Selfies of imperial cormorants (Phalacrocorax atriceps): What is happening underwater?

During the last few years, the development of animal-borne still cameras and video recorders has enabled researchers to observe what a wild animal sees in the field. In the present study, we deployed miniaturized video recorders to investigate the underwater foraging behavior of Imperial cormorants (Phalacrocorax atriceps). Video footage was obtained from 12 animals and 49 dives comprising a total of 8.1 h of foraging data. Video information revealed that Imperial cormorants are almost exclusively benthic feeders. While foraging along the seafloor, animals did not necessarily keep their body horizontal but inclined it downwards. The head of the instrumented animal was always visible in the videos and in the majority of the dives it was moved constantly forward and backward by extending and contracting the neck while travelling on the seafloor. Animals detected prey at very short distances, performed quick capture attempts and spent the majority of their time on the seafloor searching for prey. Cormorants foraged at three different sea bottom habitats and the way in which they searched for food differed between habitats. Dives were frequently performed under low luminosity levels suggesting that cormorants would locate prey with other sensory systems in addition to sight. Our video data support the idea that Imperial cormorants' efficient hunting involves the use of specialized foraging techniques to compensate for their poor underwater vision.Fil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Yoda, Ken. Nagoya University; JapónFil: Zavalaga, Carlos. Universidad Científica del Sur; Perú. Nagoya University; JapónFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Wildlife Conservation Society; Estados Unido

Leg rings impact the diving performance of a foot-propelled diver

Leg rings are frequently used to mark aquatic birds in order to identify individuals, and study population dynamics and migration patterns, with the proviso being that the rings should not affect the birds. The effects of tags and rings are of particular interest in diving birds because any change in body shape could impact swimming efficiency and costs, as water is almost a thousand times denser than air. We attached tri-axial accelerometers to both ringed and unringed breeding Imperial Shags Leucocarbo atriceps to assess dive performance based on descent angle, descent rate, power stroke rate, power stroke peak acceleration amplitude and Vectorial Dynamic Body Acceleration (VeDBA) as a proxy for energy expenditure. Ringed birds, especially females, had a higher foot-stroke amplitude than unringed animals. In addition, the overall efficiency of the ringed individuals, as expressed by the descent rate per unit VeDBA, was compromised (by 3.5% in females and 4.3% in males) compared with unringed birds. We conclude that leg rings change the diving performance of Imperial Shags, although the effect is small and may not affect reproductive success. However, given that birds are typically ringed for life, we urge researchers to be particularly careful about the potential cumulative effect of attaching leg rings to foot-propelled diving species.Fil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Pantano, Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Wilson, Rory P. Swansea University. College Of Sciences. Departament Of Biosciences; Reino UnidoFil: Svagelj, Walter Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Yoda, Ken. Nagoya University; JapónFil: Gunner, Richard. Swansea University. College Of Sciences. Departament Of Biosciences; Reino UnidoFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Spatio-temporal variation in mortality rates of White-chinned Petrels Procellaria aequinoctialis interacting with longliners in the south-west Atlantic

The White-chinned Petrel Procellaria aequinoctialis is the second most commonly captured species by Argentinean longliners. The severe declines that this species has experienced in some of its populations (e.g. South Georgia Islands) have been principally attributed to incidental mortality associated with longliners. In this study we analyse the spatio-temporal variability in the mortality rates of White-chinned Petrels on the Patagonian Shelf and the effects that environmental and operational variability have on such mortality. The average capture rate (¡ 1 SD) for the period 1999–2003 was 0.014 ¡ 0.090 White-chinned Petrels for every 1,000 hooks deployed. Higher capture rates were observed when short longlines were deployed. Capture rates were not affected by the wind speed or by the time to the full moon. The distribution of the captures differed throughout the year. During autumn–winter most captures took place in the north of the Patagonian Shelf, whereas during spring–summer incidental captures occurred principally to the south between 45uS and 50uS.El Petrel Barba Blanca Procellaria aequinoctialis constituye la segunda especie ma´s frecuentemente capturada por la flota palangrera Argentina. Los importantes decrecimientos poblacionales observados en algunas poblaciones de esta especie (e.g. Islas Georgias del Sur) han sido principalmente atribuidos a la mortalidad incidental asociada a embarcaciones palangreras. En este trabajo se analizo´ la variacio´n espacio- temporal en las tasas de captura incidental del Petrel Barba Blanca a lo largo de la Plataforma Continental Argentina y se estudio´ el efecto que diferentes variables ambientales y operacionales tienen sobre la mortalidad incidental de esta especie. La tasa de captura promedio (¡ d.s) durante el periodo 1999–2003 fue de 0.014 ¡ 0.090 Petreles Barba Blanca cada 1.000 anzuelos. Mayores tasas de captura fueron registradas al utilizar palangres cortos. No se observo´ un efecto de la intensidad del viento ni de la distancia a la luna llena sobre las tasas de captura. La distribucio´n de las capturas difirio´ a lo largo del an˜ o. Durante el oton˜ o-invierno la mayorı´a de las capturas estuvieron localizadas al norte de la Plataforma Continental Argentina, mientras que durante los meses de primavera-verano las capturas estuvieron localizadas principalmente entre los 45uS y 50uS.Fil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: Favero, Marco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentin

Insights into the Foraging Behavior of Magellanic Penguins (Spheniscus magellanicus)

Between 25-30 November 2013, 2014 and 2015, miniaturized video cameras were attached to Magellanic Penguins (Spheniscus magellanicus; n = 14) in Punta Norte/San Lorenzo, Península Valdés, Chubut, Argentina. The objective was to examine prey selection, consumption of untraceable prey, and inter- and intraspecific interactions. During 56.3 hr of video footage, 1,621 dives from 14 individuals were recorded. Magellanic Penguins swam through shoals of lobster krill (Munida gregaria morph subrugosa), selectively consuming the fish, primarily anchovies (Engraulis anchoita), that were dispersed along the shoal, but did not consume the lobster krill. Magellanic Penguins captured fish on dives of less than 2 m in depth. The tagged individuals foraged with conspecifics in 2% (n = 33) of the total recorded dives. In addition, a multispecies feeding association was also documented (n = 1). Results were constrained to the upper 40 m of the water column; below this depth light level was too low for detections by video. The development of cameras with a light source and wider-angle lens are crucial to improve our understanding of Magellanic Penguin foraging behavior.Fil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Yoda, Ken. Nagoya University;Fil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Use of natural and anthropogenic resources by Olrog's Gull Larus atlanticus: Implications for the conservation of the species in non-breeding habitats

We studied the exploitation of crab-beds and fishing grounds by Olrog's Gulls Larus atlanticus in non-breeding areas along the coast of Buenos Aires province, Argentina. During 2004 and 2005, censuses were performed in different areas of Mar Chiquita coastal lagoon and Mar del Plata harbour. Additionally, from April to August 2005 the movements of five non-breeding individuals were studied by means of radio-telemetry. At both study sites the highest numbers of Olrog's Gulls were observed between June and August. A total of 278 radio-tracked locations (from 407 samples) were registered. All the tracked individuals showed strong site fidelity, with 96% of the radio signals registered in the vicinity of the lagoon's mouth, associated with both crab-beds and areas where sport-fishing activities took place. Conservation issues in non-breeding areas should be tackled in the near future, given the conservation status of this species (Vulnerable) and the fact that each year several Olrog's Gulls are being killed because of their interaction with sport-fishing activities.Fil: Beron, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: Favero, Marco. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentin

The eldest sibling is the lousiest in an obligate brood reducer seabird

Previous studies on vertical transmission of lice on terrestrial birds have shown that the intensity of parasitism can vary within broods in relation to the hatching order of chicks. In species where the hatching order has an important effect on chick survival, lice would benefit from living on the host with the highest survival prospects. In the present work, we test this hypothesis using as model lice from the Imperial Shag, an obligate brood reducer. Our specific aims were to investigate how infestation of Eidmanniella pellucida varies in relation to the age, the order of birth and the hatching date of chicks. We observed that chicks were infested by their parents during their first days of life, mainly by lice in nymphal stage. The first chick to hatch was the most infested. Infestation was also affected by hatching date, increasing as the season progressed, reaching a maximum at the peak of the breeding season and decreasing gradually after that. The age of the chick was unrelated to the intensity of infestation. Our results suggest that lice would prefer the chick that is more likely to survive and highlights the adaptive strategies of lice according to the ecology of their hosts.Fil: Leonardi, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Svagelj, Walter Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Habitat use and characterization of the seascape exploited by wintering adult and juvenile Southern Giant Petrels from Patagonia

The characterization of the seascape used by top predators helps to understand the functioning of marine systems. The main goals of this study were to 1) analyze habitat use and at-sea movements of adult and first year juvenile southern giant petrels (SGP, Macronectes giganteus) during the austral winter, and 2) to characterize the oceanographic and biological features of their marine environment.Fil: Blanco, Gabriela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Pisoni, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina2nd World Seabird ConferenceCape TownSudáfricaWorld Seabird UnionAfrican Seabird Grou

Intersexual differences in the diving behaviour of imperial cormorants

Intersexual differences in the foraging behaviour have been examined in several seabird species, especially those exhibiting sexual size dimorphism. We studied intersex behavioural differences in the Imperial Cormorant (Phalacrocorax atriceps), a size dimorphic seabird. Twenty adults (11 females and 9 males), breeding at Punta León (43°04′S; 64°2′W), Chubut, Argentina, were equipped with loggers to measure tri-axial acceleration and depth, to calculate the foraging trip time/activity budgets and diving behaviour. Both sexes had similar foraging trip durations, spending a similar proportion of the foraging time flying and floating on the sea surface. However, females spent more time underwater, executing more and shallower dives. Females also recovered more quickly than males from dives performed to depths of less than 30 m and spent more time foraging along the bottom at any depth than males. We conclude that if allometric effects affect the foraging behaviour of Imperial Cormorants, they only do so during diving because no differences were observed in the total amount of time sexes spent flying or foraging.Geschlechtsunterschiede bei der Nahrungsaufnahme wurden bereits für mehrere Seevögel beschrieben, besonders für solche mit geschlechtsabhängiger Körpergröße. Wir untersuchten geschlechtsspezifische Verhaltensunterschiede bei der Blauaugenscharbe, einem Seevogel mit geschlechtsbedingt unterschiedlicher Körpergröße. Achtundzwanzig adulte Tiere (11 Weibchen, 9 Männchen), die bei Punta León (43°04′S; 64°2′W), Chubut, Argentinien, brüteten, wurden mit Datenloggern zur Aufzeichnung ihrer drei-achsigen Beschleunigung und Tauchtiefe versehen, um ihre Zeit- und Aktivitäts-Budgets und ihr Tauchverhalten zu messen. Beide Geschlechter verbrachten etwa gleich viel Zeit bei ihren Ausflügen zur Nahrungssuche, mit in etwa auch gleich großen Zeit-Anteilen für Fliegen und Treiben auf dem Wasser. Aber die Weibchen verbrachten mehr Zeit unter Wasser bei häufigeren Tauchgängen in flacherem Wasser. Sie erholten sich auch rascher als die Männchen von Tauchgängen in Tiefen bis zu 30 Meter und verbrachten in jeder Tiefe mehr Zeit als die Männchen bei der Nahrungsaufnahme am Grund. Wir schließen hieraus, dass, wenn allometrische Effekte das Nahrungsaufnahme-Verhalten von Blauaugenscharben überhaupt beeinflussen, diese Einflüsse nur beim Tauchen auftreten, da in der Zeit, die fliegend oder für die Nahrungsaufnahme verbracht wurde, kein Geschlechtsunterschied festgestellt werden konnten.Fil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Quintana, Flavio Roberto. Wildlife Conservation Society; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Shepard, E. L. C.. University of Wales; Reino UnidoFil: Wilson, R. P.. University of Wales; Reino Unid

Buoyed up and slowed down: Speed limits for diving birds in shallow water

In air-breathing animals, the time and energy costs of each dive are primarily determined by depth-related upthrust, swim speed and temperature. While studies have previously investigated how animals should optimise their behaviour in relation to either upthrust or speed they have rarely been examined in tandem. We took overall dynamic body acceleration (ODBA) as a proxy for the mechanical power used during the bottom phases of dives of imperial shags Phalacrocorax atriceps, as these birds forage benthically, in order to define: (1) the minimum power required for swimming at depth and (2) how the use of power above this threshold varied with dive depth.   Results showed that ODBA declined with increasing dive depth in a manner correlated with the reduction in upthrust, and that the use of power above that required for prey searching increased with increasing dive depth. This may constitute a response to depth-related patterns in prey  availability. We present a model to investigate an alternative hypothesis that the ability of birds to produce burst speeds is also inversely related to the power required to counter buoyancy. Under the model assumptions, achievable burst speeds vary up to 0.7 m s–1 across dive depths from 5 to 60 m. Ultimately, prey preferences cannot be separated from prey fields, but we suggest that this model may provide insight into the ability of air-breathing divers to pursue various prey types according to dive depth.Fil: Shepard, Emily L. C.. Swansea University; Reino UnidoFil: Wilson, Rory P.. Swansea University; Reino UnidoFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados Unido

Sex-specific environmental sensitivity on the postnatal growth of a sexually size-dimorphic seabird

The environment experienced during development is a key factor determining intraspecific variation in postnatal growth. In sexually size-dimorphic species, the larger sex typically grows at a higher absolute rate and consequently is more sensitive or vulnerable to restrictive environments. In addition, this sensitivity can be intrinsic when it is caused by physiological disadvantages of the larger sex, or extrinsic when it results from environments generated by social interactions among siblings. Here, we evaluated intrinsic and extrinsic drivers of sex-specific sensitivity in the postnatal growth of the Imperial Shag Leucocarbo atriceps, a sexually dimorphic seabird that typically produces one- or two-fledgling broods. Our objectives were to evaluate sex-specific effects of: (1) good and poor years on chicks fledging as singletons, (2) different rearing environments produced by the combinations of brood size and hatching order, and (3) sibling sex and brood sex composition in two-fledgling broods. Singletons exhibited suboptimal growth in poor years, with males and females equally affected. At an extrinsic level, males were more sensitive than females, as the reduction in fledging mass between best and worst social environments was twice as high in males as in females. In addition, the presence of a younger sibling in the nest had sex-specific consequences for the older chick. Fledging mass of older female chicks was unaffected by the presence of a younger sibling, whereas males reached the highest fledging mass when raised as singletons. The sex of the sibling and the brood sex composition did not affect chick growth in two-chick broods. Overall, our results suggest that females grow at their maximum rate even in moderately favourable social environments (as senior chicks in two-chick broods), whereas males require the most favourable environment (raised as singletons) to reach the highest growth.Fil: Svagelj, Walter Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Pérez, María Rita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Somoza, Gustavo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin