Clutch Failure Research Articles

Reconstructed and projected beach temperatures reveal where flatback turtles are most at risk from climate change

Nest temperature is the predominant driver of emergence success and primary sex ratios in sea turtles, with female offspring produced at higher temperatures due to temperature-dependent sex determination. However, emergence success and primary sex ratios are unfeasible to measure at scale, making methods to estimate these life-history traits from predicted sand temperatures highly desirable for long-term conservation planning in the context of climate change. To address this, we used a mechanistic microclimate model to predict hourly sand temperatures, over 32 nesting seasons since 1986, at 402 West Australian beaches supporting nesting by flatback turtles (Natator depressus). Predicted sand temperatures indicated that ∼70% of these beaches carried a 'very low' to 'intermediate' risk of subjecting embryos to thermal stress. By combining these temperature predictions with a physiological model, current and future emergence success and sex ratios were projected for ten different beaches spanning a range of thermal microclimates, under various climate change scenarios. Under recent climate conditions, emergence success averaged 76%, but declined to 63% and 37% with a 2°C and 4°C increase in air temperature, respectively. The sex ratios of hatchlings varied by location, but extremely skewed sex ratios were anticipated in a 4°C warming scenario. Our projections reveal that 'high risk' nesting beaches will regularly experience clutch failure as climate change progresses, while cooler beaches offer long-term nesting potential and require protection from additional anthropogenic impacts. These projections, covering an entire genetic stock, supply demographic data for assessing extinction risks and this method can be applied to sea turtle populations worldwide.

Influences of the Contact State between Friction Pairs on the Thermodynamic Characteristics of a Multi-Disc Clutch.

The relationship between clutch thermodynamic characteristics and contact states of friction components is explored numerically and experimentally. The clutch thermodynamic numerical model is developed with consideration of the contact state and oil film between friction pairs. The clutch bench test is conducted to verify the variation of the clutch thermodynamic characteristics from the uniform contact (UCS) to the intermittent contact (ICS). The results show that the oil film decreases gradually with increasing temperature; the lubrication state finally changes from hydrodynamic lubrication to dry friction, where the friction coefficient shows an increasing trend before a decrease. Thus, the friction torque in UCS gradually increases after the applied pressure stabilizes. When the contact state changes to ICS, the contact pressure increases suddenly and the oil film decreases rapidly in the local contact area, bringing about a sharp increase in friction torque; subsequently, the circumferential and radial temperature differences of friction components expand dramatically. However, if the contact zone is already in the dry friction state, friction torque declines directly, resulting in clutch failure. The conclusions can potentially be used for online monitoring and fault diagnosis of the clutch.

A Novel Method for Breakdown Prediction of Vehicle Clutch Using Multiple Linear Regression

The clutch is an important component of the transmission system in all aspects of car vehicle operation. The failure of a clutch in any vehicle has a direct impact on the vehicle's operation and, in some cases, on human safety as well. There are a variety of factors that might contribute to a clutch failure, including an overloaded vehicle, the use of the clutch in city traffic on a constant basis, and mistakes made during the gear shifting process. A high-priority demand is the ability to predict clutch failure, which is currently not achievable through vehicle diagnosis. This positional paper contributes to the use of multiple regression analysis technique to predict clutch life with the help of numerous vehicle parameters such as transmission oil temperature, vehicle speed, vehicle torque, vehicle engine speed, transmission oil level, accelerometer pedal position, parking brake status, and oil contamination. The consideration of many parameters adds to enhancing the accuracy of the forecast output by expanding the number of parameters considered. The proposed system's performance, which has an accuracy of 94 percent, is considered satisfactory. This technology can be used to notify drivers in Lehman language about projected consequences depending on the information provided by the system.

Analyse der durch Wasser verursachten Schädigungsmechanismen in nasslaufenden Fahrzeugkupplungen

To increase robustness of wet vehicle clutches extensive knowledge about damage mechanism within tribological stressed clutch friction contact are necessary, to derive suitable requirements for clutch development. Therefore, on the one hand comprehensive investigations on component-, unit- and vehicle test level are necessary which offer, amongst other information, learnings about the clutch component causing a possible clutch failure. On the other hand, component analyses have to be done, which make it possible detecting wear sensitive component elements of the component composition itself. Present analysis show results of damage mechanism caused by a non-permissible water impact and related molecular changes in clutch oil and tribological stressed functional steel plate surfaces. Analysis were done with electrospray-ionisation mass spectrometry and time-of-flight secondary ion mass spectrometry.

Why do sea turtle nests fail? Modeling clutch loss across the southeastern United States

AbstractUnderstanding the relative influence of environmental conditions and disturbance types on species' nest success is imperative to our estimation of current and future population trajectories of vulnerable species, especially ectotherms. The reproductive output of oviparous species is highly dependent on the location of a nest in terms of the environment experienced by incubating embryos and the risk of disturbance events. Climate change may present a particular danger to oviparous species because eggs cannot behaviorally regulate and avoid extreme temperatures. Hierarchical Bayesian models offer a powerful tool for utilizing available long‐term datasets to predict current and future species–environment relations in a manipulatable framework. We modeled the probability of depredation and inundation events occurring during incubation and how these disturbances, along with local climate, predict total clutch failure for loggerhead sea turtles (Caretta caretta) using a dataset of over 9000 nest inventories from five nesting areas that span the latitudinal extent of primary nesting locations in the United States. We found that nesting distance from the high waterline was important in determining the probability of inundation and depredation disturbance events, as well as clutch failure. Nests that experienced at least one inundation event were more likely to have no emergence than nests that experienced at least one depredation event, which may be the result of concerted efforts to control highly destructive nest predators in our study sites or the magnitude of inundation disturbances. Extreme high‐temperature events increased the probability of clutch failure, but the probability of clutch failure decreased with increasing average temperatures up to a critical threshold. The results of these models have clear implications for conservation management decisions on where to deploy predator deterrents and relocate nests, as well as the potential for predicting future changes in nest productivity across the broad nesting range of loggerhead sea turtles.

High clutch failure rate due to unpredictable rainfall for an ephemeral pool-breeding frog

Animals that reproduce in temporary aquatic systems expose their offspring to a heightened risk of desiccation, as they must race to complete development and escape before water levels recede. Adults must therefore synchronise reproduction with the changing availability of water, yet the conditions they experience to trigger such an event may not relate to those offspring face throughout development, potentially leading to clutch failure. The sandpaper frog (Lechriodus fletcheri) breeds in ephemeral pools that dry within days to weeks after rainfall has ceased. We examined whether spawning frequency and offspring survival differed across two consecutive breeding seasons based on (1) rainfall at the moment of oviposition and throughout offspring development, and (2) pool volume, given their combined effect on hydroperiod. Reproduction was triggered by rainfall, with more spawn laid during periods of greater rainfall and in larger pools. While pool size was a predictor of offspring survival, rainfall during oviposition was not. Rather, follow-up rain events were required to prevent pools drying prior to metamorphosis, with rainfall evenness during development the strongest predictor of reproductive success. High clutch failure rates recorded in both seasons suggest that adults do not have the capability to predict rainfall frequency post-oviposition. We thus conclude that unpredictable rainfall leading to premature desiccation of spawning sites is the primary source of pre-metamorphic mortality for this species. Understanding the influence of rainfall predictability on offspring survival could be critical in predicting the effects of altered hydroperiod regimes due to climate change for species that exploit temporary waters.

Multiple maternal risk-management adaptations in the loggerhead sea turtle (Caretta caretta) mitigate clutch failure caused by catastrophic storms and predators

Maternal risk-management, an extension of r/K selection, is an indispensable tool for understanding the natural selection pressures that shape the evolution of reproduction. Central to the construct of maternal risk-management is its definition of reproductive success as replacement fitness (w = 2), the survival of one breeding daughter to replace the female and one outbreeding son to replace her mate. Here, I apply maternal risk-management as a theoretical framework to explain multiple reproductive adaptations by loggerhead sea turtles nesting on a barrier island off the southern coast of Florida, US, from 1988 to 2004. Extrapolated over a 30-year reproductive span, nesting females averaged 4000–4500 eggs. I show that, rather than “putting all their eggs in one basket,” females divided eggs into 40 clutches of variable size (50–165 eggs). To deposit clutches, females migrated to the barrier island 10–12 times at unpredictable intervals of 2–8 years. Each nesting season, females deposited 1–7 clutches over diversified time intervals at diversified locations on the beach. Despite devastating clutch losses caused by ten catastrophic hurricanes, hundreds of erratic thunderstorms and dozens of predation events during this study, 72% of clutches produced by nesting females on this barrier island were undisturbed—median hatching success for these clutches was an astonishing 92%. I conclude that diversified maternal investments over time and space by nesting females are reproductive adaptations that have successfully offset clutch losses, thus enabling populations of loggerhead females to meet or exceed their reproductive goal of replacement fitness.

Математична модель зчеплення автомобіля Volkswagen Polo Sedan як об’єкта діагностування

When designing a car, designers must find a compromise between the dynamism and economy of the car, on the one hand, and reliability and safety - on the other. The first problem is solved mainly by reducing the weight of the car by optimizing the design and reducing strength reserves, and the second - by increasing the strength and durability of structural elements. Reliability of units of cars is the maximum at work on steady modes that confirms experience of their operation. It is known that in the conditions of country routes on good roads reliability of cars is essentially higher, than at operation within the city. In cities, unstable modes of operation of car units are caused, first of all, by frequent stops and subsequent accelerations due to the presence of traffic lights, pedestrian crossings, railway crossings, traffic jams, steep ascents and descents on car routes, etc. All this necessitates frequent braking, shifting gears and moving. These circumstances lead to an increase in the dynamic load of the vehicle units and, as a consequence, to the intensification of the processes of wear of the friction pairs of the clutch discs, gears and cardan gears, and so on. All the factors that reduce the reliability of car units in urban conditions are particularly evident in the example of buses and taxis with a manual transmission. According to some data, the share of failures of mechanical transmission units of such cars is 19 ... 23% of all failures. During intensive operation of the car, various clutch malfunctions can occur. There are malfunctions of the actual clutch and malfunction of the clutch drive. Coupling defects occur not only due to intensive operation, but also due to violations of operating rules. Currently, clutch failures are mainly diagnosed by external signs. However, one external feature may correspond to several clutch failures. Thus, the process of determining the technical condition of the clutch of vehicles is an urgent scientific and technical task. A mathematical model of the clutch of the Volkswagen Polo Sedan as an object of diagnosis are presents in the article. A matrix for diagnosing the clutch of a Volkswagen Polo Sedan and a block diagram of its synthesis have been built.

On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine

In order to reduce unnecessary stops and expensive downtime originating from clutch failure of construction equipment machines; adequate real time sensor data measured on the machine in combination with feature extraction and classification methods may be utilized.This paper presents a framework with feature extraction methods and an anomaly detection module combined with Case-Based Reasoning (CBR) for on-board clutch slippage detection and diagnosis in heavy duty equipment. The feature extraction methods used are Moving Average Square Value Filtering (MASVF) and a measure of the fourth order statistical properties of the signals implemented as continuous queries over data streams. The anomaly detection module has two components, the Gaussian Mixture Model (GMM) and the Logistics Regression classifier. CBR is a learning approach that classifies faults by creating a new solution for a new fault case from the solution of the previous fault cases. Through use of a data stream management system and continuous queries (CQs), the anomaly detection module continuously waits for a clutch slippage event detected by the feature extraction methods, the query returns a set of features, which activates the anomaly detection module. The first component of the anomaly detection module trains a GMM to extracted features while the second component uses a Logistic Regression classifier for classifying normal and anomalous data. When an anomaly is detected, the Case-Based diagnosis module is activated for fault severity estimation.

Sensory pollutants alter bird phenology and fitness across a continent.

Expansion of anthropogenic noise and nightlighting across our planet1,2 is of increasing conservation concern3-6. Despite growing knowledge of physiological and behavioural responses to these stimuli from single-species and local-scale studies, whether these pollutants affect fitness is less clear, as is how and why species vary in their sensitivity to these anthropic stressors. Here we leverage a large citizen science dataset paired with high-resolution noise and light data from across the contiguous United States to assess how these stimuli affect reproductive success in 142 bird species. We find responses to both sensory pollutants linked to the functional traits and habitat affiliations of species. For example, overall nest success was negatively correlated with noise among birds in closed environments. Species-specific changes in reproductive timing and hatching success in response to noise exposure were explained by vocalization frequency, nesting location and diet. Additionally, increased light-gathering ability of species' eyes was associated with stronger advancements in reproductive timing in response to light exposure, potentially creating phenological mismatches7. Unexpectedly, better light-gathering ability was linked to reduced clutch failure and increased overall nest success in response to light exposure, raising important questions about how responses to sensory pollutants counteract or exacerbate responses to other aspects of global change, such as climate warming. These findings demonstrate that anthropogenic noise and light can substantially affect breeding bird phenology and fitness, and underscore the need to consider sensory pollutants alongside traditional dimensions of the environment that typically inform biodiversity conservation.

Thermal Analysis of Clutch Assembly Using Co-Simulation Approach

<div class="section abstract"><div class="htmlview paragraph">Automotive clutches are rotary components which transmits the torque from the engine to the transmission. During the engagement, due to the difference in speed of the shafts the friction lining initially slips until it makes a complete engagement. Enormous amount of heat is generated due to the slippage of the friction lining, leading to poor shift quality and clutch failure. Depending on the road & traffic conditions, and frequency of engagement and disengagement of the clutch, it generates transient heating and cooling cycles.</div><div class="htmlview paragraph">Hill fade test with maximum GVW conditions being the worst case scenario for the clutch. A test was conducted to understand the performance of the clutch, in which clutch burning was observed. The clutch lining got blackened and burning smell was perceived. The friction coefficient drops sharply to a point until it cannot transmit the torque required to encounter the slope. This further worsen clutch slippage and lead to more severe temperature rise. The major reason attributed to the burning was inefficient cooling and less thickness of the flywheel & pressure plate. To address this issue transient CFD simulation is performed. Co-simulation methodology is applied to study how the solid temperature influences the air temperature at different time interval of the cycle. The temperature & convective heat transfer co-efficient data exchange happens across the domains after a fixed time interval mentioned in simulation. The heat generated in the solid components are mapped to the air and cooling effect of the fresh air from the ventilation holes are mapped on the solid. To replicate the exact test scenario varying launch energy, convective heat transfer coefficient and rpm is applied on the frictional discs as compared to the conventional steady state simulation approach where constant heat is applied on the frictional disc neglecting the cyclic variation of heating and cooling.</div><div class="htmlview paragraph">A physical test on vehicle was conducted for hill fade condition by inserting the thermocouples in the clutch housing close to the friction lining to measure the air temperature. The measured air temperature shows good trend of correlation with the predicted temperature.</div></div>

Investigation on the thermodynamic characteristics of the deformed separate plate in a multi-disc clutch

This work is devoted to investigate the thermodynamic characteristics of the deformed separate plate in a multi-disc clutch. The thermodynamic model is proposed, and the contact ratio of mating surface is varied to imitate the deformed plate. Moreover, the experimental study is conducted on the clutch test bench; in order to induce the plate deformation more easily, the thermometric plate has experienced the circumferential elastic deformation before experiments. Before the elastic deformation of separate plate occurs, the surface temperature increases steadily and the friction torque increases slowly with the increase of coefficient of friction. When the temperature gradient in the circumferential direction reaches the critical value 2–3 °C, the elastic deformation is excited. In the process of elastic deformation, the temperature growth rate in the contact zone increases dramatically, and the friction torque rises steeply. As for the variation of friction torque after the elastic deformation, it can be divided into three categories: increase smoothly, stable and decrease gradually. Moreover, at this stage, the smaller the contact ratio is, the higher the temperature in the contact zone is, and the greater the friction torque is. Meanwhile, with the decrease of the radial length and circumferential angle in the contact zone, the radial and circumferential temperature differences of the plate expand dramatically. The conclusions can be used as a theoretical basis for evaluating the real-time status of friction components and diagnosing the clutch failure.

Woodland birds and rural towns: artificial clutch survival in fragmented Box-Ironbark forests

Woodland birds are declining throughout the agricultural landscapes of south-eastern Australia, but the specific mechanisms driving these declines remain unclear. Reproductive failure via clutch depredation could conceivably contribute to these declines. Although site-scale habitat may influence the risk of clutch failure, larger-scale influences, such as whether a landscape contains a rural town or not (‘landscape type’), may also play a role. This study monitored artificial open-cup nests deployed in three pairs of the two landscape types and: 1) indexed clutch survival and predator assemblage; and 2) determined if clutch survival was influenced by landscape type and/or local habitat characteristics. High levels of clutch depredation were observed in both landscape types and for all landscapes, with no evidence to suggest that landscape type or habitat characteristics influenced clutch survival or the time-to-first-predator visit. Predator assemblage also was consistent between landscape types. Generalist avian predators were the most common egg predators. Such egg predators may be ubiquitous throughout the fragmented Box-Ironbark woodlands of south-eastern Australia.

A Research of Windlass Clutch Failure Based on the Model of DMAIC

A Research of Windlass Clutch Failure Based on the Model of DMAIC

Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds.

BackgroundGeolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8–2.0 g total, representing 0.1–3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2–4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26–1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables.ResultsWe detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5–5.8 % of body mass than if tags were 0.3–2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important.ConclusionsNegative effects of geolocators occurred only for three of the smallest species in our dataset, but were substantial when present. Future studies could mitigate impacts of tags by reducing protruding parts and minimizing use of additional markers. Investigators could maximize recovery of tags by strategically deploying geolocators on males, previously marked individuals, and successful breeders, though targeting subsets of a population could bias the resulting migratory movement data in some species.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-016-0077-6) contains supplementary material, which is available to authorized users.

Effects of Supplementary Feeding on the Breeding Ecology of the Buff-Throated Partridge in a Tibetan Sacred Site, China.

Our goal was to document effects of year-round supplemental feeding on breeding ecology of the Buff-throated Partridge, Tetraophasis szechenyii, within a Tibetan sacred site. We evaluated effects of supplemental feeding used as religious/cultural practices which could potentially aid conservation of endangered phasianids. We compared fed breeding groups to neighboring nonfed groups. Fed groups initiated first clutches significantly earlier than nonfed groups. Earlier laying groups within fed and nonfed groups showed significantly lower hatching rates than later groups; however, fed groups showed significantly higher hatching rates than nonfed groups laying in the same period. Earlier laying increased opportunities to renest. All six fed groups with clutch failures renested compared to only one of five nonfed groups with clutch failures. Fed female breeders showed significantly greater investment in their young with larger clutches and larger eggs, which likely increased survivability of early hatchlings. We observed no predation on birds at feeding sites and recorded only four cases of predation on incubating females, which showed no detectable difference between fed and nonfed groups. Ground-nesting birds typically face high risks of predation. Ten of the 48 groups nested in trees, which occurs in few phasianid species. Tree nests showed significantly higher hatching rates compared to ground nests; however, we found no significant difference in tree nesting between fed and nonfed groups. This partridge is one of four gallinaceous species with cooperative breeding. Breeding groups with helpers had significantly greater reproductive success than single pairs, and fed female breeders with helpers laid bigger eggs than single pairs. Comparing annual reproductive output per group, fed groups not only produced significantly more independent young (≥150 days post-hatching), their young hatched significantly earlier, which likely have greater reproductive value over later hatched young of nonfed groups. Supplemental feeding year-round is likely what enabled the successes of the fed partridges.

Does it Pay to Care?: Exploring the Costs and Benefits of Parental Care in the Hibiscus Harlequin BugTectocoris diophthalmus(Heteroptera: Scutelleridae)

AbstractKnowledge of the selective pressures favouring parental care can inform our understanding of the evolutionary origins and transitions of sociality in insects. Here, we report upon investigations designed to estimate the costs and benefits of parental care in the egg‐guarding hibiscus harlequin bugTectocoris diophthalmus(Heteroptera:Scutelleridae). We found that the presence of a guarding female had no effect on hatching success under benign laboratory conditions. In the wild, however, guarding decreased the likelihood of total clutch failure, and produced a fourfold greater egg‐hatching rate relative to unguarded clutches. Females guarded against generalist invertebrate egg predators, including conspecific nymphs, but were ineffective against hymenopteran egg parasitoids. Females continued to feed during the guarding period and exhibited no signs of weight loss or increased mortality due to this behaviour. We did not observe the production of subsequent clutches in any experimental females; therefore, the lifetime fecundity costs of providing parental care inT. diophthalmusremain indeterminate. Overall, maternal egg guarding appears to function as a relatively low cost–low benefit strategy that increases hatching success by protecting against predation – but not parasitism.

The Analysis and Design of a New Type Wedge Surfaces of Sprag Overrunning Clutch

Sprag overrunning clutch is one of key components in the drive system. Its a meaningful work to design and manufacture high performance sprag clutch to meet the practical working situation. In order to design reliable and durable clutch with good dynamic characteristics, this paper put forward a new type wedge surfaces which is a combination of involute and eccentric arc. On the basis of analysis of a clutch structure, work principles and failure modes, the sprag ,key element of the clutch, was demonstrated the feasibility of involute in the use of wedge surface design by analyzing the characteristics of involute, and the main sprag parameters were designed and analysized. The design of the new wedge surface, increasing the strut angle and effective cam rise, increased carrying capacity, reducing the contact stress, and extending service life, which laid the foundation for the sprag overrunning clutch design improvements.

Research on Design Theory and Experimental Validation of Dry Friction Automotive Clutch Based on Failure Mechanism

As a key component of vehicle, automotive clutch remained high failure rate, meanwhile, with the development of engine and vehicle technology, functional characteristics of automotive clutch such as comfort, durability and reliability demanded much higher. Objective of the study is to establish the correspondence relationship between failures and design theory and experimental methods, reduce failure rate and improve product reliability. In order to create a system approach of problem-solving, we collected clutch failure information and classified according to clutch functional requirements and mechanical design principles. Then we used RCA (root cause analysis) and quality management tools to analyze the cause of failures, used QFD (quality function development) and DFMEA (design failure mode effects analysis) method to protocol the corresponding control measures to improve the existing design theory and experimental methods. The study also can be applied to more complex systems such as dry dual clutch module and dual-mass flywheel damper.

Effects on tree swallows exposed to dioxin‐like compounds associated with the Tittabawassee River and floodplain near Midland, Michigan, USA

Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs), in soils and sediments downstream of Midland, Michigan (USA) were greater than upstream sites and prompted a site-specific hazard assessment of tree swallows breeding in the associated floodplains. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated at study areas (SAs) along the Tittabawassee and Saginaw rivers downstream of Midland. The site-specific multiple lines of evidence approach to hazard assessment included endpoints for dietary- and tissue-based exposures, and population productivity measurements for tree swallows ([TS]; Tachycineta bicolor) measured during the 2005, 2006, and 2007 breeding seasons. Exposure to dioxin-like compounds in TS eggs were some of the greatest recorded and were similar among all upstream and downstream study sites. Conversely, concentrations in nestlings from SAs were significantly greater compared to reference areas (RAs). The pattern of relative concentrations of PCDD/DFs in eggs and nestlings at RAs was dominated by dioxin congeners, whereas at SAs it was dominated by furan congeners. No statistically significant differences were noted in exposure to PCDD/DFs or in population-level responses when compared among locations, and total clutch failures were rare. Hatching success and fledging success were weakly negatively correlated with concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in individual eggs and nestlings, respectively. On-site concentrations of TEQs in floodplain soils were some of the greatest ever reported in the environment, and several lines of evidence indicate potential population-level effects on TS overall reproductive productivity.