Red-legged Cormorant Research Articles

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 fa...

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

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 and conservation of seabirds breeding in Argentina

SummaryWe present information on the current population status of seabirds that breed along the Patagonian coast obtained between 1993 and 1995. A total of 16 species, including two penguins, one petrel, five cormorants, three gulls, three terns and two skuas, breed along the 3,400-km coast from southern Buenos Aires (38°58'S) to Tierra del Fuego (54°50'S). Breeding seabirds are not as abundant in coastal Argentina as was previously thought. Eleven of the 16 species have less than 5,000 pairs. The most abundant seabird is the Magellanic PenguinSpheniscus magellanicuswith 964,000 pairs, an order of magnitude higher than all other species. As well as Magellanic Penguins, Kelp GullsLarus dominicanus, and Imperial CormorantsPhalacrocorax atricepsare relatively abundant and have a wide distribution. Other seabirds, such as Red-legged Cormorants P.gaimardi, Olrog's GullsL. atlanticus, and Dolphin Gulls L.scoresbii, have a highly restricted distribution or nest in small colonies at a few sites in Argentina. The Patagonian coast is one of the most pristine coastal ecosystems in the world and, thus far, few seabirds are seriously threatened. However, oil pollution and commercial fisheries are having a negative impact on some seabirds and some colonies have shown recent declines. Current threats and impacts, including pollution, fisheries, human disturbance, guano harvesting, and introduction of alien species are discussed. There are currently 34 protected coastal areas, although in many cases protection measures are not adequately enforced and some areas with high seabird diversity and abundance still lack legal and effective protection. Conservation actions and requirements, including direct actions, monitoring and research are suggested.

New records of feather lice from some seabirds in Chile.

Six species of chewing lice (Phthiraptera: Menoponidae, Philopteridae) are reported from four species of seabirds collected off the coast of Chile. They are Eidmanniella pellucida, Piagetiella transitans, and Piagetiella caputincisa, from a Guanay cormorant (Phalacrocorax bougainvillii); Harrisoniella ferox collected from a black-browed albatross (Diomedea melanophrys); Ancistrona vagelli from a white-necked petrel (Pterodroma externa); and Pelmatocerandra flinti collected from a Magellan diving petrel (Pelecanoides magellani). Eidmanniella pellucida and P. transitans are reported from Chile for the first time. Piagetiella caputincisa from the Guanay cormorant may be a contaminant from a red-legged shag (Phalacrocorax gaimardi).

Ornithodoros (Alectorobius) amblus (Acarina: Ixodoidea: Argasidae): Identity, Marine Bird and Human Hosts, Virus Infections, and Distribution in Peru

Ornithodoros (Alectorobius) amblus Chamberlin 1920, adults previously were described inadequately. Practically nothing was known regarding the identity, hosts, distribution, and biology of this species. We redescribe both sexes, describe the nymph and larva, and present criteria for differentiating these stages from those of other members of the O. (A.) capensis group in the Western Hemisphere. Samples were collected from 13 localities on the Pacific coast and on offshore islands of Peru. Hosts recorded are the Peruvian Brown Pelican, Peruvian Booby, Blue-footed Booby, Red-legged Cormorant, Guanay Cormorant, and Inca Tern. These birds are not long-distance migrants and more widely distributed species of the O. (A.) capensis group have not been found parasitizing them. The life cycle is characteristic of the O. (A.) capensis group; the first nymphal instar does or does not feed. Humans are attacked eagerly by O. (A.) amblus and suffer afterward from severe inflammation and "incredible" pruritus, and possibly from more severe illness. Viruses infecting this tick are Punta Salinas (Hughes serogroup, family unclassified) and Huacho (Reoviridae, genus Orbivirus, Kemerovo serogroup). Dense tick populations cause breeding birds to desert numerous nests; thus, O. (A.) amblus is economically important to the Peruvian guano industry. Certain spiders and lizards may prey on this tick.