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PubMed1996

Myocardial dysfunction after successful resuscitation from cardiac arrest.

OBJECTIVE: To investigate the functional and metabolic changes in the myocardium after successful resuscitation from cardiac arrest. DESIGN: Prospective, randomized, sham-controlled study. SETTING: Animal laboratory at a university center. SUBJECTS: Domestic pigs. INTERVENTIONS: Electric induction of ventricular fibrillation by alternating current delivered to the right ventricular endocardium through a pacing electrode. Electric defibrillation was attempted after an interval of 12 mins of ventricular fibrillation, which included 4 mins of untreated ventricular fibrillation and 8 mins of precordial compression in 13 animals, seven of which were successfully resuscitated. Seven additional animals were randomized to serve as "sham" controls, in which cardiac arrest was not induced. MEASUREMENTS AND MAIN RESULTS: Left ventricular pressure-volume relationships utilizing the conductance method were obtained in conjunction with conventional hemodynamic and metabolic measurements at baseline and during a 6-hr interval after successful cardiac resuscitation. Progressive and striking increases in left ventricular volumes were observed after successful cardiac resuscitation. The end-diastolic volume increased from a prearrest level of 89 +/- 21 mL to a maximum of 154 +/- 53 mL (p<.05) at 360 mins after successful resuscitation. The time-coincident end-systolic volume increased from 54 +/- 21 to 126 +/- 54 mL (p<.05), such that the ejection fraction was reduced from 0.41 +/- 0.10 to 0.20 +/- 0.07 ( p<.05). Ventricular dilation was associated with marked reductions in stroke volume and ventricular work. However, compensatory increases in heart rate maintained cardiac output at levels that sustained adequate systemic oxygen delivery. The slope of the end-systolic pressure-volume relationships progressively decreased from 5.04 +/- 1.88 to 2.00 +/- 0.57 mm Hg/mL (p<.05) at 360 mins after successful resuscitation. The volume intercept at left ventricular pressure of 100 mm Hg increased from 43 +/- 19 to 94 +/- 51 mL (p=.03). Both the decrease in the slope and the increase in the volume intercept were characteristic of progressive impairment in contractile function. The rate of left ventricular pressure decrease was unchanged. Accordingly, no substantial changes in lusitropic properties were identified. Despite large increases in end-diastolic volume, the end-diastolic pressure remained unchanged. CONCLUSION: Postresuscitation myocardial dysfunction in this animal model was characterized by impaired contractile function, decreased work capability, and ventricular dilation.

Animals↗
PubMed1992

Correlates of successful hearing aid use in older adults.

OBJECTIVE: To evaluate whether age, education, functional handicap, degree of hearing loss, amount of hearing and speech recognition gain achieved with hearing aid, locus of control, visual acuity, manual dexterity, number of comorbid diseases, and number of medications predict which elderly individuals with hearing loss are likely to benefit from hearing aids. DESIGN: A logistic regression prediction model for hearing aid benefit was developed on a training set of 89 individuals and verified in a test set of 87 individuals. Hearing aid success was assessed 4 mo after hearing aid adminstration. It was defined by assessing hearing aid satisfaction, functional handicap change post-hearing aid, and number of hours of weekly hearing aid use. SETTING: All patients were elderly male veterans from the Audie L. Murphy Memorial Veterans Hospital. There were no differences in demographic or clinical characteristics in training versus test set individuals. RESULTS: Several variables, including baseline perceived functional handicap, education, number of medications, and age correlated with individual success measures. However, no variables consistently correlated with all success measures. The accuracy of prediction rules for success utilizing the variables ranged from 75 to 88% in the training set, and 54 to 84% in the test set. CONCLUSION: Although certain baseline factors were statistically significantly related to individual measures of successful hearing aid use, no factors were good enough to consistently differentiate successful from unsuccessful hearing aid candidates.

Age Factors↗
PubMed1999

The organization of vocational rehabilitation: the structure of success.

Focusing on vocational rehabilitation goals provides an understanding of the underlying structural and behavioural factors affecting successful employment outcomes. Two types of vocational centres having contrasting rehabilitation employment orientations are examined. Both types have similar end goals but organizational structures shaping divergent means toward the gainful employment of disabled persons. Utilizing a split sample of 14 vocational rehabilitation programmes in Israel, 7 sheltered and 7 supported programmes, a structured questionnaire of key administrative personnel and employees was generated. Success was based on six consensus measures. Clear differences between administrative, organizational and programme goals emerge, which affect goal priority and source of success measurement. Employing regression models, three keys to success are detected which stress the interplay between internal and external organization reference criteria in affecting success attainment. The results suggest that the organization of vocational rehabilitation has a direct impact on rehabilitation success.

Adult↗
PubMed2000

Mortality after successful transcatheter arterial embolization in patients with unstable pelvic fractures: rate of blood transfusion as a predictive factor.

BACKGROUND: To determine the factors predictive of mortality in patients with unstable pelvic fractures after successful transcatheter arterial embolization. METHODS: A retrospective study of pelvic fractures between May of 1995 and April of 1998 was performed. Of 507 patients, 17 who were unstable underwent embolization. The success rate of embolization and the mortality rate after successful embolization were reviewed. Predictive factors (contrast medium extravasation, initial blood pressure, Injury Severity Score, timing of external fixation, time to angiography, volume of blood transfusion, rate of blood transfusion) of the final outcome were statistically analyzed. RESULTS: Embolization was 100% effective in stopping pelvic hemorrhage. The mortality of patients treated successfully with embolization was 17.6%. Among the predictive factors analyzed, only the rate of blood transfusion before embolization, 11.3 +/- 11.0 units/h (death) versus 3.2 +/- 1.9 units/h (survival) showed statistical significance with an odds ratio of 1.62 (95% confidence interval, 1.07-2.46). CONCLUSION: The success rate of embolization was 100% in stopping arterial hemorrhage of unstable pelvic fractures. The survival rate after successful embolization was 82.4%. Patients who had rapid blood transfusion before embolization had a poor final outcome. The risk of dying increased by 62% for every 1 unit/h increase of transfusion rate.

Adolescent↗
PubMed1984

Classification criterion for success in the treatment of convergence insufficiency.

Using data collected from a retrospective study of the records of 110 patients diagnosed as having convergence insufficiency, a model has been developed which allows the classification of a patient into one of two categories of success (total or partial/none) on the basis of an initial examination. The subjects were treated with orthoptics and classified into either the total success group (no objective or subjective visual difficulties) or the partial/no success group. Stepwise discriminant analysis was used in the data reduction phase in which 6 of 14 possible variables were selected which best explained the variation in the degree of success. These six variables were: (1) the AC/A ratio; (2) the negative vergence blur value at 40 cm; (3) the recovery value of the positive vergences at 6 m; (4) the break value of the positive vergence at 6 m; (5) the amplitude of accommodation; and (6) the frequency of the deviation. Subjects were more likely to be successful when 1, 2 and 3 were high, 4 and 5 were low, and the deviation was latent. Discriminant analysis using these six variables allowed 25 of 33 (76%) of the patients to be correctly classified in terms of their success. The application of the model for classifying patients with convergence insufficiency is presented and briefly discussed.

Accommodation, Ocular↗
PubMed2000

Factors predicting the long-term success of maintenance cyclosporine monotherapy after kidney transplantation.

BACKGROUND: The theoretical aim of maintenance cyclosporine monotherapy (mCsA) after kidney transplantation is to reduce the incidence of the metabolic complications of corticosteroids and to minimize the adverse effects of excessive long-term immunosuppression. This study was performed in low-immunological-risk cadaveric kidney transplant recipients to evaluate the risks and benefits of mCsA and the long-term graft survival, and to determine the factors predicting success of this policy. METHODS: The multicenter retrospective study was conducted in 329 Caucasian patients receiving mCsA out of 728 first cadaveric kidney transplant recipients. The inclusion criteria were: HLA antibodies < or =25%, serum creatinine <200 micromol/L, and no rejection or only one rejection episode. At the end of the study, we compared the group of patients successfully treated with mCsA (successful group) with those requiring additional immunosuppressive agents (unsuccessful mCsA group). RESULTS: Overall patient and graft survival rates for the 728 first cadaveric graft were 92% and 64%, respectively, at 8 years. Out of 329 patients enrolled in mCsA, 240 were maintained on this treatment and 89 were withdrawn (3 deaths, 18 graft losses, 68 functional grafts). The 8-year graft survival in the 329 enrolled mCsA patients was 84%, 95% in the successful mCsA group, and 70% in the unsuccessful mCsA group. Multivariate analysis showed that the factors predicting success of mCsA were: donor age <40 years (P = 0.001), serum creatinine at mCsA initiation <125 micromol/L (P = 0.02), no rejection episode before mCsA initiation (P = 0.005), and glomerulopathy as the primary renal disease (P = 0.001). CONCLUSION: Numerous kidney transplant recipients with a low immunological risk and good and stable renal function may benefit from discontinuation of prednisone and azathioprine in order to reduce the complications related to these drugs. This therapeutic approach had no adverse impact on the overall long-term graft survival for "low risk" and successful patients.

Adult↗
PubMed2000

Validation of a blind transpyloric feeding tube placement technique in pediatric intensive care: rapid, simple, and highly successful.

OBJECTIVE: Nasogastric feeding in intensive care is poorly tolerated as a result of gastroparesis. Transpyloric (TP) feeding has been limited by difficulty in tube placement. This study was to independently validate the success rate of a previously published bedside TP feeding tube (FT) placement technique. DESIGN: Prospective interventional study. SETTING: Tertiary pediatric intensive care unit (PICU) in a university hospital. PATIENTS: Children whose intensivist requested TP feeding, and who were without known fundoplication, pharyngeal trauma, or gastric ulceration. INTERVENTIONS: After informed consent, an unweighted polyurethane feeding tube with a flexible wire stylet was inserted using a standard technique with metoclopramide, right lateral position, and air insufflation during advancement until <2 mL air could be aspirated after insufflation of 5-10 mL air. The tubes were inserted by one of the authors, whose training was only to observe one insertion, then perform one insertion with supervision. MEASUREMENTS AND MAIN RESULTS: Patient demographics, procedural data, and success rate based on radiography were prospectively recorded. There were 71 insertions on 38 patients from February 1999 to October 1999. Patients were aged 56 +/- 69.8 months, weighed 17.8 +/- 18 kg, 69% were ventilated, and 56% received procedural sedation. Success rate for TP-FT placement was 63/71 insertions (88.7%) in an average of 7.43 +/- 6.85 mins (median, 5 mins; range, <1-45 mins); of 38 patients, 36 had a successful TP- FT (95%). Insertion was well tolerated. Of the successful TP-FTs, on day 1 (n = 63) the FT was in distal duodenum or jejunum in 51% and by days 3-5 (n = 51), this increased to 75%. CONCLUSIONS: Bedside placement of a TP-FT with this technique is simple, rapid, well tolerated, and highly successful with little training. Immediate radiograph to confirm TP placement may not always be necessary. In our experience, this technique has obviated the need to search for another method to achieve a transpyloric feeding tube.

Journal Article↗
PubMed2004

Intrapartum cesarean delivery after successful external cephalic version: a meta-analysis.

OBJECTIVE: We sought to estimate whether the risk of intrapartum cesarean delivery is higher in pregnancies after successful external cephalic version. DATA SOURCES: We searched the MEDLINE, PubMed, EMBASE, and Cochrane Library databases to identify relevant studies. Abstracts of the American College of Obstetricians and Gynecologists Annual Clinical Meeting and the Society for Maternal-Fetal Medicine Annual Meeting were searched by hand. STUDY SELECTION: Studies published between 1980 and 2002 that provided data allowing us to estimate the cesarean rate in both pregnancies after successful version and spontaneous cephalic-presenting pregnancies were selected. TABULATION, INTEGRATION, AND RESULTS: Relative risks (RRs) and 95% confidence intervals (CIs) between the 2 compared groups were calculated. We used a meta-analysis to assess the heterogeneity of the studies and to combine the results from the included studies. Six eligible studies were identified. The cesarean rate was 27.6% in pregnancies after successful version and 12.5% in cephalic-presenting pregnancies. The combined RR and 95% CI was 2.04 (1.43-2.91). The increased cesarean rate in pregnancies after successful version was accounted for primarily by a higher incidence of emergency cesarean delivery for dystocia and fetal distress; the RR (95% CI) for these 2 events was 2.19 (1.38-3.48) and 2.10 (1.18-3.75), respectively. CONCLUSION: The intrapartum cesarean delivery rate after successful version is 2 times that in pregnancies where there is spontaneous cephalic presentation. Pregnancies after successful version should not be considered the same as a normal pregnancy.

Cesarean Section↗
PubMed2006

Definition of successful defibrillation.

OBJECTIVES: The definition of defibrillation shock "success" endorsed by the International Liaison Committee on Resuscitation since the publication of Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiac Care has been removal of ventricular fibrillation at 5 secs after shock delivery. Although this success criterion provides a direct assessment of the primary task of a shock, it may not be the only clinically useful measure of shock outcome. We evaluated a different defibrillation success criterion to determine whether it could provide additional insight into the relative performance of different defibrillation shocks. DESIGN: A randomized study comparing monophasic and biphasic waveform shocks is reported with return of organized rhythm as the primary outcome measure of defibrillation success. PATIENTS: A total of 120 patients with out-of-hospital ventricular fibrillation as the first recorded rhythm were treated with defibrillation with automated external defibrillators. MEASUREMENTS AND MAIN RESULTS: Return of organized rhythm (two QRS complexes, <5 secs apart, <60 secs after defibrillation) was achieved in 31 monophasic shock (45%) and 35 biphasic shock (69%) patients (relative risk, 1.53, 95% confidence interval, 1.11-2.10). Logistic regression analysis revealed that shock waveform was the strongest independent predictor of return of organized rhythm (odds ratio, 4.0; 95% confidence interval, 1.67-10.0). Defibrillation success with the conventional International Liaison Committee on Resuscitation criterion was very high (91% and 98%, respectively) and not significantly different between groups. CONCLUSIONS: Return of organized rhythm proved to be a more sensitive measure of relative defibrillation shock performance than the conventional shock success criterion. Inclusion of return of organized rhythm as an end point in future clinical research could help discern more subtle defibrillation shock effects and contribute to further optimization of defibrillation technology.

Adult↗
PubMed2006

Successful mental health aging: results from a longitudinal study of older Australian men.

OBJECTIVE: The authors investigated the associations of medical and lifestyle factors with the mental health of men in their 80s. METHODS: This was a prospective study of a community-representative cohort of older men. Successful mental health aging was defined as reaching age 80 years with Mini-Mental State Examination score (MMSE) of 24 or more and Geriatric Depression Scale-15 items (GDS-15) score of 5 or less. RESULTS: Of 601 men followed for 4.8 years, 76.0% enjoyed successful mental health aging. Successful mental health aging was inversely associated with age (hazard ratio [HR] = 0.87; 95% confidence interval [CI]: 0.81-0.94), non-English-speaking background (HR = 0.42; 95% CI: 0.21-0.85), and the consumption of full-cream milk (HR = 0.63; 95% CI: 0.45-0.89), and directly associated with high school or university education (HR = 1.92; 95% CI: 1.34-2.75) and vigorous (HR = 1.89; 95% CI: 1.17-3.05) and nonvigorous physical activity (HR = 1.50; 95% CI: 1.05-2.14). Marital status, smoking and alcohol use, weekly consumption of meat or fish, and a medical history of hypercholesterolemia, hypertension, diabetes, myocardial infarction, and stroke were not associated with mental health outcomes in men aged 80 years or over. CONCLUSION: Three in four men who reach age 80 years undergo successful mental health aging. Factors associated with successful mental health aging include education and lifestyle behaviors such as physical activity. Lifestyle modification by means of increasing physical activity and reducing saturated fat intake may prove to be a safe, inexpensive, and readily available strategy to help maximize the successful mental health aging of the population.

Affect↗
PubMed2006

Spontaneous breathing trial predicts successful extubation in infants and children.

OBJECTIVE: To assess the value of a spontaneous breathing trial (SBT) using a flow-inflating bag in predicting extubation success. Secondary goals were to evaluate the positive and negative predictive accuracy of a 15-min SBT. DESIGN: Prospective, blinded, clinical study. SETTING: Pediatric intensive care unit (ICU) of a university hospital PATIENTS: Infants and children intubated for >or=24 hrs. INTERVENTIONS: Patients who met defined criteria for extubation underwent a 15-min SBT connected to a flow-inflating bag set to provide 5 cm H2O continuous positive airway pressure. MEASUREMENTS AND MAIN RESULTS: Seventy patients underwent the SBT. Respiratory rate, heart rate, blood pressure, and pulse oxygen saturations were recorded at baseline and at 5 and 15 mins into the SBT. The ICU physicians were blinded to the results of the SBT, and all patients were extubated at the end of the trial. Patients were observed for the next 24 hrs, and the need for noninvasive ventilation or reintubation (i.e., extubation failure) was recorded.Sixty-four patients (91%) passed the SBT with a subsequent extubation failure rate of 7.8% (only 1.6% required reintubation). Six of the 70 (9%) patients enrolled failed the trial, but half were extubated successfully. Successful completion of the SBT has a 95% sensitivity for predicting successful extubation with a positive predictive value of 92% and an odds ratio of 12 (95% confidence interval, 1.3, 53.7). The specificity of the SBT was 37% with a negative predictive value of 50%. Logistic regression analysis revealed a significant association between passing the SBT and extubation success (p = .017). CONCLUSIONS: A 15-min flow-inflating bag SBT represents a practical, reliable bedside test that has 95% sensitivity for predicting extubation success in pediatric ICU patients. A trial failure is associated with but does not accurately predict extubation failure.

Adolescent↗
PubMed1995

Sexual conflict: males with highest mating success convey the lowest fertilization benefits to females.

In natural populations of a coral reef fish (the bluehead wrasse, Thalassoma bifasciatum), males with the highest daily mating success produce the fewest sperm per mating, and this is reflected in significantly lower fertilization rates. The average amount released by males in pair-mating was 3.3 x 10(6) spermatozoa, resulting in a fertilization rate of 96%. Sperm released per spawn declined with increasing mating success, so that females mating with the most successful males had less than 93% of their eggs fertilized. It is unlikely that high mating-success males are physiologically incapable of increasing sperm production, because younger males with different mating strategies have absolutely larger testes and higher daily sperm output. Feeding experiments suggest that high-success males are diverting energy from gamete production to other fitness-enhancing activities such as mate guarding. Females incur the cost of low sperm release by having fewer of their eggs fertilized. There are no obvious compensatory benefits to females from mating with high-success males.

Animals↗
PubMed1999

Early determinants of lifetime reproductive success differ between the sexes in red deer.

In polygynous, sexually dimorphic species, sexual selection should be stronger in males than in females. Although this prediction extends to the effects of early development on fitness, few studies have documented early determinants of lifetime reproductive success in a natural mammal population. In this paper, we describe factors affecting the reproductive success of male and female red deer (Cervus elaphus) on the island of Rum, Scotland. Birthweight was a significant determinant of total lifetime reproductive success in males, with heavier-born males being more successful than lighter ones. In contrast, birthweight did not affect female reproductive success. High population density and cold spring temperatures in the year of birth decreased several components of fitness in females, but did not affect the breeding success of males. The results confirm the prediction that selection on a sexually dimorphic trait should be greater in males than in females, and explain the differential maternal expenditure between sons and daughters observed in red deer. Differences between the sexes in the effects of environmental and phenotypic variation on fitness may generate differences in the amount of heritable genetic variation underlying traits such as birthweight.

Adaptation, Physiological↗
PubMed2003

The effect of foraging parameters on the probability that a dive is successful.

In this paper, we investigate the foraging decisions of an animal that dives to obtain its food. It might seem reasonable to use the probability that the diver is successful in any dive as an indicator of habitat quality. We use a dynamic model of optimal prey choice to show that this interpretation of diving success is not generally valid. In particular, we show that diving success is not directly proportional to the overall rate of gain that can be achieved in an environment. Furthermore, some environmental factors can have a non-monotonic effect on the probability of success. For example, as the travel time to the foraging area increases, the probability of success may first increase and then decrease. We point out that the same conclusions are likely to apply in the context of mate choice, i.e. the probability of getting a mate may not be an indicator of the quality of the environment in terms of reproductive success.

Animals↗
PubMed1994

Integration of absolute ventricular fibrillation voltage correlates with successful defibrillation.

Previous work has suggested that at higher absolute ventricular fibrillation voltages (AVFV), the heart is more amenable to defibrillation. This study investigated in a canine model whether voltage integration of the AVFV is associated with the defibrillation success rate. The moving-average filter was used to process the ventricular fibrillation (VF) waveform recorded from Lead II of the electrocardiogram (ECG). In seven animals, defibrillation trials were analyzed using a dc shock (DCS) successful approximately 50% of the time when delivered randomly. For each of a total of 84 DCS (40% successes, 60% failures), the fibrillation waveform just prior to DCS was analyzed. The integration of the AVFV waveform was performed over various sample sizes including 1, 4, 8, 16, 64, and 128 ms, as well as the time equal to the mean VF cycle length. The results suggest that dc shocks delivered at instants of higher values of integrated AVFV over the various window sizes are associated with successful defibrillation. Window sizes less than 16 ms appeared to offer the best discrimination. The integration of AVFV over the entire VF cycle length was significantly higher for successful rather than unsuccessful DCS. This interesting observation is consistent with the clinical observation that "coarse" VF (high AVFV) is easier to defibrillate than "fine" VF (low AVFV). The use of voltage integration of AVFV may have potential implications in the improvement of defibrillation success in implantable devices.

Analysis of Variance↗
PubMed2001

Genetic consequences of polygyny and social structure in an Indian fruit bat, Cynopterus sphinx. II. Variance in male mating success and effective population size.

Variance in reproductive success is a primary determinant of genetically effective population size (Ne), and thus has important implications for the role of genetic drift in the evolutionary dynamics of animal taxa characterized by polygynous mating systems. Here we report the results of a study designed to test the hypothesis that polygynous mating results in significantly reduced Ne in an age-structured population. This hypothesis was tested in a natural population of a harem-forming fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae), in western India. The influence of the mating system on the ratio of variance Ne to adult census number (N) was assessed using a mathematical model designed for age-structured populations that incorporated demographic and genetic data. Male mating success was assessed by means of direct and indirect paternity analysis using 10-locus microsatellite genotypes of adults and progeny from two consecutive breeding periods (n = 431 individually marked bats). Combined results from both analyses were used to infer the effective number of male parents in each breeding period. The relative proportion of successfully reproducing males and the size distribution of paternal sibships comprising each offspring cohort revealed an extremely high within-season variance in male mating success (up to 9.2 times higher than Poisson expectation). The resultant estimate of Ne/N for the C. sphinx study population was 0.42. As a result of polygynous mating, the predicted rate of drift (1/2Ne per generation) was 17.6% higher than expected from a Poisson distribution of male mating success. However, the estimated Ne/N was well within the 0.25-0.75 range expected for age-structured populations under normal demographic conditions. The life-history schedule of C. sphinx is characterized by a disproportionately short sexual maturation period scaled to adult life span. Consequently, the influence of polygynous mating on Ne/N is mitigated by the extensive overlap of generations. In C. sphinx, turnover of breeding males between seasons ensures a broader sampling of the adult male gamete pool than expected from the variance in mating success within a single breeding period.

Animals↗
PubMed2002

Insecticide resistance enhances male reproductive success in a beetle.

Malathion-specific resistance in the red flour beetle, Tribolium castaneum, is widespread and stable in natural populations even in the absence of pesticide exposure. To understand this stability, both resistant and susceptible males were placed in competition for susceptible female fertilization. Females were then isolated and their progeny was tested for malathion susceptibility. Male reproductive success was estimated for populations originating from different geographic areas and for isogenic strains. In most cases, resistant males had a greater reproductive success rate than susceptibles. The results suggest that male reproductive success is not traded against the selection for malathion resistance, even resistant individuals are at an advantage for this fitness trait. This absence of fitness cost may be the result of postselection of (1) modifier gene which ameliorate the fitness of resistant individuals or (2) nondeleterious resistance gene. Resistant phenotype superiority could be due to increased male mating success, improved ability of resistant males in sperm competition, female mate choice, and/or cryptic female choice of resistance gene(s). The effect of male phenotypic frequency on male reproductive success was also examined. We observed that male fertilization success is frequency dependent and inversely related to their frequency. However, this "rare male" advantage did not counteract the superiority of the resistant males.

Animals↗
PubMed2007

Spring temperature, clutch initiation date and duck nest success: a test of the mismatch hypothesis.

1. Increases in average global temperature during the twentieth century have prompted calls for research on the effect of temperature variation on avian population dynamics. Particular attention has been paid to the hypothesis that increased temperatures may affect a species' ability to shift their breeding efforts to match the phenology of their prey, and thus result in reduced reproductive success (the 'mismatch hypothesis'). 2. We used data from a long-term study of breeding ducks to investigate how duck nest success varied with clutch initiation date, and to test whether spring temperature affected this relationship in a manner consistent with the mismatch hypothesis. We modelled five possible functional forms of how nest success might vary with clutch initiation date and spring temperature, and used an information-theoretic approach to determine which model best described the nesting outcomes of five dabbling duck species nesting in Saskatchewan, Canada. 3. Probability of nest success for the five species did not vary strongly with clutch initiation date, and we found evidence consistent with the mismatch hypothesis for one species, northern pintail Anas acuta, although weight of evidence was weak. 4. Overall nest success of all five species was positively associated with spring temperature. These results suggest that increasing spring temperature alone (within the range observed in this study) may not affect nest success in a manner that would result in lower populations of breeding ducks.

Animals↗