Beak deformation in an Antarctic Cormorant Phalacrocorax [atriceps] bransfieldensis chick

Fil: Casaux, Ricardo Jorge. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad Nacional de la Patagonia; Argentin

Feeding habits of three seal species at the Danco Coast, Antarctica: A re-assessment

The analysis of prey overlap among Weddell, Antarctic fur and leopard seals was conducted using fecal samples collected at the Danco Coast, Antarctic Peninsula, in 1998 and 2000. The re-occurrence of prey species was moderate in samples collected in 1998, and low in 2000, and reflects resource partitioning among seal species. Prey species that mostly co-occurred in seals' diet were the Antarctic krill Euphausia superba, bivalves, and the myctophids Gymnoscopelus nicholsi and Electrona antarctica. A dietary similarity index of prey overlap has been calculated and demonstrates evident fluctuations in pairwise comparisons between the seal species. The highest and lowest values of prey overlap were observed between Antarctic fur seals and leopard seals, and between Weddell seals and leopard seals, respectively. Prey overlap between Antarctic fur seals and Weddell seals was moderate in both seasons.Fil: Casaux, Ricardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Bertolin, María Lila. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Carlini, A.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Selective foraging by non-native rainbow trout on invertebrates in Patagonian streams in Argentina

Background It is well known that fish predation alters ecosystem processes by top-down effects. Salmonids are described as aggressive, visually and size-selective predators. Thus, prey selection by the non-native rainbow trout was examined on a seasonal basis at two streams: Nant y Fall (NyF) and Cabeza de Vaca (CVA) at Patagonia, a region where this kind of information is lacking. Results The benthos density at NyF was higher than that at CVA, and at both streams, riffles supported higher macroinvertebrate densities than pools. The diet of trouts from both streams was dominated by aquatic macroinvertebrates, was diverse, and was varied seasonally. The individuals represented in the stomach contents were among the largest available at the streams. Diet diversity peaked during spring at NyF and during summer at CVA, whereas at both streams, the niche width peaked during spring. Prey selectivity varied seasonally. The selected preys included both aquatic (Gasteropoda, Crustacea, Plecoptera, Trichoptera, Ephemeroptera, Coleoptera, Diptera, and Odonata) and terrestrial organisms (adult dipterans, Oligochaeta, Araneae, Homoptera, Hymenoptera, Orthoptera, and Hemiptera). Some infaunal invertebrates like oligochaetes and some small Coleoptera and Diptera larvae (mainly Chironomidae) were not selected by trouts. Conclusions Despite of the overall dominance of trichopteran species, the composition of the diet of the rainbow trout varied seasonally. This fish positively selected both aquatic and terrestrial organisms. We observed that in both streams, trouts consumed the larger individuals available in those environments.Fil: Di Prinzio, Cecilia Yanina. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Departamento de Biología. Laboratorio de Investigaciones En Ecología y Sistemática Animal; ArgentinaFil: Omad, Guillermo Hugo. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Departamento de Biología. Laboratorio de Investigaciones En Ecología y Sistemática Animal; ArgentinaFil: Miserendino, Maria Laura. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Departamento de Biología. Laboratorio de Investigaciones En Ecología y Sistemática Animal; ArgentinaFil: Casaux, Ricardo Jorge. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Departamento de Biología. Laboratorio de Investigaciones En Ecología y Sistemática Animal; Argentin

Diet of Antarctic fur seals <i>Arctocephalus gazella</i> at the Danco Coast, Antarctic Peninsula

The diet of non-breeding male Antarctic fur seals, Arctocephalus gazella, was investigated at the Danco Coast, Antarctic Peninsula, by the analysis of 31 and 149 scats collected from January to March 1998 and 2000, respectively. Overall, fish and krill, followed by penguins and squids, were the most frequent prey and constituted the bulk of the diet. The importance of the remaining taxa represented in the samples (octopods, gastropods, bivalves, isopods, polychaetes and poriferans) was negligible. Among fish, channichthyids constituted the bulk of the diet, with Chionodraco rastrospinosus and Chaenodraco wilsoni, followed by the nototheniid, Pleuragramma antarcticum, being the main prey. The myctophid, Electrona antarctica, was the most frequent and numerous fish prey. The results are discussed and compared with those reported for the South Shetland Islands, the closest area for which similar information is available.Facultad de Ciencias Médica

Geographical variation in the diet of the Antarctic fur seal <i>Arctocephalus gazella</i>

The diet of non-breeding male Antarctic fur seals Arctocephalus gazella was investigated at different localities of the Antarctic Peninsula (Cierva Point and Hope Bay), South Shetland Islands (Deception Island and Potter Peninsula) and the South Orkney Islands (Laurie Island), by the analysis of 438 scats collected from January to March 2000. The composition of the diet was diverse, with both pelagic and benthic-demersal prey represented in the samples. Antarctic krill Euphausia superba was the most frequent and numerous prey at all the study sites except at Cierva Point, followed by fish, penguins and cephalopods. Antarctic krill also predominated by mass, followed by either fish or penguins. Fish were the second most important prey by mass at the Antarctic Peninsula whereas penguins were the second most important prey by mass at the South Shetland and South Orkney Islands. Among fish, Pleuragramma antarcticum was the most important species in the diet of the Antarctic fur seals at the Antarctic Peninsula whereas Gymnoscopelus nicholsi predominated at the South Shetland and South Orkney Islands. The results are compared with previous studies, and the possibility of implementing monitoring studies on the distribution/abundance of myctophids and P. antarcticum based on the analysis of the diet of the Antarctic fur seal is considered.Facultad de Ciencias Naturales y MuseoFacultad de Ciencias Médica

First record of White-rumped Sandpiper (Calidris fuscicollis) at Esperanza/Hope Bay, Antarctica

The White-rumped Sandpiper (Calidris fuscicollis) (Vieillot 1819) is one of the longest migrating birds that breeds in the high Arctic in Alaska and Canada and spends the post-breeding period in South America. This bird is a frequent vagrant visitor of Islas Georgias del Sur/South Georgia and the South Shetland islands. Here we provide the first record for the White-rumped Sandpiper at the Continental Antarctica. The individual was observed the 2 February 2019 at Esperanza/Hope Bay (63° 23′ 56″ S, 56° 59′ 06″ W), the north of the Antarctic Peninsula, in an ice-free rockery close to a melt-water-run-off area. At the moment of the observation, the temperature was above 0 °C and the wind calm. However, strong winds from the north-west and west directions were registered during the last week of January 2019 at Esperanza Station (peak 65 knots) and at the Drake Passage (peak 49 knots) which might explain the presence of the White-rumped Sandpiper individual at Hope Bay. Our report contributes to list the non-native species observed in Antarctica. One plausible explanation could be related to changes in migratory routes of flying birds.Facultad de Ciencias Naturales y Muse

Diet of Adélie penguins (<i>Pygoscelis adeliae</i>) at Stranger Point (25 de Mayo/King George Island, Antarctica) over a 13-year period (2003–2015)

Knowledge of the feeding ecology of a species at local level is fundamental to determine the relationship between the fluctuations in local marine resources and population dynamics of predators. In this study, we examined the diet of Adélie penguins (Pygoscelis adeliae) during the crèche stage at the Stranger Point colony, South Shetland Islands, Antarctica, over a 13-year period (2002/2003–2014/2015). Antarctic krill (Euphausia superba) was the dominant prey for Adélie penguins during the crèche period (contribution: 100% of occurrence and >99.7% by mass). The fish component in the diet represented a small proportion of the total prey (contribution: from 4 to 24% of occurrence but <0.15% by mass). A marked inter-annual variability in the mass of stomach contents, the krill size consumed and the proportion of juvenile krill was observed. Moreover, a possible recruitment event of krill was recorded. A negative relationship between the size of krill in the diet and breeding success was found, suggesting that population dynamics of krill also reflected changes in the local availability of this crustacean. This work is the first long-term study of dietary parameters of Adélie penguins for the Stranger Point colony.Facultad de Ciencias Naturales y Muse

Biología reproductiva y ecología alimentaria del Cormorán antártico Phalacrocorax bransfieldensis (Aves: phalacrocoracidae) en las Islas Shetland del Sur, Antártida

Facultad de Ciencias Naturales y Muse

Diving patterns in the Antarctic Shag

The diving patterns of the Antarctic Shag ( Phalacrocorax bransfieldensis ) were studied by direct observation on individuals foraging at Harmony Cove, Nelson Island, South Shetland Islands, during the 1995/96 and 1996/97 breeding seasons. The individuals observed foraged in shallow waters, mainly solitarily and presumably dived aerobically. The shags displayed relatively short diving bouts composed of few dives. During the 1995/96 breeding season, the duration of the dives decreased with the increase in the number of dives per bout and increased with the diving depth. These relationships were not statistically significant in 1996/97. In both seasons, the duration of the dives was positively related with both the surface resting time preceding and succeeding the dive, which may indicate that these birds display anticipatory or reactive dives probably according to the foraging conditions. Shags at the surface were seen swallowing fish longer than 15 cm; smaller fish as well as invertebrates may have been ingested underwater. The mean diving efficiencies of the bouts fall within the range reported for phalacrocoracids, but values of diving efficiency below unity were observed.Fil: Casaux, Ricardo Jorge. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Does prey availability influence the foraging effort and breeding success in the Antarctic Shag Phalacrocorax bransfieldensis?

Information on diet composition, foraging effort and breeding success of the Antarctic Shag (Phalacrocorax bransfieldensis) was obtained at three colonies on the Antarctic Peninsula, during the 1997/98 breeding season. Fish was the most important prey at each of the colonies sampled, followed by octopods and gastropods. Among colonies, there were marked differences in the size of the fish consumed, which was smaller at Py Point. This was mainly due to the larger number of specimens of the smallest fish prey species consumed there. Shags from Py Point performed longer foraging trips and spent more time per day foraging. Although at the beginning of the study the number of chicks per nest observed at the three colonies was similar, the number surviving to fledge at Py Point was markedly lower. The relative higher foraging effort and lower breeding success observed at Py Point might be related to the differences in the fish consumed between colonies. My results suggest that the decline in the inshore fish populations observed around the South Shetland Islands could be one of the reasons explaining the steady decrease in the number of breeding Antarctic Shags observed at colonies monitored in this archipelago.Fil: Casaux, Ricardo Jorge. Universidad Nacional de la Patagonia