168 research outputs found
Delayed start of full incubation is related to a delayed brood patch development in Magellanic penguins
No full textCapsule: Most bird species start full incubation before the clutch is complete, others long after laying the last egg, gradually increasing the incubation temperature as incubation progresses, as is the case in Magellanic Penguins Spheniscus magellanicus. Aims: In this study, we analysed the possible mechanisms underlying this delayed start of full incubation in Magellanic Penguins. We postulated two non-mutually exclusive, possible mechanisms: delayed development of the brood patch and/or variation in the adults’ incubation postures. Methods: We conducted our work at Isla Quiroga, Argentina during 2011–13. We measured the development of the brood patch area, its temperature, the egg temperature and observed the postures of adult penguins. Results: We found no association between the adults’ postures and the delayed start of full incubation, nor between brood patch temperature and the increase in egg temperature as incubation proceeded (egg age). The intercept of the curve between egg temperature and egg age was positively related to brood patch area, while the slope of the curve was negatively related. Conclusion: Our results support the hypothesis that the shape of the curve of the increase in egg temperature as incubation proceeds is a consequence of the increase in the extension of the brood patch area.Fil: Barrionuevo, Melina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Magellanic penguin (Spheniscus magellanicus) embryos tolerate high temperature variations and low temperatures during incubation
No full textMaintaining appropriate developmental temperatures during avian incubation is costly to the parents, so embryos may experience pronounced variations in temperature that can lead to embryo mortality and extended incubation periods, or that could affect the offspring phenotype in several bird species. The egg temperatures (N = 28 eggs) of free-living Magellanic Penguins (Spheniscus magellanicus) were recorded in a breeding colony in Puerto Deseado, Santa Cruz, Argentina. Three nests had atypical incubation patterns. Two nests experienced high temperature drops (average = 11.7 °C, minimum = 6.5°C, duration = 9 h) and another nest had a broad daily temperature range (max-min), i.e. 13.9 ±0.9 °C for the first egg and 14.1 ±0.8 °C for the second egg (range = 8-22°C during egg laying and 1837°C during advanced incubation). Thermal anomalies during incubation did not affect the embryonic viability, hatchling mass or fledging success. The survival of embryos despite these atypical incubation patterns may be an adaptive mechanism during the harsh weather conditions normally experienced by eggs throughout incubation.Fil: Barrionuevo, Melina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Wildlife Conservation Society; Estados Unido
Reply to “Comment on population trends of southern rockhopper penguins (Eudyptes chrysocome chrysocome) on Isla Pingüino, Santa Cruz, Argentina” by Nina Dehnhard
No full textNota corta en respuesta a un comentario publicado por N. Dehnhard.Fil: Gandini, Patricia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Millones, Ana. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Morgenthaler, Annick. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Frere, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin
Environmental Factors Affecting the Distribution of the Red-Legged Cormorant in Argentina: A Regional Scale Approach
No full textRed-legged Cormorants (Phalacrocorax gaimardi) breed along a broad stretch of the Pacific coast and a section of the Argentinian coast on the Atlantic Ocean. To understand factors that might determine the breeding range along Argentina, physical and environmental characteristics of cliffed coastlines used by Red-legged Cormorants were compared with those not used. Red-legged Cormorant colonies were found in longer cliffed coastlines (mostly longer than 250 m) with shallow waters (median depth =12 m) and high sea productivity close to the coast (median chlorophyll a concentration = 4.4 mg/m3). Within the Red-legged Cormorants' breeding range the probability of occurrence of their colonies increased with the length of the cliffed coastline and decreased with the median sea depth around the colony. Mixed colonies were found in coastal areas with cliffs where the seawater close to shore was deeper (deeper than = 13 m). North of its distribution, sea productivity close to the coast was lower (median chlorophyll a concentration = 1.6 mg/m3) than within its distribution, and cliff faces were more exposed to the strong prevailing winds, which can blow eggs and chicks from their nests. South of its distribution, the climatic characteristics were more adverse to breeding success: higher precipitation, lower ambient temperature, and higher wind speed than within its distribution. At this scale of study (regional), new aspects of habitat structure of the Red-legged Cormorant, such as sea primary production, water depths and climatic features, were indentified. All these aspects could be affecting habitat selections by this species.Fil: Millones, Ana. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Parental investment in eggs and its effect on nestling growth and survival in Magellanic Penguins
No full textLife-history variables evolve in response to cost-benefit trade-offs. For birds, larger eggs are thought to be beneficial for development of offspring but are energetically costly to produce. Further, egg-size dimorphism within or between clutches can vary with proximate and ultimate causes. We undertook a correlational study to evaluate parental investment in eggs by Magellanic Penguins (Spheniscus magellanicus) and how it affects the growth and survival of nestlings in Puerto Deseado, Argentina, over 3 years. We evaluated the variables that affected egg-volume and yolk-area (using a nondestructive technique), and determined the effects of egg-volume and yolk-area on growth and survival of young. Females in good body-condition laid larger second eggs and, in good years (i.e. years of high reproductive success in the colonies of the study area), yolk-area of second eggs was larger than that of first eggs. We found a positive association between egg-volume and nestling body-size and yolk-area was positively related to nestling survival. Our results suggest that the size of eggs within clutches varied with year and female body-condition. Moreover we demonstrate for the first time that yolk-area is a strong predictor of nestling survival in Magellanic Penguins.Fil: Barrionuevo, Melina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Blood-specific isotopic discrimination factors in the Magellanic penguin (Spheniscus magellanicus)
No full textRATIONALE: The use of stable isotopes for ecological studies has increased exponentially in recent years. Isotopic trophic studies are based on the assumption that animals are what they eat plus a discrimination factor. The discrimination factor is affected by many variables and can be determined empirically. The Magellanic penguin is a highly abundant marine bird that plays a key role in the southern oceans. This study provides the first estimation of the Magellanic penguin blood discrimination factor for (13) C and (15) N.Fil: Ciancio Blanc, Javier Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Righi, Carina. Fundacion Temaikèn, Departamento de Conservación e Investigación; ArgentinaFil: Faiella, Adrián. Aquarium Mar del Plata; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. BirdLife International; Argentin
How Nest Site Characteristics Influence Breeding Success in Red-legged Cormorants Phalacrocorax gaimardi
No full textFor seabirds, nest site features are an important factor that determines reproductive success. During three breeding seasons (2010-2012), we visited two coastal cliff colonies of Red-legged Cormorants halacrocorax gaimardi in the Ría Deseado, Argentina, and studied how nest site characteristics influenced their breeding success. We measured six physical characteristics at 46 nest sites, and we counted the number of fledglings produced each year from each nest (breeding success). We also related nest site temperature and wind exposure with nest site orientation. Breeding success was higher at nest sites with a broad base (greater capacity for holding young) and at nests that were less exposed to winds greater than 25 knots (46.25 km/h), which were sites with a north orientation. The lowest breeding success was observed in nest sites that were exposed to the strongest winds (i.e., sites with a south orientation). Strong winds often blow eggs and chicks away from the nests and increase opportunistic predation by gulls Larus sp. No significant relationship was found between nest site orientation and nest site temperature. Breeding success decreased with the distance to the nearest nest, which agrees with the idea that higher density of reproductive individuals reduces effectiveness of predators. Nest cover, distance from the top of the cliff, and distance from the tide line had no effect on breeding success at this study scale. Our results suggested that nest site haracteristics that were related to protection against adverse weather conditions (e.g., strong winds) and avian predation, in combination with a suitable nest space, determined the breeding success of Red-legged Cormorants.Fil: Millones, Ana. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Frere, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin
Egg temperature and initial brood patch area determine hatching asynchrony in Magellanic Penguin Spheniscus magellanicus
No full textIn birds, the adaptive significance of hatching asynchrony has been under debate for many years and the parental effects on hatching asynchrony have been largely assumed but not often tested. Some authors suggest that hatching asynchrony depends on the incubation onset and many factors have been shown to influence hatching asynchrony in different species. Our objective was to analyze the exact timing of the onset of incubation and if this affects hatching asynchrony; and, in addition, which other factors (brood patch development, incubation position, adult body condition, intra-clutch egg dimorphism, laying date and year) affect hatching asynchrony in Magellanic penguins Spheniscus magellanicus. We first estimated the eggshell temperature at which embryo development starts, with a non-destructive and novel method. We then recorded individual egg temperatures in 61 nests during incubation, and related them, and other breeding parameters, to hatching asynchrony. We also observed incubation positions in 307 nests. We found a significant positive relationship between hatching asynchrony and the temperature that the first-laid egg experienced during egg laying and between hatching asynchrony and the initial brood patch area. We also found a negative relationship between hatching asynchrony and the difference in temperature between second and first-laid eggs within a clutch, measured after the egg-laying period was finished. We ruled out position of the eggs during incubation, adult body condition, egg volume, laying date, and study year as factors influencing hatching asynchrony. The egg temperature during laying and the difference in temperature between eggs of a clutch are determinants of hatching asynchrony in Magellanic penguins.Fil: Barrionuevo, Melina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Predicting the Sex of Kelp Gulls by External Measurements
No full textMale and Female of Kelp Gulls (Larus Dominicanus) are not clearly sexually dimorphic and are thus difficult to identify in the field. This paper evaluates sexual size dimorphism in this species and provides a reliable method for predicting the sex of measured individuals. Discriminant analysis of six morphometric characters of adult birds indicated that head lenght, bill lenght and bill depht were the most accurate variables for use in a discriminant function model, predicting sex with 97% accuracy.Fil: Torlaschi, Chantal. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Gandini, Patricia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Frere, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Martinez Peck, Rolando. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin
Turismo sustentable y cambios de política para la poblaciónes indígenas: el caso de Yariguarenda (Salta, Argentina)
No full textThe author considers the emergence of rural and community tourism in the Argentine village of Yariguar-enda. She reflects on implementing some policies aimed at the indigenous population and on the gradual affirmation of the enhancement of cultural diversity, albeit in a context with a robust neoliberal incidence. She also examines the tensions between the struggle to recoverLa autora considera el surgimiento del turismo rural y comunitario en el pueblo argentino de Yariguarenda. Reflexiona sobre la implementación de algunas políticas dirigidas a la población indígena y sobre la paulatina afirmación de la valorización de la diversidad cultural, aunque en un contexto de fuerte incidencia neoliberal. Examina las tensiones que surgen entre la lucha por la recuperación de la identidad indígena y el medio ambiente, y la voluntad política de hacer de ese territorio un “producto turístico”.L’autrice considera l’affermarsi del turismo rurale e comunitario nel villaggio argentino di Yariguarenda. Riflette sull’implementazione di alcune politiche rivolte alla popolazione indigena e sull’affermarsi gra-duale della valorizzazione delle diversità culturali, seppur in un contesto a forte incidenza neoliberista. Esamina le tensioni che scaturiscono tra la lotta per il recupero della identità indigena e dell’ambiente, e la volontà politica di fare di quel territorio un “prodotto turistico”
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