Esteban Frere

Tourism and recreation at seabird breeding sites in Patagonia, Argentina: current concerns and future prospects

Summary Seabird colonies often constitute valuable tourist attractions. Different species differ in their sensitivity to human disturbance and, although birds may habituate to visitors, inappropriate intrusions at poorly managed sites may result in adverse effects on breeding individuals. The rapid growth of wildlife-based tourism and recreation in coastal Patagonia, Argentina, presents opportunities for significant economic benefits but also raises concerns about the potential effects on seabird colonies. Sixteen seabird species breed along the Patagonian coast, with Magellanic Penguin Spheniscus magellanicus being one of the main tourist attractions. At least 27 sites where seabirds breed are currently visited by people either through organized tourism or for recreational purposes, 19 of which are included in coastal protected areas. The number of visitors per year varies from 50 to more than 100,000, depending on the site. Negative effects on seabird reproduction in Patagonia are through direct destruction of nests or their contents and desertion of offspring, particularly at locations where seabirds nest in association with or near to colonies of avian predators. Tourism and recreation activities are growing in extent and intensity at most coastal sectors in Patagonia. Current trends in coastal recreation activities may result in negative effects on breeding seabirds unless management guidelines are developed and enforced. Information shows that tourism in coastal Patagonia is compatible with seabird conservation if appropriately managed. Given the rapid increase in the interest in visiting seabird colonies in Patagonia, several management tools such as sanctuaries, the limitation of visitor numbers and both temporal and spatial zoning, need to be implemented in the short term.

Interaction between Magellanic Penguins and Shrimp Fisheries in Patagonia, Argentina

We analyzed the effect of the shrimp fishery on Magellanic Penguins (Spheniscus magellanicus) in two ways: (1) we determined whether penguins were incidentally killed and the magnitude of incidental take, and (2) estimated the overlap between penguin diet and fish by-catch of the shrimp fishery (total capture excluding shrimp and seabirds). We worked with the fishing fleet operating at Golfo San Jorge with onboard observers over 200 days in 1995-1997, sampling fishery by-catch and entangled birds. Penguins were affected during the austral summer. Estimations of mortality rates showed 0.33% of the breeding population at Golfo San Jorge is incidentally killed by the shrimp fishery every summer. By-catch in shrimp fishery nets was composed of species important as penguin prey (anchovy and hake) in higher proportions during summer. The daily by-catch of these species was higher than the total calculated daily intake for all penguins breeding in the Golfo San Jorge. This could have a significant effect on birds. We recommend that an observer program be implemented to monitor seabird mortality and that fishing gear should be improved to reduce the indirect effect of the fish by-catch on penguins.

Status and conservation of Magellanic Penguins Spheniscus magellanicus in Patagonia, Argentina

There are 36 breeding colonies of Magellanic Penguins Spheniscus magellanicus along the coast of mainland Argentina. During the breeding period we counted the number of active nests and estimated the breeding population was approximately 652,000 pairs. Development of coastal areas is diminishing the quality of Magellanic Penguin breeding habitat and reducing penguin reproductive success. Adult mortality rates are increasing because of human activities. Maritime petroleum traffic and petroleum operations are known to cause mortality. Fishing activities cause incidental mortality and may negatively affect penguin foraging and reproductive success. In some areas, offal is increasing gull populations with a corresponding increase in predation on penguin eggs and chicks, thereby lowering reproductive success. These sources of mortality are relatively recent and are human caused. We found three areas where human activities are of particular concern: Peninsula Valdes, Golfo San Jorge and Estrecho de Magallanes. Human impacts on Magellanic Penguin populations could be reduced, benefiting the tourist industry where yearly tens of thousands of people come to the provinces of Chubut and Santa Cruz to visit penguin colonies. Existen 36 colonias de pinguino de Magallanes Spheniscus magellanicus a lo largo de la costa Argentina. La poblacion reproductiva se estimo en 652,000 parejas realizando un conteo de nidos activos durante la estacion reproductiva. El desarrollo de las areas costeras esta reduciendo la calidad del habitat de reproduccion y el exito reproductivo del pinguino de Magallanes. El trafico de petroleo y las actividades relacionadas son conocidas causas de mortalidad. Las actividades pesqueras estan causando mortalidad incidental y pueden estar afectando negativamente el exito de alimentation y reproductivo. En algunas areas la basura esta contribuyendo al aumento de la poblacion de gaviotas, incrementandose la predacion sobre huevos y pichones de pinguino reduciendo su exito reproductivo. Estas fuentes de mortalidad son relativamente recientes y provocadas por el hombre. Hemos detectado tres areas donde la mortalidad relacionada con actividades humanas es preocupante: Peninsula Valdes, Golfo San Jorge y Estrecho de Magallanes. El impacto humano sobre la poblacion de pinguino de Magallanes podria reducirse y beneficiar la industria turistica de las provincias de Chubut y Santa Cruz, donde anualmente decenas de miles de personas visitan las colonias reproductivas del pinguino.

Sex determination of adult Rock Shags by molecular sexing and morphometric parameters

Abstract Male and female Rock Shags (Phalacrocorax magellanicus) are not obviously sexually dimorphic in plumage or size and are thus difficult to distinguish in the field. We evaluated the utility of two different DNA-based techniques for sexing adult Rock Shags. We found that the primer set 2550F/2718R (originally tested in three individuals of P. carbo), with minor differences in the forward primer, provided a consistent and simple sexing method for Rock Shags. Moreover, we obtained three reliable discriminant functions for sexing adults from three different colony sites between 42° to 47°S in coastal Patagonia, Argentina. Discriminant analysis of five external characters of adult birds indicated that head, bill, and wing lengths were the most accurate variables for use in a discriminant function model, predicting the sex of 80–86% of the birds. Males were significantly larger than females for all body measurements except for bill depth. Rock Shags showed less marked sexual dimorphism than other phalacrocoraciid species.

N-dimensional animal energetic niches clarify behavioural options in a variable marine environment

SUMMARY Animals respond to environmental variation by exhibiting a number of different behaviours and/or rates of activity, which result in corresponding variation in energy expenditure. Successful animals generally maximize efficiency or rate of energy gain through foraging. Quantification of all features that modulate energy expenditure can theoretically be modelled as an animal energetic niche or power envelope; with total power being represented by the vertical axis and n-dimensional horizontal axes representing extents of processes that affect energy expenditure. Such an energetic niche could be used to assess the energetic consequences of animals adopting particular behaviours under various environmental conditions. This value of this approach was tested by constructing a simple mechanistic energetics model based on data collected from recording devices deployed on 41 free-living Magellanic penguins (Spheniscus magellanicus), foraging from four different colonies in Argentina and consequently catching four different types of prey. Energy expenditure was calculated as a function of total distance swum underwater (horizontal axis 1) and maximum depth reached (horizontal axis 2). The resultant power envelope was invariant, irrespective of colony location, but penguins from the different colonies tended to use different areas of the envelope. The different colony solutions appeared to represent particular behavioural options for exploiting the available prey and demonstrate how penguins respond to environmental circumstance (prey distribution), the energetic consequences that this has for them, and how this affects the balance of energy acquisition through foraging and expenditure strategy.

Feeding Performance and Foraging Area of the Red-Legged Cormorant

Abstract The foraging behavior and feeding locations of the Red-legged Cormorant (Phalacrocorax gaimardi) were studied at Ria Deseado, Argentina during the last week of the incubation period in 1999. VHF radio-transmitters were deployed on six nesting adult cormorants. Red-legged Cormorants fed during the daylight hours and made 4.0 ± 0.8 trips per day, with a mean duration of 1.2 ± 0.8 h. Birds spent 27% of daylight hours away from the colony on feeding trips, diving for 96% of the foraging trip, and made a mean of 78 dives per trip. Mean foraging range was 1.9 ± 0.9 km, being the shortest of any of the Patagonian cormorant species. Red-legged Cormorants fed mainly in shallow waters <5 m deep and within one km from the shore. Most of the feeding trips were undertaken during falling tide, when the birds performed the shortest feeding trips with maximum diving rates and, probably minimized transit times and maximized searching time on the seafloor. Our results show that foraging behavior is mainly influenced by environmental factors such as the direction of the tide. Red-legged Cormorants seems able to forage by selecting the appropriated tidal conditions to minimize foraging effort.

Predicting the Sex of Kelp Gulls by External Measurements

-Male and female 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 length, bill length and bill depth were the most accurate variables for use in a discriminant function model, predicting sex with 97% accuracy. Received 12 May 2000, accepted 1June 2000.

DIVING BEHAVIOR OF THE RED-LEGGED CORMORANT IN SOUTHEASTERN PATAGONIA, ARGENTINA

Abstract We studied the diving behavior of Red-legged Cormorants (Phalacrocorax gaimardi) in Patagonia, Argentina, using VHF radio-transmitters deployed during incubation. Red-legged Cormorants made foraging trips in inshore waters less than 15 m deep. Mean dive duration was 26.8 ± 2.0 sec while mean time at surface was 9.2 ± 0.9 sec (n = 2217 dives). The birds spent 74% of their foraging time underwater. Diving efficiency was different among individuals, and was among the highest reported for the Phalacrocoracidae. Dive variables were correlated with the height of the tide, suggesting that the birds forage on the seabed. Red-legged Cormorants were efficient divers, investing most of their feeding time underwater and foraging in shallow waters, maximizing bottom time. Our results are consistent with the hypothesis that Red-legged Cormorant diving behavior is strongly influenced by a combination of environmental variables (bottom heterogeneity and high tide width) characteristic of the south coast of Patagonia. Comportamiento de Buceo del Phalacrocorax gaimardi en la Patagonia Sudoriental, Argentina Resumen. Se estudió el comportamiento de buceo del Phalacrocorax gaimardi en Patagonia, Argentina, usando transmisores VHF instalados durante el periodo de la incubación. P. gaimardi realizó sus viajes de alimentación en áreas costeras poco profundas (<15 m). La duración media del buceo fue 26.8 ± 2.0 seg y el tiempo medio en superficie de 9.2 ± 0.9 seg (n = 2217). Las aves pasaron bajo el agua un 74% de su tiempo de alimentación, mostrando una de las eficiencias de buceo más altas mencionadas para los Phalacrocoracidae. Los parámetros de buceo se correlacionaron con la altura de la marea, sugiriendo que las aves se alimentaron en el fondo marino. Los individuos de P. gaimardi fueron eficientes buceadores, invirtiendo la mayoría de su tiempo de alimentación debajo del agua en aguas someras, maximizando el tiempo en el fondo marino. Nuestros resultados apoyan la hipótesis que P. gaimardi tiene un comportamiento de buceo que responde a las características ambientales de la costa sur de la Patagonia (heterogeneidad del fondo marino y grandes amplitudes de marea).

Status of the Red-legged Cormorant in Peru: What Factors Affect Distribution and Numbers?

Abstract The distribution and abundance of Red-legged Cormorants (Phalacrocorax gaimardi) were assessed by visiting 42 localities on the mainland and surveying most of the islands along Peru’s 2,500 km coastline between October 1999 and December 2000. Cormorants were distributed in small discrete groups (Mode = 5 birds, range 1-69) from Isla Foca (5°12’S) to Morro Sama (18°0’S). The southern (56% of the total numbers) and central (34%) coast held a larger proportion of cormorants than did the northern region (10%). Birds were mainly located in unprotected areas, either on islands (6%) or on the mainland (51%). The remainder was found in protected areas, either guano bird islands (27%), guano bird headlands (3%) or within the Paracas Reserve (13%). We counted 658 birds (95% adults, 5% juveniles), but based on bird density, availability of suitable habitats and cliff lengths we predicted a total of 1,803 ± 282 birds in Peru. Red-legged Cormorants built their nests on narrow ledges on vertical rocky walls falling sheer to the sea, located, on average, 17.8 m (range = 3-50, N = 56) above the sea level on open cliffs, high-up in sea cave entrances or on small islets. They have undergone a spectacular decline over the last 30 years. Between 1968 and 1999-2000, the numbers at ten localities in the northern and central coast decreased from 3,229 to 69 birds. It is likely that low numbers recorded in this study reflect the devastating effects of the strong El Niño Southern Oscillation (ENSO) of 1997-98, as numbers prior and after this event at eight southern localities decreased by 73%. Because of the inaccessibility of their nesting and roosting sites and the lack of natural predators, Red-legged Cormorants are apparently not in danger at such sites. However, entanglement in fishing nets, competition for food in inshore waters, pollution, human disturbance and harvesting of kelp banks are potential threats at sea and could affect the population recovery.

Flexible foraging for finding fish: variable diving patterns in Magellanic penguins Spheniscus magellanicus from different colonies

AbstractSeabirds have to deal with environmental variability and are predicted to modulate foraging behavior to maximize fitness, with particularly strong selection pressure for optimal behavior during chick provisioning when energy demands are high. We reported data from 42 breeding birds equipped during the early chick-rearing period with depth recorders at four different colonies [Punta Norte (42°S), Bahía Bustamante (45°S), Puerto Deseado (47°S) and Puerto San Julián (49°S)] in patagonian Argentina. Although Magellanic penguins are purported to show little flexibility in foraging behavior, we discovered marked inter-colony differences in diving behavior. Even though the southern marine ecosystems, in general, and the area exploited by Magellanic penguins from the studied colonies, in particular, are usually characterized by their stability, we cannot entirely exclude that interannual differences may have also affected our results. The colonies located in the center of the breeding distribution, Bahía Bustamante and Puerto Deseado, showed the greatest diving and foraging effort with Bahía Bustamante penguins having the deepest and longest dives of all birds and requiring the longest post-dive recovery durations at the surface. Puerto Deseado had the birds with the highest values of diving effort parameters. Penguins from both colonies also had the highest descent and ascent rates during dives. We assume that the clear variation in diving behavior reflects the response of the birds to the varying prey types and availability around the different colonies, but note that, despite this, some colonies fare markedly better than others in breeding.ZusammenfassungFlexible Suche nach Fisch: unterschiedliche Tauchmuster von Magellan -PinguinenSpheniscus magellanicusaus verschiedenen Kolonien Seevögel müssen Umweltveränderungen bewältigen und können vermutlich ihre Nahrungssuche anpassen, um ihre Fitness zu maximieren, vor allem bei starkem Selektionsdruck für optimales Verhalten während der Jungenaufzucht, wenn der Energiebedarf besonders hoch ist. In vier verschiedenen Kolonien [Punta Norte (42°S), Bahía Bustamante (45°S), Puerto Deseado (47°S) and Puerto San Julián (49°S)] im argentinischen Teil Patagoniens wurden während der frühen Kükenaufzuchtsphase 42 Brutvögel mit Tiefenmessern ausgerüstet. Obwohl Magellan-Pinguine angeblich eine geringe Flexibilität im Nahrungssuchverhalten zeigen, konnten deutliche Unterschiede im Tauchverhalten zwischen den Kolonien festgestellt werden. Wenngleich die südlichen marinen Ökosysteme im Allgemeinen, und das von den untersuchten Magellan-Pinguinen genutzte Gebiet im Speziellen, normalerweise durch ihre Stabilität gekennzeichnet sind, kann nicht gänzlich ausgeschlossen werden, dass Unterschiede zwischen den Jahren die Ergebnisse beeinflusst haben könnten. Die Kolonien, die in der Mitte des Brutverbreitungsgebietes liegen, Bahía Bustamante und Puerto Deseado, zeigten den größten Aufwand für Tauchen und Nahrungssuche. Die Bahía Bustamante Pinguine tauchten von allen Vögeln am tiefsten und am längsten und benötigten die längsten Erholungsphasen an der Wasseroberfläche nach ihren Tauchgängen. Puerto Deseado Pinguine zeigten die höchsten Werte im Tauchaufwand. Vögel aus beiden Kolonien hatten die höchsten Ab- und Auftauchgeschwindigkeiten während der Tauchgänge. Wir nehmen an, dass die Unterschiede im Tauchverhalten die Antwort der Vögel auf variierende Beutetypen und deren Verfügbarkeit um die verschiedenen Kolonien reflektiert. Ungeachtet dessen ist aber darauf hinzuweisen, dass das Brutgeschäft in einigen Kolonien deutlich besser läuft als in anderen.