Seabird Censuses at Antarctic and Subantartic Waters: results from 1987-1995

Un total de 182.810 aves marinas pertenecientes a 50 especies fueron censadas en diferentes localidades de Antártida y Océano Atlántico Sur en las temporadas de verano 1987 a 1995. Los censos fueron hechos a bordo de buques siguiendo la metodología recomendada por el S.C.A.R., realizando 9.281 observaciones de 10 minutos cada una. Fueron definidas seis subáreas antárticas y subantárticas. Las mayores abundancias fueron obtenidas en las sub áreas de las Islas Orcadas del Sur y Arco de Scotia e Islas Shetland del Sur. Las abundancias fueron comparadas con las distintas sub áreas y con factores ambientales tomados al momento del censo (temperatura del aire y cobertura de hielo). Se discute la influencia que estos factores ambientales ejercen en la distribución de las especies.A total number of 182,810 seabirds of 50 species was recorded at Antarctica and South Atlantic Ocean in consecutive summers from 1987 to 1995. 9,281 ten minute censuses were made onboard ships following S.C.A.R. methodology. Six Antarctic and Subantarctic sub-areas were considered for study. The largest abundance was recorded at South Orkney Is. and South Shetland Is. Abundance were compared with all sub-areas and with some environmental factors such air temperature and ice-cover. The influence between those environmental factors and species distribution is discussed

Occurrence of seabirds and marine mammals in the pelagic zone of the Patagonian Sea and north of the South Orkney Islands

The Patagonian Sea is one of the most productive ecosystems in the Southern Hemisphere. Unlike other coastal regions, however, few studies exist on the top predators in its pelagic zone. In March 2017, a survey of seabirds and marine mammals was carried out on board the R/V Puerto Deseado in the Patagonian Sea, which extends from the South Atlantic Ocean to the north of the South Orkney Islands, Antarctica. Four of the five oceanographic regimes described in this region were studied, and 23 seabird species and five marine mammal species were recorded. Great shearwater Puffinus gravis, Antarctic prion Pachyptila desolata, and fin whale Balaenoptera physalus were the most abundant species. In the 2615 km traveled, two hotspots for top predators were found, coinciding with frontal zones: one in the shelf-break front and the other in the Southern Front of the Antarctic Circumpolar Current. The highest bird diversity and the greatest cetacean concentrations were recorded in the polar regime in the presence of low ice-field debris (5%). The results suggest that at the end of the austral summer, the distribution of top predators in this section of the South Atlantic Ocean is highly unequal. Some oceanic areas have a few species aggregations which contrast with the vast pelagic areas that have scarce species presence and activity. The hotspots were associated with high-productivity areas, but it is likely that they were also facilitated by the time of year (post-reproductive season), as most of the species were concentrated and had fed prior to their migrations

Autumn seabird observations off the South Shetland Islands

Los estudios de aves marinas entre las Islas Shetland del Sur y el norte de la península Antártica son numerosos durante el verano, mientras fuera de esta época son escasos en esta zona. El objetivo de este estudio fue registrar las especies de aves presentes en otoño en la zona comprendida entre el norte de la península Antártica y las islas Shetland del Sur. Las observaciones fueron hechas abordo del Rompehielos Alte. lrizar; se realizaron censos de 10 minutos seguidos de lO minutos de intervalo. durante el fotopedodo. Se calculó el índice de diversidad de Shannon. Fueron registradas 13 especies; se relaciona la aparición de estas aves en la zona en esta época con variables ambientales.SeabirdsSouth Shetland IslandsAntarcticaAutum

The same pathway to the Weddell Sea birdlife, after 65 years: similarities in the species composition, richness and abundances

As part of a multi-year study of top predators in Antarctica, we conducted a seabird shipbased survey on board Almirante Irizar icebreaker in the Weddell Sea to the Filchner Ice Shelf in the austral summer 2020. We carried out 10-minute counts along 1843 km during 125 hours of observation. We analyzed the species distributions and the relationships with the ice cover. We registered 15 species of which four represented more than 85% of the total abundance: Antarctic petrel Thalassoica antarctica (43.9%), snow petrel Pagodroma nivea (16.3%), Arctic tern Sterna paradisaea (15.2%) and emperor penguin Aptenodytes forsteri (10.1%). Species distribution and its relationship with ice cover were analyzed statistically. The ice cover concentration was estimated by using satellite images. We compared our results with the first ship-based bird survey conducted up to the Filchner Ice Shelf in the austral summer 1955/56 to analyze possible changes in the bird community over time. Out of 13 recorded species in the 1955/56 cruise, 11 were present in this study with similar abundance proportions. In both cruises, the bird community consisted of a group of non-numerous species associated with icefree waters and another group of very numerous species associated with high concentrations on ice cover. The similarities between the two cruises, spaced 65 years apart, suggest a temporal persistence of the bird community of the central and the southern Weddell Sea that could be explained by the dynamics of the ice cover and the presence of reproductive colonies within the study site. The current environmental warming is alarming in this bird community because more than 85% of all its individuals belong to four species strongly dependent on ice cover

Approximating home ranges of humpback and fin whales in Drake Passage and Antarctica

Identifying home ranges—those areas traversed by individuals in their normal foraging, mating, and parenting activities—is an important aspect of cetacean study. Understanding these ranges facilitates identification of resource use and conservation. Fin and humpback whales occur in Antarctica during the austral summer, but information regarding their home ranges is limited. Using opportunistically collected whale sighting data from eight consecutive summer seasons spanning 2010–2017, we approximate the home ranges of humpback and fin whales around Drake Passage (DRA), West of Antarctic Peninsula (WAP), South Shetland Islands (SSI), an area northwest of the Weddell Sea (WED), and around the South Orkney Islands (SOI). Approximate home ranges are identified using Kernel Density Estimation (KDE). Most fin whales occurred north and northwest of the SOI, which suggests that waters near these islands support concentrations of this species. Most humpback whales were observed around the SSI, but unlike fin whales, their distributions were highly variable in other areas. KDE suggests spatial segregation in areas where both species exist such as SOI, SSI, and WPA. Partial redundancy analysis (pRDA) suggests that the distributions of these species are more affected by spatial variables (latitude, longitude) than by local scale variables such as sea surface temperature and depth. This study presents a visual approximation of the home ranges of fin and humpback whales, and identifies variation in the effects of space and environmental variables on the distributions of these whales at different spatial scales

New at-sea records of pelagic seabirds in the South Atlantic Ocean and Antarctica

In austral summer 1994-95, 2009, 2010, 2011 and 2012 during a ship-based seabird survey in the south Atlantic and Antarctica we documented at-sea distributions of Buller´s albatross (Thalassarche bulleri), Atlantic petrel (Pterodroma incerta), Softplumaged petrel (P. mollis), Kerguelen petrel (Lugensa brevirostris), and Great-winged petrel (P. macroptera). In some cases, sightings were considered as extralimital but for other species, their distributions need updating. Atlantic Petrel, for example, has been regularly observed in the Drake Passage and north of the Antarctic Peninsula for about 30 years, but the species distribution has not been updated in the literature. Our results will contribute to update the at sea species` distributions and their changes.Fil: Orgeira, Tomás José Luis. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Direccion Nacional del Antártico; Argetnina;Fil: Scioscia, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Cientificas; Argentina;Fil: Torres, Monica Analia. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina;Fil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Cientificas; Argentina

Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea, Antarctica

The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on the Antarctic marine ecosystem and relationships among top predators. This paper presents the results of at-sea monitoring of seabirds and cetaceans over five consecutive summer seasons (2010—2014) in the Scotia Sea, Antarctica. A total of 11 656 flying birds belonging to 24 species were recorded in 884 ten-minute counts. Six Procellariiformes species were abundant: Black-browed Albatross, Cape Petrel, Southern Fulmar, Antarctic Prion, Wilson’s Storm-petrel, and Black-bellied Storm-petrel. Only three of these species accounted for 82% of the total abundance: Antarctic Prion (40%), Southern Fulmar (22%), and Cape Petrel (20%). A total of 678 baleen whales belonging to five species were recorded along a sampling effort of 2 351 nautical miles: Humpback, Sei, Southern Right, Fin, and Minke whales, which had different abundances during the study. The Fin Whale had the highest mean encounter rate for the 5 years (0.29 whales per nautical mile), followed by the Humpback Whale (0.09 whales per nautical mile). Annual dissimilarity in abundance of both seabirds and cetaceans occurred in conjunction with changes in the sea surface temperature and ice cover, showing the dependence of top predators on environmental changes. The largest aggregations of all top predators (seabirds and cetaceans) were recorded in two regions, west and south of the South Orkney Islands, suggesting important prey availability (especially krill) in those areas

Use of an infrared sensor for estimating the nesting densities of Wilson's Storm Petrel in Anctartica

An infrared sensor, as a new method for localization of Wilson's Storm Petrel nests, was tested at Cierva Point, Gerlache Strait, in the Antarctic Peninsula. It detects the heat emitted by breeding birds benneath debris. To test its effectiveness, we used the sensor in an area where nests had already been located, finding 100% ofthe nests. Afterwards, seven eoastal sites with an average area of 548 m' were sampled. The infrared sensor was highly sensitive to the presence of birds benneath rocks; no obvious error sources were found. Besides providing reliable density values, the use of infrared sensors reduced the human impact on colonies because no traumatic methods were used for finding nests

Registros recientes del Petrel Cabeza Parda (<i>Pterodroma incerta</i>) en el Acéano Atlántico Sur y la Antártida

New records of the Atlantic Petrel (<i>Pterodroma incerta</i>) at-sea for the Atlantic region of the Southern Ocean and Antarctica were reported during summer 2009 and 2010. Most of these observations occurred outside the accepted range for this species and improve the available information on its distribution. The Atlantic Petrel has been regularly recorded north and south of the Antarctic Convergence for more than 30 years, although these records are still considered casual and not part of their usual pelagic range.Se reportan nuevos registros obtenidos en el mar del Petrel Cabeza Parda (<i>Pterodroma incerta</i>) en el Océano Atlántico Sur y la Antártida durante los veranos de 2009 y 2010. La mayoría de estas observaciones ocurrieron fuera de las áreas de distribución aceptadas para la especie y mejoran la información disponible acerca de su distribución. El Petrel Cabeza Parda ha sido registrado regularmente al norte y al sur de la Convergencia Antártica por más de 30 años, aunque estos registros aún son considerados ocasionales y no como parte de su distribución pelágica habitual

Presencia de Garcita <i>Bueyera Bubulcus ibis</i> en el Océano Atlántico Sur, otoño de 1993

On May 29,1993,16 individuals of Cattle Egret <i>Bubulcus ibis</i> landed in the deck of a ship in the South Atlantic Ocean, at 290 nautic miles from Malvina Islands and 450 from South Georgia. The birds showed severe reduction of pectoral muscle. Local West-East prevaling winds could have blown the birds from somewhere on the south Argentine coast