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Résumé :
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In the autumns of 2014 and 2015 unprecedented numbers of Eared Grebes (Podiceps nigricollis) crashed along the central and southern California coast. Their origin was Mono Lake, California, one of the species’ two main staging areas. We posit that efforts in 1994 to restore a falling lake to historic level conditions coincided with a prolonged period of rapid rise, weakened upwelling, and decline in the grebes’ principal prey, brine shrimp (Artemia monica). This led to the starvation migrations and loss of most of the juvenile grebe cohort of perhaps >300,000 birds in each year. Adults avoided the mortality because of their better ability to dive for immature alkali flies (Ephydra hians). Even though the Eared Grebe is by far the most abundant bird at Mono Lake, its role in the ecosystem and the lake’s importance to the continental population has been largely ignored. The starvation data, backed by several grebe and extensive limnological data, show that the extreme mortality rate in 2014–2015 can be traced to the negative effects of lake level rise. An adaptive management program that addresses the entire lake ecosystem is a prerequisite for future restoration efforts.
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