Seasonally persistent foraging niche segregation between sympatric Southern Rockhopper and Magellanic penguins breeding at Isla de los Estados, Argentina

Variation in the foraging strategies used among species is a key factor in determining the trophic structure of ecological communities. Moreover, foraging niche differentiation could be driven by inter-specific competition and/or variation within species due to seasonal, age, sex and/or individual factors. Using stable isotope analysis, we assessed inter- and intra-specific differences in the foraging niches of female Southern Rockhopper penguin (Eudyptes chrysocome; SRP) and male and female Magellanic penguins (Spheniscus magellanicus; MP) at Isla de los Estados, Argentina. We sampled whole blood and feathers from breeding adults, representing the breeding and pre-moult periods over two consecutive years (2012 and 2013). We also compared stable isotope values between tissue to test for consistency in individuals foraging niches and the potential for foraging niche specialisation and segregation within breeding pairs. We observed clear foraging niche segregation between species that persisted during both breeding and pre-moult periods. SRP foraged in more oceanic/pelagic waters (lower δ13C values) while MP used coastal/benthic foraging habitats (higher δ13C values). In addition, SRP fed on lower trophic level prey (low δ15N values) relative to MP during both time periods. The isotopic foraging niches of MP highly overlapped between sexes at the population level and there was little to no evidence of niche segregation within breeding pairs or individual consistency in the seasonal foraging niche of both species. The results suggest that inter-specific foraging niche segregation is likely a more important factor influencing the trophic ecology and foraging behaviours of these species, relative to intra-specific factors. Even so, the persistence of inter-specific foraging niche segregation outside the breeding season suggests that either the potential for competition for food resource or foraging habitats remain high during this time or that the ultimate factors responsible for foraging niche segregation among these two species may be unrelated to these proximate factors.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Polito, Michael J. Lousiana State University; Estados UnidosFil: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentin

Brote de botulismo tipo C en aves acuáticas del Lago Nahuel Huapi y área del Parque Nacional, Argentina

An outbreak of avian botulism type C occurred at the Kelp Gull (Larus dominicanus) colonies located at the Nahuel Huapi National Park and lake area in Argentina, at the end of the breeding season, during austral summer 2020. While conducting fieldwork, birds were observed with paralysis of the lower and upper limbs, and dead birds were found in a sitting down position with no signs of having been attacked. We collected blood and tissue samples from eight Kelp Gulls and one Ashy-headed Goose (Chloephaga poliocephala) for toxicological analysis. One sample of Ashy-headed Goose resulted positive for botulinum toxin type C. Diseases like botulism are usually lethal for wildlife and have important effects on bird populations. Though the impact on the Kelp Gull colonies did not seem to be of great concern (~2.3% of the population affected), specific research into the source of the toxin and the initiating conditions are required to understand the potential threats to the environment and to different bird populations that live in this area. This would be key for aquatic bird species such as the Ashy-headed and the Upland Goose (C. picta), both considered threatened in Argentina.Un brote de botulismo tipo C ocurrió en la zona lacustre del Parque Nacional Nahuel Huapi en Argentina al final de la temporada reproductiva durante el verano austral del 2020 en las colonias de Gaviota Cocinera (Larus dominicanus). Mientras se realizaban tareas de campo, se observaron aves con parálisis de los miembros inferiores y superiores y aves muertas en posición sentada sin signos de haber sido atacadas. Recolectamos muestras de sangre y tejidos de ocho Gaviotas Gocineras y un Cauquén Real (Chloephaga poliocephala) para análisis toxicológicos. Una de las muestras de Cauquén Real resultó positiva para botulismo de tipo C. Enfermedades como el botulismo son consideradas letales para la fauna silvestre y tienen importantes efectos en las poblaciones de aves. Aunque el impacto registrado en las colonias de Gaviota Cocinera no fue de gran preocupación (~2.3% de la población afectada), se requieren estudios específicos que permitan detectar la fuente de la toxina y las condiciones iniciales, para poder entender las posibles amenazas al ambiente y a las diferentes poblaciones de aves que habitan en el área. Esto será clave para especies acuáticas como el Cauquén Real y el Cauquén Común (C. picta), ambas consideradas como amenazado en Argentina.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Cossa, Natalia Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. 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. Aves Argentinas. Programa Patagonia; ArgentinaFil: Farace, María Isabel. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Ojeda, Valeria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Seijas, Susana. Ministerio de Ambiente y Desarrollo Sustentable. Administración de Parques Nacionales. Parque Nacional "Nahuel Huapi". Departamento Conservación y Educación Ambiental; Argentin

Where’s the best supermarket deal? Female Southern Rockhopper Penguins (Eudyptes chrysocome) show variable foraging areas during the guard stage at Isla de los Estados, Argentina

Understanding the spatial distribution of seabirds contributes to comprehending their ecological requirements and dispersion patterns. We studied the at-sea distribution of female Southern Rockhopper Penguins (Eudyptes chrysocome (J.R. Forster, 1781)) at Isla de los Estados colony during the early chick-rearing period. We used a clustering analysis approach to identify different groups according to the foraging trip (tracking and diving data from GPS and temperature and depth data loggers) and diet (d15N composition on blood samples) characteristics. Foraging trips differed in duration, location, and dive depths explored. Females in clusters 1 and 3 traveled longer distances and in opposite directions (36.3 6 21.3 and 40.3 6 14.0 km, respectively). Females in cluster 2 fed closer to the colony (16.8 6 7.8 km). Dives occurred in pelagic habitats. Higher d15N values suggested a greater proportion of fish (e.g., the Fuegian sprat, Sprattus fuegensis (Jenyns, 1842)) consumption in the northern foraging areas (cluster 1). The variability observed in the spatial distribution suggests flexibility in the foraging behavior of Southern Rockhopper Penguins and availability of adequate foraging areas within the colony range during the early chick-rearing period, both important features for Southern Rockhopper Penguin population. These results contribute to understanding the use of the Southern Ocean by marine mesopredators and top predators and to the marine spatial planning in the area.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Pütz, Klemens. Antarctic Research Trust; AlemaniaFil: Polito, Michael J.. State University of Louisiana; Estados UnidosFil: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentina. Wildlife Conservation Society; Estados Unido

Foraging behavior of southern rockhopper penguin Eudyptes chrysocome and Magellanic penguin Spheniscus magellanicus at Isla de los Estados, Tierra del Fuego, Argentina

El comportamiento de alimentación y dieta de las aves marinas, engeneral, varía con la localidad, el sexo y el estadio del ciclo anual. Además, en una misma región pueden alimentarse distintas especies con requerimientos tróficos similares, aunque no podrían co-existir sin diferencias ecológicas (principio de exclusión competitiva). Así, estudiar la segregación inter- e intra-específica es relevante para entender la estructura y funcionamiento de estas comunidades. Dos especies de pingüino anidan en simpatría en Bahía Franklin, Isla de los Estados, el pingüino penacho amarillo del sur Eudyptes chrysocome (PPA) y el pingüino de Magallanes Spheniscus magellanicus (PM). El objetivogeneral de esta tesis fue estudiar las áreas de alimentación, las estrategias de búsqueda de alimento y el uso de la columna de agua y el nivel trófico durante distintas etapas del ciclo anual de dichas especies y sus diferencias inter- e intra-específicas. El estudio serealizó durante tres temporadas reproductivas (2011?2013), utilizando registradores con sensores de posicionamiento satelital, profundidad y temperatura, modelados en un sistema de información geográfico e isótopos estables. Los PM mostraron leves diferencias entre sexos en su comportamiento de buceo y una gran superposición en las áreas del marutilizadas para alimentarse. También se registró variabilidad inter-anual en el comportamiento alimentación y el nivel trófico de la especie, aunque no se reflejó en una menor supervivencia de los pichones. Por su parte, las hembras de PPA mostraron segregación intra-específica en la población, utilizando distintas áreas de alimentación yzonas en la columna de agua, durante la etapa de cuidado temprano de pichones. Durante la etapa de cuidado tardío, los análisis de isótopos estables de PPA mostraron un comportamiento de aprovisionamiento selectivo, siendo los pichones alimentados con presas de mayor calidad energética que las que ingieren sus padres; aunque no se observaron diferencias en las áreas utilizadas por los adultos para auto-aprovisionamiento y aprovisionamiento de los pichones. Los nichos isotópicos de ambas especies mostraron una fuerte segregación inter-específica durante la etapa de cuidado temprano, reduciendo la competencia durante esta etapa, en la que están restringidos a explotar recursos dentro de un área limitada. Las hembras de PPA se alimentaron en un nivel trófico menor y en aguas abiertas en comparación con los PM, que se alimentaron en un nivel trófico mayor y en aguas costeras. Fuera de la temporada reproductiva, durante el viaje de pre-muda, semantuvo la segregación inter-específica en las áreas utilizadas para alimentarse y el nivel trófico, prevaleciendo las diferencias ecológicas observadas dentro la temporada de cría en el comportamiento de alimentación de ambas especies en esta localidad. Este estudio aporta aspectos novedosos sobre el comportamiento y la ecología trófica de las dos especies de pingüinos que viven en simpatría en Isla de los Estados. Además, resulta importante para comprender el funcionamiento del ecosistema marino del Atlántico Sudoccidental a través de sus predadores tope, y para realizar futuras acciones de conservación en el área de estudio, a través de la información sobre las áreas de importancia para los pingüinos en la región.Foraging behavior and diet of seabirds, in general, varies with locality, sex and the life stage. Also, different species with similar trophic requirements can feed in the same region, though they could not co-exist without ecological differences (principal of competitive exclusion). Studying the inter-and intra-specific segregation is relevantto understand the structure and functioning of this communities. Two penguin species nest in sympatry in Bahia Franklin, Isla delos Estados, southern rockhopper penguins Eudyptes chrysocome(RHP) and Magellanic penguins Spheniscus magellanicus(MP). The general objective of this thesis was to study the foraging areas, search for food strategies, the use of the water column and trophic level during different stages of the annualcycle of the species mentioned and their inter-and intra-specific differences. The study was carried on during three breeding seasons (2011-2013) using devices with GPS, depth and temperature sensor, modelling in geographic information system and stable isotopes. MP showed small differences between sexes in their diving behavior and great overlap in the foraging areas at sea. Even though they showed inter-annual variability in the foraging behavior and the trophic level, it was not reflected in a smaller survival of the chicks. On their behalf, female RHP showed intra-specific segregation in the population, using different foraging areas and zones in the water column, during the early chick rearing period. During the late chick rearing period, stable isotope analysis on RHP showed a selective provisioning behavior, being the chicks fed with higher quality prey type than their parents; though no differences were found in the foraging areas used for adult self-provisioning and chick provisioning. Isotopic niche of both species showed a strong inter-specific segregation during early chick rearing period. Female RHP fed on a lower trophic level and off-shore compared to MP that fed at higher trophic level and in coastal areas. Outside the breeding season, during the pre-molt trip, the inter-specific segregation in the foraging areas and trophic level was maintained, suggestingthat the ecological differences observed in the foraging behaviourduring the breeding season prevailed on this location. This study shows novel aspects of the behavior and trophic ecology of the two species of penguins that live in sympatry on Isla de los Estados. Also, it is important to understand how the South-Atlantic marine ecosystem works though their top predators and for future conservation actions regarding marine protected areas for penguins in the region.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentin

What´s for dinner mom? Selective provisioning in southern rockhopper penguins (Eudyptes chrysocome)

Breeding seabirds must balance self-care and reproduction, especially once offspring have hatched and have to be fed regularly. Seabirds may selectively provision chicks with higher quality food than they consume themselves. In contrast, adults may prioritize their survival rather than their progeny by feeding chicks with lower quality prey items than they feed themselves. We examined the parental provisioning strategies of southern rockhopper penguins at Isla de los Estados in 2012 using nitrogen (δ15N) and carbon (δ13C) stable isotope analysis to determine if selective provisioning and foraging habitat differences exist between parents and their offspring. We found that chicks had higher δ15N values compared to both male and female penguins, and female had slightly higher δ15N values compared to male penguins. There was also a strong positive relationship in δ15N values between female penguins and their offspring, indicating that chicks? diet resembles the female parent more than the male parent. Our results support the hypothesis of selective provisioning of chicks with higher trophic level (i.e., δ15N value) prey and the observation that females exclusively feed chicks during the guard stage. We did not find differences in δ13C values between adult and chicks suggesting no differences in the areas or habitats used to forage for self-provisioning and chick-provisioning. These findings likely have broader significance as provisioning rates and quality of food consumed by chicks is often strongly related to chick growth and survival.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Polito, Michael J.. Louisiana Tech University; Estados UnidosFil: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentin

Do penguins share? Evidence of foraging niche segregation between but not within two sympatric, central-place foragers

Niche theory predicts that sympatric species should differentiate ecologically in order to co-exist and conspecifics will also differentiate to reduce intra-specific competition. As central-place foragers, colonial breeding seabirds represent an ideal model system to test this theory and examine the mechanism of niche segregation. We used GPS-TDlog devices for tracking and diving data and stable isotope analysis to examine patterns of inter- and intra-specific niche segregation among southern rockhopper penguins Eudyptes chrysocome chrysocome and Magellanic penguins Spheniscus magellanicus breeding on Isla de los Estados, Argentina, across 3 consecutive breeding seasons. Tracking data indicated strong inter-specific spatial segregation of foraging locations and little overlap. Diving data also highlighted vertical foraging niche segregation as female rockhopper penguins dove deeper than male and female Magellanic penguins. δ13C values supported the general pattern of habitat segregation, with lower values for female rock-hopper penguins that dove deeper and foraged off the shelf break. Female rockhopper penguins exhibited a lower relative trophic value (δ15N) than male and female Magellanic penguins, consistent with previous dietary studies of both species. These differences likely act to reduce competition between the 2 species during the breeding season, when they are constrained to exploit the resources around their colonies. In contrast, male and female Magellanic penguins shared a similar foraging niche as measured by areas used to forage, dive depths, relative habitat use and trophic values. The lack of sex-specific foraging niche segregation of Magellanic penguins at Isla de los Estados could be related to the availability of food in the area and/or the small population size.Fil: Rosciano, Natalia Gimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Polito, Michael J. Lousiana State University; Estados UnidosFil: Raya Rey, Andrea Nélida. Universidad Nacional de Tierra del Fuego; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin