Unusual dispersion and mortality of Rockhopper penguins. An event related to adverse marine conditions?

Between February and May 2016, a large number of Southern Rockhopper Penguins (Eudyptes chrysocome) were found molting and in part subsequently dying, apparently from starvation, along the southernmost coasts of Argentina. In order to report on the extent of this unusual dispersion and mortality event, direct counts of live and dead penguins were conducted along several coastal sites of Santa Cruz and Tierra del Fuego Provinces. To determine if this event might be related to changes in oceanographic conditions, chlorophyll a concentrations (productivity) and sea surface temperatures of the Southwest Atlantic Ocean were obtained for February and March 2016; and then compared with the 2010-2015 averages of the corresponding month. At least 1039 molting Rockhopper penguins were reported along the surveyed shores and 50-89 % ended dying, depending on the site. The 2016 oceanographic data showed lower productivity and higher sea surface temperature around Islas Malvinas, supporting the hypothesis of a shortage of food late summer close to breeding and feeding grounds from these islands, which could explain the dispersion of these penguins towards the Patagonian shores, and which finally led to a massive starvation event. This mortality event is a reminder of one that occurred in 1986 which was suspected to be related to El Niño event. Coincidentally during 2015-2016 El Niño manifested itself with great intensity. This study highlights the severe effects that changes in oceanographic parameters prior to a critical period (molting) might have on the survival of this endangered (Vulnerable) penguin species.