About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Threequarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. Studies show that only a fraction of birds that die at sea typically wash ashore, and we estimate that total mortality approached 1 million birds. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016-2017) the mass mortality event. Die-offs and breeding failures occur sporadically in murres, but the magnitude, duration and spatial extent of this die-off, associated with multi-colony and multi-year reproductive failures, is unprecedented and astonishing. These events cooccurred with the most powerful marine heatwave on record that persisted through 2014-2016 and created an enormous volume of ocean water (the "Blob") from California to Alaska with temperatures that exceeded average by 2-3 standard deviations. Other studies PLOS ONE | https://doi.org/10.1371/journal.pone.0226087 January 15, 2020 1 / 32 OPEN ACCESS Citation: Piatt JF, Parrish JK, Renner HM, Schoen SK, Jones TT, Arimitsu ML, et al. (2020) Extreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016. PLoS ONE 15(1):indicate that this prolonged heatwave reduced phytoplankton biomass and restructured zooplankton communities in favor of lower-calorie species, while it simultaneously increased metabolically driven food demands of ectothermic forage fish. In response, forage fish quality and quantity diminished. Similarly, large ectothermic groundfish were thought to have increased their demand for forage fish, resulting in greater top-predator demands for diminished forage fish resources. We hypothesize that these bottom-up and top-down forces created an "ectothermic vise" on forage species leading to their system-wide scarcity and resulting in mass mortality of murres and many other fish, bird and mammal species in the region during 2014-2017.

populations était aussi très sensible aux variations unitaires ou proportionnelles du succès d'éclosion moyen et des taux de survie des canetons ou des juvéniles. Étant donné les faibles effectifs d'échantillons disponibles pour certains aspects-clé du cycle de vie du Petit Fuligule, nous recommandons que des travaux additionnels soient effectués sur les taux vitaux qui ont une influence majeure sur l'accroissement des populations et leur effectif (ex. taux de survie des adultes). Nos modèles de cycle de vie devraient être testés et mis à jour régulièrement afin de guider l'étude et la gestion des populations de Petit Fuligule dans un contexte adaptatif.

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Organisms that reproduce in temperate regions have limited time to produce offspring successfully, and this constraint is expected to be more pronounced in areas with short growing seasons. Information concerning how reproductive ecology of endotherms might be influenced by growing season length (GSL) is rare, and species that breed over a broad geographic range provide an opportunity to study the effects of time constraints on reproductive strategies. We analyzed data from a temperate-breeding bird, the lesser scaup Aythya affinis; hereafter scaup, collected at eight sites across a broad gradient of GSL to evaluate three hypotheses related to reproductive compensation in response to varying time constraints. Clutch initiation date in scaup was unaffected by GSL and was unrelated to latitude; spring thaw dates had a marginal impact on timing of breeding. Clutch size declined during the nesting season, as is reported frequently in bird species, but was also unaffected by GSL. Scaup do not appear to compensate for shorter growing seasons by more rapidly reducing clutch size. This study demonstrates that this species is remarkably consistent in terms of timing of breeding and clutch size, regardless of growing season characteristics. Such inflexibility could make this species particularly sensitive to environmental changes that affect resource availabilities.