Browsing by Author "Gajardo, Marko"
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Item Notas sobre Bubulcus ibis y Eudyptes chrysolophus de las islas Shetland del Sur(1986) Torres, Daniel; Gajardo, Marko; Valencia, JoséSe informa de dos nuevos hallazgos de Bubulcus ibis en isla Greenwich, Shetland del Sur, en 1984 y 1985. Estos se agregan al primer registro realizado en 1979. Estas observaciones tienden a confirmar la hipótesis de aumentos poblacionales de la especie en la región de Magallanes, que es la mas cercana a las islas Shetland del Sur. Para Eudyptes chrysolophus se agregan nuevos registros: Una pareja en cabo Shirreff, isla Livingston, en cuatro oportunidades, y tres animales solitarios en isla Rey Jorge, dos de ellos en isla Ardley. En ninguno de estos casos se observó intentos de nidificación. Se discuten algunos factores ecológicos que pueden estar favoreciendo la dispersión de estas especies en la Antártica marítima.Item Numerical changes in the population of the Antarctic fur seal Arctocephalus gazella at two localities of the South Shetland Islands(1987) Oliva, Doris; Durán, René; Gajardo, Marko; Torres, DanielThe Antarctic fur seal Arctocephalus gazella was intensively exploited during the 19th century in its distribution area. The ceasing of its exploitation, subsequent international protection, and the availability of food, mainly krill, due to the decreasing of whale production, brought about the recovery of the Antarctic fur seal specially in South Georgia, which became the "dispersing centre" of these animals to recolonize their earlier breeding areas, the Scotia Arc and Subantarctic Islands. Since the breeding season 1981-82 until that of 1984-85, population census have been carried out including the pup tagging at Stigant Point (62º02' S, 58º45' W), King George Island, as well as at Cape Shirreff (62º27' S, 60'47' W), Livingston Island, South Shetland Islands. The population growth in colonies with low density should fit an exponential model. The total population should increase and also the proportion of females, subadult males and pups. The population growth curve at Cape Shirreff fits an exponential model. The population structure is significantly different between Cape Shirreff and Stigant Poin in 1983-84 and 1984-85. The population growth in Cape Shirreff between 1983-84 and 1984-85 is 64%, the most part of which is explained by immigration. Results show a rapid population growth, a low neonatal mortality and a higher proportion of males at Cape Shirreff.