Seabird Ecology and Conservation in Northern Patagonia

Seabirds of Golfo San Jorge: Feeding Ecology and Management Implications

Commercial trawl fisheries, represent critical threats to the area’s seabird populations.
"Your contribution is crucial to keep these conservation efforts going, and to help us saving Patagonian seabird populations for future generations."

Development of coastal environments in Argentina during the last decades has brought increasing pressure on coastal wildlife. Habitat modification and disturbance are important threats to many breeding and foraging bird populations, and have led to growing concern due to rapid growth of unregulated tourism, recreation, and resource extraction activities. In addition, growing commercial fisheries and industries that generate pollution are affecting biodiversity in both coastal and pelagic waters. Seabirds are important components of these marine environments, and due to their demographic characteristics and colonial habits they are vulnerable to some human activities.


For a detailed list of requested items and how to contribute to this project.

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For more than twenty years, researchers led by Dr. Pablo Yorio have been monitoring key seabird populations at coastal protected areas and analyzing ecological and human related factors affecting their distribution, abundance and productivity in order to gain knowledge and develop recommendations for their conservation and management. In addition to providing technical advice to government authorities, they produce information that is used to increase public awareness and train students through their participation in conservation-oriented research projects.

Dr. Yorio’s team is currently working in two key areas of the Patagonian coast, which are relevant for their environmental characteristics and seabird breeding assemblages: Golfo San Jorge (Chubut) and Bahía San Blas (Buenos Aires). Read more about these two conservation projects, and on how can you help us protecting seabirds in Patagonia and the South Atlantic Ocean.

The northern sector of the gulf is one of the most important coastal areas in terms of marine biodiversity and one of the priority seabird areas in Argentina. Thirteen of the seventeen Patagonian breeding seabirds nest on islands of this coastal sector, including a significant proportion of the Patagonian population of some of such species (25% of the Near Threatened Magellanic Penguin Spheniscus magellanicus, 80% of the Southern Giant Petrel Macronectes giganteus and 25% of the Imperial Cormorant Phalacrocorax atriceps). It is also one of the two breeding grounds of the threatened Olrog’s Gull (Larus atlanticus). Recognition of the environmental value of this area has resulted in its recent designation as the Patagonia Austral Marine Park. For the last decade, our project has been obtaining ecological information on key seabird species and on spatial conflicts between seabirds and human activities to encourage the designation and planning of Golfo San Jorge as a marine protected area. Despite the government willingness to conserve this important sector, the area still faces major threats. The increased interest in offshore oil development, recreation and artisanal fisheries in the northern sector of the gulf, and its status as a primary fishing ground for the area’s growing commercial trawl fisheries, represent critical threats to the area’s seabird populations. Seabird populations may be both negatively and positively affected by fishery activities. Many seabirds make intensive use of fishery discards, and it has been argued that their use has contributed to the expansion of several seabird populations. However, seabird attraction to fishing vessels to make use of waste has led in many cases to an increase in mortality resulting from drowning in fishing gear. Finally, seabirds may be negatively affected through resource extraction and habitat disturbance. Knowledge on the different interactions between trawl fisheries and seabirds is fundamental to understand how human dominated coastal ecosystems function and for the design of appropriate mitigation guidelines aimed at the long-term conservation of seabird populations. Our goals for this year are to (a) assess the potential overlap in resource use between the Magellanic Penguin and trawl fisheries, (b) complete the evaluation on the trophic relationship and food partitioning among inshore cormorants, (c) continue with the study of the contribution of fishery waste on the ecology and demography of expanding Kelp Gull populations, and (d) provide technical advice to government authorities, contributing to the development of Park’s Management Plan.

Conservation of the threatened Olrog’s Gull & associated seabirds of Bahía San Blas

"The Bahía San Blas project is currently requesting donations to buy field equipment, and to help financing their field work and educational program. Your contribution, regardless of the money amount granted, will make it possible for the team to continue their conservation work."

The Bahía San Blas Multiple Use Protected Area is located in southern Buenos Aires Province. This 4,000 km2 protected area includes estuarine areas with low islands, extensive intertidal mudflats and sandflats with drainage channels, salt marshes, crab beds, and open marine habitats. It is the breeding or migrating ground for several species of marine mammals, shorebirds, seabirds and marine turtles — some of which are globally threatened (i.e. Olrog’s Gull, Green Turtle, and Franciscana Dolphin). It is the breeding or migrating ground for several species of marine mammals, shorebirds, seabirds and marine turtles — some of which are globally threatened (i.e. Olrog’s Gull, Green Turtle, and Franciscana Dolphin).

Olrog’s Gull

For a detailed list of requested items and how to contribute to this project.

Contact Trogon Tours

Growing economic activities that are posing a threat to wildlife in this area include artisanal and sport fishing, unregulated tourism, harvesting of intertidal invertebrates, and mariculture. Our research is focused on seabird colonies located in the southern sector of the protected area, one of the main breeding sites of the threatened Olrog’s Gul. The Olrog’s Gull is endemic to the Atlantic coast of Argentina, Uruguay and southern Brazil. It has a small global breeding population estimated to be at 4000-5000 pairs (BirdLife International 2011), with over 95% restricted to the southern coasts of Buenos Aires Province, Argentina. Because of its low population size, restricted distributional range, and conservation threats, Olrog’s Gull is one of the few globally threatened Larus species, and is internationally considered by IUCN and BirdLife International as Vulnerable. Olrog’s Gull is highly dependent on intertidal habitats and has a rather specialized feeding ecology during the breeding season, preying almost exclusively on crabs (Neohelice granulata, Cyrtograpsus altimanus and C. angulatus). This specialized behavior makes Olrog’s Gull more vulnerable to changes in selective pressures and to environmental modifications resulting from human activities. Knowledge of the species’ spatial and temporal foraging patterns, the role of food resources in determining these patterns, and the potential overlap and conflict between foraging individuals and human activities, is essential for the development of adequate conservation and management guidelines. Previous research has identified the nesting of other six species of gulls and terns, making this area the most diverse along the Argentine coast with respect to nesting Charadriiform seabirds. These include the Kelp and Brown-hooded gulls (Larus dominicanus and L. maculipennis, respectively) and the Cayenne, Royal, Gull-billed and Snowy-crowned terns (Thalasseus sandvicensis eurygnathus, T. maximus, Gelochelidon nilotica, and Sterna trudeaui, respectively). However, no information is available yet on the patterns of nesting distribution, population sizes, and breeding cycles on any of these six species, information which is fundamental for planning and protecting their populations. Our goals for this year are to (a) identify main foraging areas of breeding Olrog’s Gulls at the two colonies using high resolution GPS-loggers and evaluate how spatial use varies throughout the breeding cycle, (b) survey the coastal sector, islands and islets, to determine the distribution of colonies, estimate breeding numbers, and obtain basic information on gull and tern breeding biology to help design future studies, and (c) provide authorities with information, maps and recommendations, contributing to the development of spatial and temporal zoning schemes to minimize negative effects on these colonial birds.

About the Research Team

Besides Dr. Pablo Yorio, there are other five researchers working on these two projects nowadays. They are: Dr. Alejandro Gatto, Sr. Diego González Cevallos, Dr. Nicolás Suárez, Dr. Nora Lisnizer and Msc. Patricia Dell’Arciprete.

Pablo Yorio completed his Doctorate in Biological Sciences at the University of Buenos Aires. He has a research position at the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and is currently acting as Technical Coordinator for the Wildlife Conservation Society Argentina Program. He is also Professor of the Seabird Ecology course at the Universidad Nacional de la Patagonia. Since 1984 he has been working on the ecology and conservation of Patagonian seabirds, including penguins, gulls, terns and cormorants. Research topics have included distribution and abundance of breeding populations, breeding biology, habitat selection, feeding ecology, interactions with human activities and conservation strategies. He has written over one hundred scientific articles, book chapters, and technical reports on issues related to seabirds and the conservation of coastal and marine environments in Argentina. He has directed or is directing several Doctorate and undergraduate thesis. He has acted as consultant in topics related to coastal and marine conservation for several national and international organizations.

Olrog’s Gull
  • Yorio, P. and Boersma, P.D. 1992. The effects of human disturbance on Magellanic Penguin behavior and breeding success. Bird Conservation International 2: 161-173.
  • Yorio, P., Frere, E., Gandini, P. and Harris, G. (eds.). 1998. Atlas de la distribución reproductiva de aves marinas en el litoral Patagónico Argentino. Plan de Manejo Integrado de la Zona Costera Patagónica. Fundación Patagonia Natural y Wildlife Conservation Society. Instituto Salesiano de Artes Gráficas, Buenos Aires. 221 pp.
  • Yorio, P., Frere, E., Gandini, P. and Conway, W. 1999. Status and conservation of seabirds breeding in Argentina. Bird Conservation International 9: 299-314.
  • Yorio, P., Frere, E., Gandini, P. and Schiavini, A. 2001. Tourism and recreation at seabird breeding sites in Patagonia, Argentina: current concerns and future prospects. Bird Conservation International 11: 231-245.
  • Yorio, P., Quintana, F., Gatto, A., Lisnizer, N. and Suárez, N. 2004. Foraging patterns of breeding Olrog’s Gull at Golfo San Jorge, Argentina. Waterbirds 27: 193-199.
  • Yorio, P. 2009. Marine protected areas, spatial scales and governance: implications for the conservation of breeding seabirds. Conservation Letters 2:171-178.
  • Yorio, P., Quintana, F., Dell’Arciprete, P. and González Zevallos, D. 2010. Spatial overlap between foraging seabirds and trawl fisheries: implications for the effectiveness of a marine protected area at Golfo San Jorge, Argentina. Bird Conservation International 20: 320-334.