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Many shorebird species undertake long-distance migrations punctuated by brief stays at food-rich, estuarine stopover locations. Understanding use of these food resources helps guide conservation and responsible development decisions. We determined the extent and degree to which Western Sandpiper (Calidris mauri) utilized biofilm as a food resource across a large and variable stopover location during northward (spring) migration. We investigated the spatial heterogeneity in diet composition, to determine whether shorebirds were consistently feeding on biofilm or whether diet varied between naturally and anthropogenically delineated sites. We used stable isotope analysis to estimate that biofilm conservatively comprised 22% to 53% of Western Sandpiper droppings across all sampling sites and that prey composition differed significantly between areas within the stopover location. Widespread biofilm consumption demonstrates the importance of biofilm as a dietary component. Variable diet composition suggests that habitat heterogeneity may be an important component of high quality stopover locations in the context of \"state-dependant trade-offs\" of Western Sandpiper population sub-groups. Future management decisions must consider and address potential impacts on the biofilm community throughout a stopover location, as single site studies of diet composition may not be adequate to develop effective management strategies for entire stopover sites.

The Iberia–Newfoundland continental margin is one of the most-studied conjugate margins in the world. However, many unknowns remain regarding the nature of rifting preceding its break-up. We analyse a large dataset of tectonic subsidence curves, created from publicly available well data, to show spatial and temporal trends of rifting in the proximal domains of the margin. We develop a novel methodology of bulk averaging tectonic subsidence curves that can be applied on any conjugate margin with a similar spread of well data. The method does not rely on the existence of conjugate, deep seismic profiles and, specifically, attempts to forego the risk of quantitative bias derived from localized anomalies and uncertain stratigraphic dating and correlation. Results for the Iberia–Newfoundland margin show that active rift-driven tectonic subsidence occurred in the Central segment of the conjugate margin from c. 227 Ma (early Norian) to c. 152.1 Ma (early Tithonian), in the southern segment from c. 208.5 Ma (early Rhaetian) to c. 152.1 Ma (early Tithonian) and in the northern segment from c. 201.3 Ma (early Hettangian) to c. 132.9 Ma (early Hauterivian). This indicates that rifting in the stretching phase of the proximal domain of the Iberia–Newfoundland margin does not mirror hyperextended domain rifting trends (south to north) that ultimately led to break-up. The insights into broad-scale three-dimensional spatial and temporal trends, produced using the novel methodology presented in this paper, provide added value for interpretation of the development of passive margins, and new constraints for modelling of the formation of conjugate margins.

Chronic kidney disease (CKD) in childhood is associated with neurocognitive deficits. Affected children show worse performance on tests of intelligence than their unaffected siblings and skew toward the lower end of the normal range. Here we further assessed this association in 340 pediatric patients (ages 6–21) with mild–moderate CKD in the Chronic Kidney Disease in Childhood cohort from 48 pediatric centers in North America. Participants underwent a battery of age-appropriate tests including Conners’ Continuous Performance Test-II (CPT-II), Delis–Kaplan Executive Function System Tower task, and the Digit Span Backward task from the age-appropriate Wechsler Intelligence Scale. Test performance was compared across the range of estimated glomerular filtration rate and duration of CKD with relevant covariates including maternal education, household income, IQ, blood pressure, and preterm birth. Among the 340 patients, 35% had poor performance (below the mean by 1.5 or more standard deviations) on at least one test of executive function. By univariate nonparametric comparison and multiple logistic regression, longer duration of CKD was associated with increased odds ratio for poor performance on the CPT-II Errors of Commission, a test of attention regulation and inhibitory control. Thus, in a population with mild-to-moderate CKD, the duration of disease rather than estimated glomerular filtration rate was associated with impaired attention regulation and inhibitory control.

We report a fight involving multiple American Crows attacking and nearly killing a single crow. Our observation suggests that the social structure of crow societies is maintained at both an individual and group level.

The Fraser River Delta in British Columbia, Canada, is a globally significant stopover site for shorebirds, but the population status and trends of many species that use the site remain uncertain. We describe an ongoing program to monitor population trends of the two most abundant species, Western Sandpipers (Calidris mauri) and Dunlins (Calidris alpina), during northward migration. Counts of these species were conducted at a mudflat where large flocks assembled at mid-tide from 15 April to 15 May, 1991—2013, and we estimated species-specific counts as the product of daily total flock counts and species proportions obtained during supplementary sampling. The median peak count of both species combined was 177,000 birds, and occurred between 24 April and 3 May. Ratios (proportions) of the two species followed a predictable pattern during the migration period, with a low proportion of Western Sandpipers (3%–20%) in flocks before 20 April, followed by a rapid increase to 80%–100% between 25 April and 10 May and a variable decrease to 30%–80% by 15 May. Mean counts of Western Sandpipers showed no significant trend over the study period. Mean counts of Dunlins showed a non-linear trend, decreasing until 2001 and then increasing to 2013. Bias and random error in field counts were quantified by comparing field counts to counts made from photographs taken during surveys, and analysis revealed that field counts had a downward, but predictable, bias, accounting for >90% of birds present, with a stochastic error rate of 28.0%. Uncertainty in total population estimates was high after accounting for the effect of length of stay and sampling error. Population estimates suggested that 600,000 Western Sandpipers and 200,000 Dunlins typically passed through the site during northward migration. Our estimates indicate the usefulness of daily counts at major stopover sites during northward migration as an effective tool for monitoring shorebird populations, and underscore the need for conserving such sites. La desembocadura del rio Fraser en British Columbia, Canada, es una localidad de importancia global como sitio de parada para aves playeras, sin embargo se desconoce el estatus poblacional y las tendencias de muchas especies que usan este sitio. Describimos un programa en desarrollo para monitorear las tendencias de dos especies abundantes, Calidris mauri y Calidris alpina, durante la migración hacia el norte. Realizamos conteos de estas especies en una llanura de marea donde se ensamblan bandadas grandes durante media marea desde el 15 de Abril hasta el 15 de Mayo de 1991–2013. Estimamos conteos especie-específicos como el producto del conteo total de las bandadas y las proporciones de especies obtenidas durante muestreo suplementario. El pico de la mediana para el conteo de las dos especies combinadas fue de 177,000 aves, el cual ocurrió entre el 24 de abril y 3 de mayo. Las proporciones de las dos especies siguieron un patrón predecible durante el periodo de migración, con una proporción baja de Calidris mauri (3%–20%) en las bandadas antes del 20 de Abril, seguido por un incremento rápido hasta llegar al 80%–100% entre el 25 de Abril y el 10 de Mayo y finalmente una reducción variable hasta llegar al 30%–80% aproximadamente el 15 de mayo. El promedio de los conteos de Calidris mauri no mostro una tendencia significativa durante el periodo de estudio. El promedio de los conteos de Calidris alpina mostro una tendencia no linear, con una reducción hasta el 2001 y luego un incremento en la hasta el 2013. Cuantificamos el sesgo y el error aleatorio de los conteos en campo comparándolos con conteos realizados utilizando fotografías tomadas durante los monitoreos. El análisis revelo que los conteos en campo tienden a subestimar predeciblemente las poblaciones teniendo en cuenta >90% de las aves presentes con una tasa de error estocástico del 28.0%. La incertidumbre en los estimativos de la población total fue alta después de tener en cuenta el efecto del tiempo de estadía y el error de muestreo. Las estimaciones de la población sugieren que 600,000 Calidris mauri y 200,000 Calidris alpina pasaron normalmente a través del sitio durante la migración hacia el norte. Nuestros estimados indican la utilidad de los conteos diarios en los principales sitios de parada durante la migración hacia el norte como una herramienta eficaz para el monitoreo de las poblaciones de aves playeras y resaltan la necesidad de conservar estos sitios.

The presence of top predators can affect prey behaviour, morphology and life history, and thereby can produce indirect population consequences greater and further reaching than direct depredation would have alone. Raptor species in the Americas are recovering since restrictions on the use of dichlorodiphenyltrichloroethane (DDT) and the implementation of conservation measures, in effect constituting a hemisphere-wide predator-reintroduction experiment, and profound effects on populations of their prey are to be expected. Here, we document changes in the behaviour of western sandpipers (Calidris mauri) at migratory stopover sites over two decades. Since 1985, migratory body mass and stopover durations of western sandpipers have fallen steadily at some stopovers in the Strait of Georgia, British Columbia. Comparisons between years, sites and seasons strongly implicate increasing danger from the recovery of peregrine falcons (Falco peregrinus) as a causal factor. A decade-long ongoing steep decline in sandpiper numbers censused on our study site is explained entirely by the shortening stopover duration, rather than fewer individuals using the site. Such behavioural changes are probably general among migratory shorebird species, and may be contributing to the widespread census declines reported in North America.

It is now generally accepted that central nervous system treatments for childhood cancer can result in significant cognitive impairment, most commonly in the areas of attention/concentration. We review the literature on attentional and neurocognitive deficits in this population, and also efforts to remediate attentional deficits in other brain injured populations. It was our goal to develop an innovative, psychologically based outpatient rehabilitation program that would improve dysfunctional attentional processes and associated neuropsychological deficits. The characteristics of this program and a pilot study of its effectiveness are described. Participants were 31 off-therapy cancer survivors with documented attention deficits. Twenty-one completed the cognitive remediation program (CRP) and 10 served as comparisons. All participants completed a test of vigilance attention, 2 tests with an attentional component, and an arithmetic academic achievement measure. When the scores of the 2 groups were compared, the CRP group exhibited statistically significant improvement on all attentional measures. In contrast, the comparison group did not manifest any significant changes. Neither group demonstrated statistically significant changes on the arithmetic achievement test. We believe that the CRP has potential for improving attention/concentration, but generalization to academic achievement remains unproven. Phase 3 clinical trials and the documentation of long-term treatment gains are needed. Furthermore, it will be necessary to demonstrate the ecological validity of the CRP. With these caveats, this therapeutic approach may be helpful in other populations of cognitively impaired children and young adults, such as patients who have suffered traumatic brain injury. (JINS, 2002, 8, 115–124.)

We examine the potential selective importance of predation danger on the evolution of migration strategies of arctic-breeding calidrid sandpipers. Adult calidrids truncate parental care for reasons not obviously related to levels of food abundance on the breeding areas or at migratory stopover sites, suggesting that a different trade-off occurs between providing additional care and adult survivorship. The southward migrations of adult western sandpipers precede those of migratory peregrine falcons by almost a month. By moving early and quickly, adults remain ahead of migrant falcons all the way to their non-breeding areas, where they rapidly moult flight feathers. They complete the moult just as falcons arrive in late September-October. By migrating early, they avoid exposure to falcons when they are unusually vulnerable, due to the requirements for fuelling migratory flight and of wing feather moult. Juvenile western sandpipers migrate south just as falcon numbers start to increase, but do not moult flight feathers in their first winter. Pacific dunlin use an alternative strategy of remaining and moulting in Alaska after falcons depart, and migrating to their overwintering sites after migrants have passed. East of the Rocky Mountains, the southbound migration of falcons begins 4-6 weeks later. Southbound semipalmated sandpipers make extended migratory stopovers, but their lengths of stay shorten prior to falcon migration to the sites in September. Predation danger also may affect the evolution of migration routes. Southbound western sandpipers fly directly from Alaska to southern British Columbia, in contrast to the multi-stage journey northward along the Alaska panhandle. We estimate that a direct flight would be more economical on northward migration, but may be avoided because it would expose sandpipers to higher mass-dependent predation danger from migratory falcons, which travel north with sandpipers. By contrast, few raptors are present in Alaska during preparation for the southward flight. A temporal and spatial window of safety may also permit semipalmated sandpipers to become extremely vulnerable while preparing for trans-Atlantic southward flights. Danger management may account for the these previously enigmatic features of calidrid migration strategies, and aspects of those of other birds.