Aves acuáticas de laguna Cáhuil, región de O'higgins, Chile central

Los humedales costeros del centro de Chile son sitios ecológicamente relevantes para las aves, pero en las lagunas de la región de O'Higgins, se sabe poco sobre los ensambles de aves acuáticas. Durante 2015 evalué la riqueza y cantidad de aves acuáticas en la laguna Cáhuil, centro de Chile. Realicé conteos mensuales (un día al mes) de cuatro transectos de línea fija (200 m) establecidos a lo largo de la playa. Se contaron todas las aves presentes en la orilla de la playa, la superficie del agua y los bancos de arena. Detecté 28 especies de aves, siendo Cygnus melancoryphus, Fulica armillata y Larus dominicanus las más numerosas. Se discute la importancia de realizar muestreos sistemáticos para tener una comprensión más completa de los conjuntos de aves acuáticas en toda la región y para desarrollar acciones de conservación.

ISOLATION OF BACTERIA FROM THE SITES OF FEED AND NESTING ACTIVITY OF LARUS DOMINICANUS (GALINDEZISLAND, THE MARITIMEANTARCTIC) AND THEIR CHARACTERISTICS

The aim of the study was to investigate the number of different groups of microorganisms in soil samples from sites of feed and nesting activity of Larus dominicanus (Galindez Island, the maritime Antarctic) and to characterize the physiological and biochemical properties of isolated microorganisms. Methods. In the work standard microbiological and biochemical research methods were used (cultural, microscopy methods, determination of enzymatic activity). Genomic DNA was isolated by soft lysis. The 16 S rRNA gene was amplified using universal primers 27F and 1492R. Identification of isolates was performed based on the determination of the 16 S rRNA gene sequence, physiological and biochemical properties. Results. The number of microorganisms of different groups in soil samples from sites of food and nesting activity of Larus dominicanus (Galindez Island, the maritime Antarctic) was established. 74 isolates of bacteria were isolated. Isolate 2U-K-37, that was isolated from upper layer of soil, and isolate 2B-K-54, that was isolated from a depth of 2–5 cm, were characterized by amylase, lipase, phospholipase, protease activities, the ability to form exopolysaccharides.They were identified by sequencing of the 16 S rRNA gene, physiological and biochemical properties as Pedobacter sp. 2U-K-37 and Pseudarthrobacter sp. 2B-K-54. In the soil samples from sites of feed and nesting activity of Larus dominicanus microorganisms that metabolize nitrogen of organic compounds were the most numerous. Oligotrophic microorganisms and microorganisms that metabolize nitrogen of inorganic compounds were less numerous. The number of microorganisms of groups in the samples from the soil surface and lower layers differed statistically significant. Isolated and identified obligate psychrophilic strain Pedobacter sp. 2U-K-37 and psychrotolerant strain Pseudarthrobacter sp. 2B-K-54 are moderate halophiles that are able to hydrolyze starch, gelatin, tween-20 and synthesize exopolysaccharides.

Population Studies on the Southern Black-Backed Gull

<p>An account is given of ecological studies on the Southern Black-backed Gull Larus dominicanus Licht in which attention is directed to the structure and balance of the Wellington population. This population is large; in the 1963-64 season more than 5,600 pairs were breeding in the study area, and the peak non-breeding season population in 1964 exceeded 12,000 birds. Its growth has been closely associated with the increase of the human population, and the present distribution and dispersal of gulls is strongly influenced by the distribution of " artificial" feeding sites such as refuse tips and meatworks. The population is composed of breeding colonies, night roosting flocks and daily communal flocks which are inter-related by the social activities and dispersal of the birds. Thus the population is more or less integrated, rather than simply comprising discrete geographic units. Seasonal fluctuations in size and age composition of communal flocks are discussed. Breeding success varies between colonies. It is affected by mammalian predation in some, and by drowning in others, while the largest colonies are comparatively safe for breeding birds. The rapid growth of the whole population in the last five to 10 years appears to have some influence on nesting density, clutch size, spread of laying and overall breeding success. In recent years production of young has been twice that required to maintain the population which has grown at the rate of not less than 7.2% annually. Mortality of banded gulls inside and outside the colony is described and the influence of several factors on chick mortality examined. The principal factor limiting the population appears to be the food supply in relation to the number of birds. When numbers increase and the food supply diminishes, major regulation of the population is apparently achieved in the colony by predation (but not cannibalism) of young by adults. Dispersal of banded gulls from the Wellington colonies is very restricted.</p>

Population Studies on the Southern Black-Backed Gull

<p>An account is given of ecological studies on the Southern Black-backed Gull Larus dominicanus Licht in which attention is directed to the structure and balance of the Wellington population. This population is large; in the 1963-64 season more than 5,600 pairs were breeding in the study area, and the peak non-breeding season population in 1964 exceeded 12,000 birds. Its growth has been closely associated with the increase of the human population, and the present distribution and dispersal of gulls is strongly influenced by the distribution of " artificial" feeding sites such as refuse tips and meatworks. The population is composed of breeding colonies, night roosting flocks and daily communal flocks which are inter-related by the social activities and dispersal of the birds. Thus the population is more or less integrated, rather than simply comprising discrete geographic units. Seasonal fluctuations in size and age composition of communal flocks are discussed. Breeding success varies between colonies. It is affected by mammalian predation in some, and by drowning in others, while the largest colonies are comparatively safe for breeding birds. The rapid growth of the whole population in the last five to 10 years appears to have some influence on nesting density, clutch size, spread of laying and overall breeding success. In recent years production of young has been twice that required to maintain the population which has grown at the rate of not less than 7.2% annually. Mortality of banded gulls inside and outside the colony is described and the influence of several factors on chick mortality examined. The principal factor limiting the population appears to be the food supply in relation to the number of birds. When numbers increase and the food supply diminishes, major regulation of the population is apparently achieved in the colony by predation (but not cannibalism) of young by adults. Dispersal of banded gulls from the Wellington colonies is very restricted.</p>

Nidificación del gaviotín sudamericano (Sterna hirundinacea) en islas Caicura (41° S), Seno de Reloncaví, sur de Chile

El gaviotín sudamericano (Sterna hirundinacea) es un ave marina endémica de las costas de América del Sur. El presente trabajo describe su nidificación en islas Caicura (41° S), sur de Chile, entregando información sobre el número de nidos, huevos y polluelos, durante tres temporadas reproductivas consecutivas (2013-14, 2014-15, 2015-16). La puesta de huevos comenzó en noviembre, observándose polluelos en diciembre, y volantones en enero. La mayoría de los nidos contó con sólo un huevo. El total de huevos por temporada fue de 295, 386 y 313, respectivamente. La tasa de eclosión fue significativamente distinta entre las tres temporadas, aumentando en el tiempo desde un 41,2%, 62,5% y 82,8%, respectivamente. El total acumulado de polluelos por temporada fue de 119, 249 y 223, respectivamente. Se estimó una mortalidad total de polluelos cercana al 10%. Se identificó a la gaviota dominicana (Larus dominicanus) como el principal depredador de huevos y polluelos del gaviotín sudamericano. Finalmente, las islas Caicura son el segundo sitio de mayor importancia en Chile, para la reproducción del gaviotín sudamericano.

Molecular Characterization of New Haplotype of Genus Sarcocystis in Seabirds from Magdalena Island, Southern Chile

Evidence of sarcocystid infection was investigated in samples of 16 penguins (Spheniscus. magellanicus), four Dominican gulls (Larus dominicanus) and two Chilean skuas (Stercorarius chilensis) found in Madalenas Islands, Chile, in 2017. Samples of skeletal muscle, cardiac muscle and brain from all birds were screened by a pan-sarcocystid nested-PCR targeting a short fragment of the gene encoding the small ribosomal unit (nPCR-18Sa). The only two positive samples by nPCR-18Sa, both from skuas, were tested by a nested-PCR directed to the internal transcribed spacer 1 (nPCR-ITS1), also a pan-sarcocystidae nested-PCR, and to a nested-PCR directed to the B1 gene (nPCR-B1), for the exclusive detection of Toxoplasma gondii. The two nPCR-18Sa-positive samples were nPCR-ITS1-positive and nPCR-B1-negative. The nPCR-ITS1 nucleotide sequences from the two skuas, which were identical to each other, were revealed closely related to homologous sequences of Sarcocystis halieti, species found in seabirds of northern hemisphere. Larger fragments of genes encoding 18S and partial sequences of genes coding for cytochrome oxidase subunit 1 were also analyzed, corroborating ITS1 data. The haplotypes found in the skuas are unprecedent and closely related to species that use birds as the definitive host. Further studies need to be carried out to detect, identify and isolate this parasite to understand the epidemiology of the infection and its impact on the health of marine fauna.