We describe the development and initial application of a semiautomated parentage testing system in the Seychelles warbler (Acrocephalus sechellensis). This system used fluorescently labelled primers for 14 polymorphic microsatellite loci in two multiplex loading groups to genotype efficiently over 96% of the warbler population on Cousin island. When used in conjunction with the program cervus, this system provided sufficient power to assign maternity and paternity within the Seychelles warbler, despite the complications associated with its cooperative breeding system and a relatively low level of genetic variation. Parentage analyses showed that subordinate ‘helper’ females as well as the dominant ‘primary’ females laid eggs in communal nests, indicating that the Seychelles warbler has an intermediate level of female reproductive skew, in between the alternative extremes of helper‐at‐the‐nest and joint nesting systems. Forty‐four per cent of helpers bred successfully, accounting for 15% of all offspring. Forty per cent of young resulted from extra‐group paternity.

The economic value of the European Centre for Medium-Range Weather Forecasts (ECMWF) operational ensemble prediction system (EPS) is assessed relative to the value of a perfect deterministic forecast. The EPS has substantial relative value throughout the medium range. Probability forecasts derived from the EPS are of greater benefit than a deterministic forecast produced by the same model. Indeed, for many users, the probability forecasts have more value than a shorter-range deterministic forecast. Based on the measures used here, the additional information in the EPS (reflecting the uncertainty in the initial conditions) provides a benefit to users equivalent to many years' development of the forecast model and assimilation system.The impact of ensemble size on forecast value is considered. The difference in performance between ensembles with 10 and with 50 members may appear relatively small, based on standard skill measures, yet the larger ensembles have substantial benefit to a range of users. Further increases in ensemble size may be. expected to provide additional value.

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Quantifying forecast uncertainty with an ensemble approach can improve the users' bottom line D uring the past decade, due to increased computer resources, the development of more realistic atmospheric models, and the recognition of the importance of atmospheric predictability in general, ensemble forecasting became a major component of Numerical Weather Prediction (NWP). NWP centers around the globe [European Centre for Medium-Range Weather Forecasts (ECMWF),

Four recent papers have investigated the effects of ensemble size on the Brier score (BS) and discrete ranked probability score (RPS) attained by ensemble-based probabilistic forecasts. The connections between these papers are described and their results are generalized. In particular, expressions, explanations and estimators for the expected effect of ensemble size on the RPS and continuous ranked probability score (CRPS) are obtained.