Juan Emilio Sala

Flexible foraging for finding fish: variable diving patterns in Magellanic penguins Spheniscus magellanicus from different colonies

AbstractSeabirds have to deal with environmental variability and are predicted to modulate foraging behavior to maximize fitness, with particularly strong selection pressure for optimal behavior during chick provisioning when energy demands are high. We reported data from 42 breeding birds equipped during the early chick-rearing period with depth recorders at four different colonies [Punta Norte (42°S), Bahía Bustamante (45°S), Puerto Deseado (47°S) and Puerto San Julián (49°S)] in patagonian Argentina. Although Magellanic penguins are purported to show little flexibility in foraging behavior, we discovered marked inter-colony differences in diving behavior. Even though the southern marine ecosystems, in general, and the area exploited by Magellanic penguins from the studied colonies, in particular, are usually characterized by their stability, we cannot entirely exclude that interannual differences may have also affected our results. The colonies located in the center of the breeding distribution, Bahía Bustamante and Puerto Deseado, showed the greatest diving and foraging effort with Bahía Bustamante penguins having the deepest and longest dives of all birds and requiring the longest post-dive recovery durations at the surface. Puerto Deseado had the birds with the highest values of diving effort parameters. Penguins from both colonies also had the highest descent and ascent rates during dives. We assume that the clear variation in diving behavior reflects the response of the birds to the varying prey types and availability around the different colonies, but note that, despite this, some colonies fare markedly better than others in breeding.ZusammenfassungFlexible Suche nach Fisch: unterschiedliche Tauchmuster von Magellan -PinguinenSpheniscus magellanicusaus verschiedenen Kolonien Seevögel müssen Umweltveränderungen bewältigen und können vermutlich ihre Nahrungssuche anpassen, um ihre Fitness zu maximieren, vor allem bei starkem Selektionsdruck für optimales Verhalten während der Jungenaufzucht, wenn der Energiebedarf besonders hoch ist. In vier verschiedenen Kolonien [Punta Norte (42°S), Bahía Bustamante (45°S), Puerto Deseado (47°S) and Puerto San Julián (49°S)] im argentinischen Teil Patagoniens wurden während der frühen Kükenaufzuchtsphase 42 Brutvögel mit Tiefenmessern ausgerüstet. Obwohl Magellan-Pinguine angeblich eine geringe Flexibilität im Nahrungssuchverhalten zeigen, konnten deutliche Unterschiede im Tauchverhalten zwischen den Kolonien festgestellt werden. Wenngleich die südlichen marinen Ökosysteme im Allgemeinen, und das von den untersuchten Magellan-Pinguinen genutzte Gebiet im Speziellen, normalerweise durch ihre Stabilität gekennzeichnet sind, kann nicht gänzlich ausgeschlossen werden, dass Unterschiede zwischen den Jahren die Ergebnisse beeinflusst haben könnten. Die Kolonien, die in der Mitte des Brutverbreitungsgebietes liegen, Bahía Bustamante und Puerto Deseado, zeigten den größten Aufwand für Tauchen und Nahrungssuche. Die Bahía Bustamante Pinguine tauchten von allen Vögeln am tiefsten und am längsten und benötigten die längsten Erholungsphasen an der Wasseroberfläche nach ihren Tauchgängen. Puerto Deseado Pinguine zeigten die höchsten Werte im Tauchaufwand. Vögel aus beiden Kolonien hatten die höchsten Ab- und Auftauchgeschwindigkeiten während der Tauchgänge. Wir nehmen an, dass die Unterschiede im Tauchverhalten die Antwort der Vögel auf variierende Beutetypen und deren Verfügbarkeit um die verschiedenen Kolonien reflektiert. Ungeachtet dessen ist aber darauf hinzuweisen, dass das Brutgeschäft in einigen Kolonien deutlich besser läuft als in anderen.

Post-mortem findings in southern right whales Eubalaena australis at Península Valdés, Argentina, 2003-2012.

Between 2003 and 2012, 605 southern right whales (SRW; Eubalaena australis) were found dead along the shores of Península Valdés (PV), Argentina. These deaths included alarmingly high annual losses between 2007 and 2012, a peak number of deaths (116) in 2012, and a significant number of deaths across years in calves-of-the-year (544 of 605 [89.9%]; average = 60.4 yr(-1)). Post-mortem examination and pathogen testing were performed on 212 whales; 208 (98.1%) were calves-of-the-year and 48.0% of these were newborns or neonates. A known or probable cause of death was established in only a small number (6.6%) of cases. These included ship strike in a juvenile and blunt trauma or lacerations (n = 5), pneumonia (n = 4), myocarditis (n = 2), meningitis (n = 1), or myocarditis and meningitis (n = 1) in calves. Ante-mortem gull parasitism was the most common gross finding. It was associated with systemic disease in a single 1-2 mo old calf. Immunohistochemical labeling for canine distemper virus, Toxoplasma gondii and Brucella spp., and PCR for cetacean morbillivirus (CeMV), influenza A, and apicomplexan protozoa were negative on formalin-fixed, paraffin-embedded lung and brain samples from a subset of whales; PCR for Brucella spp. was positive in a newborn/neonate with pneumonia. Skin samples from whales with gull parasitism were PCR negative for CeMV, poxvirus, and papillomavirus. This is the first long-term study to investigate and summarize notable post-mortem findings in the PV SRW population. Consistent, significant findings within or between years to explain the majority of deaths and those in high-mortality years remain to be identified.