios after repeated administration. Our aim was to evaluate whether increased bronchial hyperresponsiveness (BHR) could be found even after 1 day of repeated salbutamol inhalations, with β2‐receptor‐induced bronchial smooth muscle relaxation remaining and whether this would be associated with plasma levels of either enantiomer. Fifteen patients with stable asthma, aged 19–54 years, were included in a randomized, cross‐over study. An indirect bronchial challenge method was used [voluntary isocapnic hyperventilation of cold air (IHCA)], and airway condition tested by means of impulse oscillometry. Racemic salbutamol was inhaled three times during a 6‐h period. IHCA was performed and plasma concentrations of enantiomers were measured 4 h after the last dose. Tests were also performed without preceding drug treatment. β2‐Agonist‐produced bronchial dilatation and protection persisted in the majority of the 15 patients 4 h after repeated inhalations of salbutamol during 1 day. In only two of the 15 patients we could trace increased BHR after salbutamol. Neither dilatation nor protection could be linked to plasma levels of either R‐ or S‐salbutamol. The underlying mechanisms of BHR remain unknown and are dissociated from β2‐receptor‐mediated dilatation.
The Importance of the Water Conservation Areas in the Everglades to the Endangered Wood Stork (Mycteria americana)
Authors: Bancroft G. Thomas , Hoffman Wayne , Sawicki Richard J. , Ogden John C.
Published: March 2003

During 1985–1989, numbers of the endangered Wood Stork (Mycteria americana) in the Water Conservation Areas of the Everglades, Florida, showed an annual peak in February or March of 1233 to 7874 birds. The annual maxima are significantly greater in dry years than in wet years (P < 0.05). Most storks are nonbreeders and are found foraging in open habitats along the eastern and southern parts of Conservation Area 1 and Conservation Area 2A and along the west‐central side of Conservation Area 3A. In dry years, large numbers move into the southern half of Conservation Area 3A. We estimated that in spring, the total southeastern United States population of Wood Storks is between 14,000 and 20,000 individuals. The annual maxima of the water conservation areas were at least 8% to 10% of the total southeastern U.S. population in wet years and possibly as much as 55% in dry years. The Water Conservation Areas appear to be critical foraging habitat for wintering storks, especially during drought years when most of the rest of south Florida is dry. Changes in the management of these areas could have a major impact on the status of storks throughout the southeastern United States.
Forage Quality as a Limiting Factor for Cattle Grazing in Isolated Dutch Nature Reserves
Authors: Bokdam Jan , De Vries Wallis Michiel F.
Published: March 2003

Most Dutch nature reserves are small, isolated fragments of former semi‐natural landscapes. Cattle and other large domestic herbivores are being increasingly (re)‐introduced in nature reserves as a tool for vegetation management and as an ecological substitute for extinct wild herbivores. The performance of cattle in these single‐landscape areas appears to be seriously limited by a combination of inadequate forage and habitat isolation. Animals cannot move seasonally between different landscape types. We compared the forage quality of three landscape types. Quality parameters included organic matter digestibility and contents of macronutrients: nitrogen (N), phosphorus (P), potassium (K), sodium (K), calcium (Ca), and magnesium (Mg). In landscapes of low fertility, insufficient concentrations were found of P, Na, Ca, and Mg. However, because the assumed maintenance requirements for cattle are possibly overestimated, the prediction of deficiencies for the animals remains uncertain. In landscapes of intermediate fertility, the level of Na is deficient for most of the year. Winter digestibility is inadequate in vegetation remaining ungrazed until winter, whereas in grazed vegetation the quantity of easily‐digestible forage is insufficient to satisfy quantitative intake requirements. In landscapes of high fertility, the mineral supply is adequate, but low digestibility in winter will lead to energy shortage. Insufficient forage quality seems to preclude sustained year‐round grazing in each of the three landscape types. Single‐landscape areas constitute seasonal habitats for cattle, suitable for summer or winter grazing only. Connection of complementary landscapes is essential to create complete year‐round habitats for cattle and other large herbivores. The restoration of linkage of summer and winter range by the creation of corridors is the most natural solution. Seasonal grazing with controlled migration or transportation of the herd between winter and summer range reserves is a second‐best alternative involving less interference than year‐round grazing with supplementation.
Mitochondrial DNA Variability of the Gray Wolf: Genetic Consequences of Population Decline and Habitat Fragmentation
Authors: Wayne Robert K. , Lehman Niles , Allard Marc W. , Honeycutt Rodney L.
Published: March 2003

The gray wolf is a large, highly mobile predator whose original geographic range included most of the Northern Hemisphere. High rates of genetic exchange probably characterized even distantly‐separated populations in the past, but recent population declines and habitat fragmentation have isolated previously contiguous populations, especially in the Old World. We examine mitochondrial DNA (mtDNA) variability among twenty‐six populations of wolves from throughout their geographic range. We find eighteen mtDNA genotypes in gray wolves, seven of these are derived from hybridization with coyotes, four are confined to the New World, six are confined to the Old World and one is shared by both areas. Genetic differentiation among wolf populations is significant but small in magnitude. In the Old World, most localities have a single unique genotype, whereas in the New World several genotypes occur at most localities and three of the five genotypes are nearly ubiquitous. The pattern of genetic differentiation in the gray wolf contrasts with that of another large, highly vagile canid, the coyote, in which genetic differentiation among populations is not significant even among widely separated localities. We suggest that the difference between these two species reflects the rapid, recent increase in coyote numbers and expansion of their geographic range, and the coincident decline in gray wolf populations. Apparent genetic differences among extant wolf populations may be a recent phenomenon reflecting population declines and habitat fragmentation rather than a long history of genetic isolation.
The Sweetwater Rattlesnake Round‐Up: A Case Study in Environmental Ethics
Authors: WEIR JACK
Published: March 2003

Abstract: This study is an ethical analysis and evaluation of an ecologically and environmentally intrusive social phenomenon, the Sweetwater (Texas) Jaycees Rattlesnake Round‐Up, an annual event that results in the killing of thousands of rattlesnakes (Crotalus atrox). The largest and most publicized of several such festivals in the United States, the Sweetwater Round‐Up has developed into a huge community extravaganza with lucrative benefits to the local economy. After overviews of the Round‐Up and of recent biological research, the main reasons justifying the practice are evaluated from both a local and environmental perspective. Because the annual take has remained high, the proponents claim that the Round‐Ups are not reducing the rattlesnake population but are in fact “helping the balance of nature.” Although probably false due to lost reproductive potential, this claim cannot be decisively refuted due to a lack of reliable scientific data. Therefore, recommendations are made for restructuring the rattlesnake hunt to obtain scientifically credible data. Paramount is that the time span and territory be limited, because otherwise conclusions based on annual take cannot be made. Recommendations are also presented for conducting additional research and for limiting the ecological impact of the festival while at the same time preserving its economic and social benefits.
Do Appalachian Herbaceous Understories Ever Recover from Clearcutting?
Authors: DUFFY DAVID CAMERON , MEIER ALBERT J.
Published: March 2003

Abstract: Life history characteristics of many herbaceous understory plants suggest that such species recover slowly from major perturbations such as clear cutting. We examined herbaceous cover and richness in the understories of nine primary (“old‐growth”) forests in the southern Appalachian Mountains and of nine comparable secondary forests, ranging in age from 45 to 87 years since clear cutting. Neither cover nor richness increased with age in the secondary forests. This suggests three possibilities: (1) that recovery is so slow or variable among sites that 87 years is insufficient time to detect it; (2) that such forests will never recover to match remnant primary forests because climatic conditions are different today than when the forests became established; or (3) that herbaceous plants colonize pit and mound microtopography caused by the death of trees, so that recovery must await the growth, death, and decomposition of the trees of the secondary forest. Whatever the mechanism, herbaceous understory communities in the mixed‐mesophytic forests of the Appalachians appear unlikely to recover within the present planned logging cycles of 40–150 years, suggesting a future loss of diversity of understory herbaceous plants.
Genetic Variation and Population Structure of Red‐cockaded Woodpeckers
Authors: STANGEL PETER W. , LENNARTZ MICHAEL R. , SMITH MICHAEL H.
Published: March 2003

Abstract: Our objective was to survey genetic variability and examine population structure in the endangered Red‐cockaded Woodpecker, a species whose distribution has been fragmented by land‐use patterns. Sixteen presumptive gene loci were resolved from feather pulp of nestlings and adults from 26 populations rangewide. Mean heterozygosity in the Red‐cockaded Woodpecker was 7.8% and ranged from 3.1%–10.3% across populations. Heterozygosity was significantly but weakly associated with population size; this association was dependent on low heterozygosity in two small populations. The percentage of polymorphic loci and mean number of alleles per locus were also positively correlated with population size. Relative to other species of birds, there is a large among‐population component of genetic variance (Fst= 0.14). Genetic distance among populations increased with geographic distance. Although heterozygosity is reduced in some small populations, most exhibit “normal” levels. Small populations should therefore not be considered “lost causes” from the genetic standpoint. Small populations are important as reservoirs of unique genetic combinations and to help facilitate gene flow among larger populations.
The Evolution of the U.S. National Wildlife Refuge System and the Doctrine of Compatibility
Authors: Curtin Charles G.
Published: March 2003

This paper reviews the history and evolution of the United States National Wildlife Refuge System, perhaps the largest and oldest wildlife conservation system in the world. The refuge system is guided by the doctrine of compatibility, which permits only those uses on a refuge which are “compatible with the purposes for which the refuge was established.” Memoranda and documents spanning the last 100 years were examined, and key refuge personnel interviewed, to understand the historical basis for current refuge policies. Topics of particular importance were the origins of the compatibility doctrine, the origin and meaning of the sanctuary concept, and the means by which refuges were established.

Through time, the refuge system has shifted from a policy of strict protection of wildlife to a policy of integrating public uses of refuges. The doctrine of compatibility has evolved to facilitate public use of wildlife refuges. Increasingly, the needs for recreation and resource use have interfered with the purposes far which refuges were established. A legislative solution may be needed to ensure that these areas are protected and remain viable reserves for wildlife and natural communities.

The sustained conservation of reserve areas often represents a delicate balance between political constraints and biological realities. The examination of the National Wildlife Refuge System not only has ramifications for North American conservation, but illustrates many of the problems and pitfalls facing conservation and land management worldwide.
Are Declines in North American Insectivorous Songbirds Due to Causes on the Breeding Range?
Authors: Böhning‐Gaese Katrin , Taper Mark L. , Brown James H.
Published: March 2003

Previous studies have reported a recent decline in breeding populations of migratory songbirds in eastern and central North America. Several explanations have been suggested: deforestation on the wintering grounds in the tropics and habitat loss, increased predation pressure, and increased cowbirds parasitism on the breeding range. We used these factors to assign 47 species of insectivorous passerines to groups with contrasting vulnerability, and then used the North America Breeding Bird Survey to analyze population trends in these groups on a large continental scale. Variables indexing susceptibility to predation on the breeding ground were most strongly correlated with population trends form 1968 to 1987. During the period from 1978 to 1987, migratory status was also significantly associated with population trends long‐distance migrants to the neotropics exhibited a small, nonsignificant decreasing trend, whereas residents and short‐distance migrants increased strongly. During the same time period, the group of species with low nest location, open nest, and high cowbird parasitism declined significantly. Although it is difficult to separate the effects of multiple factors, our analyses suggest that predation on the breeding ground in North America has played a larger role in the decline of migratory songbirds than deforestation on the wintering grounds in the tropics.
Population Viability Analysis for a Small Population of Red‐Cockaded Woodpeckers and an Evaluation of Enhancement Strategies
Authors: Haig Susan M. , Belthoff James R. , Allen David H.
Published: March 2003

We performed a series of population and pedigree analyses to examine the viability of a small Red‐cockaded Woodpecker (Picoides borealis) population located at the Savannah River Site, in Barnwell and Aiken counties of South Carolina. The population’s existence and future survival are precarious. As few as four individuals, including just one breeding pair, comprised this population in 1985. Now, primarily because of experimental transformation of birds from other areas, the population has increased to 25. As of 1990, genealogy pedigree analysis showed that the respective contribution of 14 founders to the extant population has not been equal. Founder gender equivalents are low (5.4) but could reach 9.2 if poorly‐represented founders were to produce offspring. The fraction of founder gene diversity retained in the current population is 0.91. Successful recovery strategies would ensure 95% probability of population survival while maintaining 90% heterozygosity for 200 years. Viability analyses indicated that, depending on relative effects of inbreeding depression and stochastic environmental events, the Savannah River Site population has a 68–100% chance of extinction during this period. Annual translocation into the population of at least three females and two males for a 10‐year period will achieve a 96% probability of survival for 200 years. Even with translocation of numerous males and females per year (up to 50 of each), the 90% heterozygosity goal may not be achieved. We discuss recommendations for choosing individuals for translocation logistical constraints on achieving recovery objectives, and limitations of our modeling approach.
The Impact of Brown‐Headed Cowbird Parasitism on Populations of the White‐Crowned Sparrow
Authors: Trail Pepper W. , Baptista Luis F.
Published: March 2003

Brown‐headed Cowbirds, Molothrus ater, are brood parasites on many species of North American Passerines. Cowbird parasitism is frequently cited as a contributing factor in the decline of United States passerine populations, based on three lines of evidence. First, range expansion and population increases by Cowbirds in this century are dramatic and well documented. Second, increasing rates of parasitism have been discovered in a variety of host species populations. Finally, direct negative effects of parasitism on certain vulnerable species notably Kirtland’s Warbler, Dendroica kirtlandii, have been demonstrated. It remains unproven, however, that Cowbirds have significant negative effects on more abundant and widely‐distributed hosts.

We report here on the impact of Cowbird parasitism on populations of Nuttall’s White‐crowned Sparrow, Zonotrichia leucophrys nuttalli, in the San Francisco Bay Area. This widespread songbird is now subject to a 40–50% rate of parasitism in San Francisco, an increase from 5% only 15 years ago. Using known mortality and fecundity values, we calculate that this population of White‐crowns cannot maintain its numbers when the parasitism rate exceeds approximately 20%. Present levels of parasitism thus appear to threaten the longevity survival of this adaptable Songbird in the San Francisco Bay Area.
Potential Impact of Mammalian Nest Predators on Endemic Forest Birds of Western Mauna Kea, Hawaii
Authors: Amarasekare Priyanga
Published: March 2003

I used dummy nest experiments to investigate the role of nest predation by introduced mammals asa significant limiting factor for the endangered Palila (Loxioides bailleui) and other endemic birds on the western slope of Mauna Kea. Overall predation rates on dummy nests were extremely low. Rates were comparable to those on actual Palila nests, indicating that dummy nests give a valid representation of the dynamics of nest predation. The black rat (Rattus rattus) was the only important predator. Feral cats (Felis catus) played only a minor role, and there was no evidence to implicate house mice (Mus musculus) as nest predators. Four factors appear to be responsible for the low nest predation rates: (1) only a single species of predator (black rat) is involved; (2) rat densities are extremely low on Mauna Kea; (3) low prey (nest)densities preclude density‐dependent predation, and (4) rats have alternative foods that are more abundant and accessible than arboreal bird nests. Since mammalian predation appears unlikely to have a significant impact on the Palila, other factors must be limiting the abundance of this endangered species.
Conservation in Lake Tanganyika, with Special Reference to Underwater Parks
Authors: Coulter G. , Mubamba R.
Published: March 2003

Lake Tanganyika is outstanding among lakes because of the intrinsic value of its fauna and the significance of its natural resources. Reconciliation of resource exploitation and conservation is essential because of changes in the lake environment caused by human activities. Important new initiatives to shape national environmental policies for the lake are taking place. Regional cooperation is required for major lakewide studies, especially in lake circulation and the prevention of pollution, and in adjustment of fisheries objectives to meet conservation as well as economic goals. Basic conservation aims proposed are (1) avoidance of gross changes in natural communities in the lake in general, and (2) retention of the fauna in some parts in an unexploited state, as in underwater parks. Early strategies suggested are the extension of four existing wildlife land parks further into the lake to form underwater parks, and reconnaissance of other potential park sites. Initial ecological and social surveys conducted from the four parks would provide baseline data for management. Underwater park boundaries should as far as possible be determined on an ecological basis to encompass entire local distributions of species populations. A case of alternative boundaries is examined for the Nsumbu Park. Other important planning considerations are the multi‐use of parks in addition to fundamental conservation, such as tourism, sport fishing, and specific traditional lake and land uses. Regional cooperation between parks will be important for tourism.
Modeling Effects of Land Management in the Brazilian Amazonian Settlement of Rondônia
Authors: Dale Virginia H. , O'Neill Robert V. , Southworth Frank , Pedlowski Marcos
Published: March 2003

The socioeconomic and ecological aspects of landuse change are interrelated, especially in the Brazilian Amazon, where immigrants are rapidly cutting the forest to establish farms. A computer simulation has been developed that projects land‐use changes, carbon release, and the time a family can remain on a farm lot as a function of initial soil and vegetation conditions, market and road infrastructure, and decision variables. The model simulates extremes of land‐use practices and typical land‐use conditions for central Rondônia, Brazil. Typical land‐use practices in Rondônia are based on published accounts of farmers’ activities. The most severe practices are defined based on extreme land management conditions along the Transamazon Highway. The best land‐use practices are innovative farming techniques that use a diversity of perennial crops. Model projections using the typical land‐use scenario produce changes in land cleared, carbon release, and farmer turnover rates representative of central Rondônia, based on interviews with 87 farmers. Results from both the model projections and the interview data show that farmers who have been on the lots a decade have cleared about half of the lot. The most striking result is the similarity in the typical and worst‐case scenarios over the 40‐year projection period in the percentage of land cleared and carbon released and in the number of families on the farm lots and abandoning the lots over time. Model results from the best‐case scenario compare well to the three farmers out of 87 interviewed who practice innovative farming. In both cases, farmers who have been on their land an average of eight years have deforested less than 20% of the lot. Spatial indices of fractal dimension and contagion are used to quantify the effects of the different land‐management practices. Changes in the fractal index over the 40 years of projected land management demonstrate the decrease in complexity as a forested region becomes dominated by agriculture for the typical and worst‐case scenarios. Low values of the contagion index indicates that a heterogeneous mix of land uses is retained with the best‐case scenario. These results suggest that crop diversity and nontraditional techniques provide both a social and environmental improvement over the other scenarios: the people are able to maintain themselves on the land, less carbon is released, and the land maintains a mix of habitat types. The model results illustrate that both social and environmental effects of land‐management practices need to be considered.
The Conflict between Wildlife and Local People Living Adjacent to Protected Areas in Tanzania: Human Density as a Predictor
Authors: Newmark William D. , Manyanza David N. , Gamassa Deo‐Gratias M. , Sariko Hashan I.
Published: March 2003

A questionnaire survey was conducted in Tanzania of 1396 local people living adjacent to Arusha, Kilimanjaro, Tarangire, Lake Manyara, and Mikumi National Parks and the Selous Game Reserve. Over 71% of local people surveyed reported problems with wildlife. The relative frequency of reported conflict with wildlife was significantly and inversely related to human density on lands adjacent to a protected area. Of those local people who reported having problems with wildlife, 86% reported crop damage, while 10% reported the killing of livestock and poultry. The problematic wildlife species also varied significantly with human density. Large animals were more problematic at low human densities, while small animals were more problematic at high human densities. Local people were generally less effective in controlling small‐bodied species than large‐bodied species. The relative frequency of reported success in controlling wildlife varied significantly with human density and was bimodal: local people were less effective in controlling wildlife at lower and higher human densities. This bimodal relationship suggests that, even if all protected areas in Tanzania were abolished, local people would continue to experience problems with wildlife at high human densities. To minimize the conflict between wildlife and local people, land uses associated with low human density that are non‐attractive to wildlife should be encouraged on lands adjacent to protected areas in Tanzania.
Managing Biodiversity in a Forestry Environment
Authors: Kuusipalo Jussi , Kangas Jyrki
Published: March 2003

In forest management and other land‐use planning, ecological, social, and economical demands often conflict. Forest planning in particular has been biased towards maximizing economic output while disregarding the ecological effects of forestry practices. In this paper we present an approach for taking biological diversity into account in strategic forest management planning. We used the Analytic Hierarchy Process (AHP) method for resource allocation and priority setting. We carried out a case study, whereby a set of management strategies was evaluated in order to identify the strategy which best fulfills the requirement of maintaining biological diversity while at the same time yielding a reasonable income from timber production. We discuss applicability of the approach in solving different forest management and conservation planning problems, as well as in assessment of ecological impacts.
The Impact of Variation in Stopover Habitat Quality on Migrant Rufous Hummingbirds
Authors: Russell Robert W. , Carpenter F. Lynn , Hixon Mark A. , Paton David C.
Published: March 2003

We examined the impact of variation in habitat quality on migrating Rufous Hummingbirds (Selasphorus rufus) in the California Sierra Nevada. As do other migratory species, these birds depend on “stopover” habitats en route for feeding and replenishing depleted energy stores. During seven years of study, the quality of the stopover habitat (assessed in terms of the density of nectar food resources) varied widely due to natural variation in flowering. In years when stopover habitat quality was poor, incoming body masses were low and stopover durations were long. Population densities of migrant hummingbirds at the study site were coupled to habitat quality both within and among years. These observations demonstrate important effects of stopover habitat variation on the physiological, behavioral, and population ecology of migrating hummingbirds. High‐quality stopover habitats are critical links between breeding and wintering areas for many species, and their preservation should be considered an essential component of strategies aiming to conserve migratory bird populations.
Island Extinction Rates from Regular Censuses
Authors: Rosenzweig Michael L. , Clark Colin W.
Published: March 2003

Regular censuses conducted over a long time allow the calculation of both extinction and immigration rates. We present formulae for estimation of those rates. We use them on bird censuses of three British islands. These formulae improve on previous estimators of extinction but reaffirm that smaller populations have a higher probability of becoming extinct. On the other hand, they suggest no correlation between extinction rate and either body size or migratory status among birds.
Ecological Costs of Livestock Grazing in Western North America
Authors: Fleischner Thomas L.
Published: March 2003

Livestock grazing is the most widespread land management practice in western North America. Seventy percent of the western United States is grazed, including wilderness areas, wildlife refuges, national forests, and even some national parks. The ecological costs of this nearly ubiquitous form of land use can be dramatic. Examples of such costs include loss of biodiversity; lowering of population densities for a wide variety of taxa; disruption of ecosystem functions, including nutrient cycling and succession; change in community organization; and change in the physical characteristics of both terrestrial and aquatic habitats. Because livestock congregate in riparian ecosystems, which are among the biologically richest habitats in arid and semiarid regions, the ecological costs of grazing are magnified in these sites. Range science has traditionally been laden with economic assumptions favoring resource use. Conservation biologists are encouraged to contribute to the ongoing social and scientific dialogue on grazing issues.
The Biopolitics of the Mt. Graham Red Squirrel (Tamiasciuris hudsonicus grahamensis)
Authors: Warshall Peter
Published: March 2003

This essay presents (1) a short status summary on the population biology of the Mt. Graham red squirrel on the Pinaleño Mountains, Arizona; (2) a biopolitical history of the controversy surrounding the Mt. Graham red squirrel, the Endangered Species Act (ESA), and the astronomical consortium that has constructed two telescopes within the squirrel's critical habitat; and (3) a discussion of specific biopolitical issues related to the squirrel's taxonomy, minimal viable habitat, critical habitat, population viability analysis, risk management, and Congressional actions to by‐pass its own laws. The biopolitical history shows how specific administrative actions within the U.S. Forest Service and the U.S. Fish and Wildlife Service and special interest politics by the Arizona Congressional delegation and the University of Arizona prevented an accurate assessment of the status of the Mt. Graham red squirrel and implementation of alternatives to insure its survival and recovery. Conservation biology can influence management decisions when not overridden by special‐favor politics. To improve the influence of the science of conservation biology, I recommend that the ESA language protecting isolated populations (Section 3) remain intact and that the ESA make a legal distinction (Section 4) between minimal viable habitat and critical habitat. To improve the application of the ESA, I recommend that Congress require committee hearings before it can exempt a project from federal environmental laws; that fraudulent Biological Opinions automatically trigger a complete review of long‐term viability; that conservation biologists prepare a handbook for the Fish and Wildlife Service on risk assessment techniques; that all data and analyses within the Biological Opinion include a ranking by their statistical and biological certainty as well as a worst‐case scenario; and that each Biological Opinion be certified as risk averse.
Avian Species Richness in Different‐Aged Stands of Riparian Forest Along the Middle Rio Grande, New Mexico
Authors: Farley Greg H. , Ellis Lisa M. , Stuart James N. , Scott Norman J.
Published: March 2003

Riparian forests are important for maintaining vertebrate species richness in the southwestern United States, but they have become restricted in distribution due to both historical and current management practices. In order to counteract continued loss of this habitat, several mitigation programs were developed in the middle Rio Grande Valley of New Mexico. Three areas ranging from 50 to 140 ha were revegetated with native trees using pole planting and cattle exclosures, and changes in vegetation structure were quantified after 2, 3, and 5 years of growth. As expected, the older site contained the most heterogeneous mix of plant species and the greatest structural diversity. We compared year‐round avian use of the revegetated sites with a mature cottonwood forest site of approximately 30 years of age. As the revegetated sites matured and salient habitat features changed, the population dynamics of individual avian species and patterns of guild structure varied. The older revegetated sites showed a greater similarity to the mature cottonwood site, suggesting that reclamation efforts established quality riparian habitats for birds in as little as 5 years. The revegetated sites appeared especially important for Neotropical‐migrant birds. We suggest that a mosaic of riparian woodlands containing mixtures of native tree and shrub species of different size classes is necessary to maintain avian species richness in the middle Rio Grande drainage, and probably throughout the southwestern United States.
Preservation of Primary Forests in the Luquillo Mountains, Puerto Rico
Authors: Lugo Ariel E.
Published: March 2003

The Caribbean National Forest, a National Forest under the jurisdiction of the U.S. Forest Service and a United Nations Educational, Scientific, and Cultural Organization Biosphere Reserve, contains the only primary tropical forests in Puerto Rico. The planning for future uses of the Caribbean National Forest has been controversial and serves as a case study of the application of federal regulations designed for continental temperate zones to insular tropical conditions. This article contains a description of the environmental and historical setting of the Caribbean National Forest and presents arguments for and against the preservation of its primary forests. Given the history of custodial management of the forest by the U.S. Forest Service, it appears unlikely that the agency will advocate conversion of the only primary tropical forests under U.S. Government jurisdiction in order to satisfy requirements of the National Wilderness Act and/or the National Forest Planning Act. The planning, management, and conservation of the Caribbean National Forest can be a model for such activities elsewhere in the Caribbean and the American tropics but only if it demonstrates a balance between intensive use of suitable stands and absolute protection of primary forests.
Forest Management Patterns in the Floodplain of the Amazon Estuary
Authors: Anderson Anthony B. , Magee Pennie , Gély Anne , Gonçalves Jardim Mário Augusto
Published: March 2003

In the Amazon basin, few studies have focused on environmentally sound land‐use alternatives that are linked to markets. This paper analyzes land uses carried out by traditional inhabitants (ribeirinhos) on three islands in the Amazon estuary. Management of the native floodplain forest is the most extensive form of land use on these islands. Such management varies in response to local economic and ecological conditions but invariably targets key nontimber forest resources destined for local markets, requires minimal input of labor and capital, and maintains a considerable stock of biotic resources. While restricted to a specific forest type, this form of land use is associated with relatively high population densities and, if supported by appropriate development policies, could provide an environmentally sound land‐use alternative for hundreds of thousands of rural inhabitants of Amazonia.