Trafico de mejueres

R.P. Wilson · B. Alvarrez · L.Latorre · D. Adelung
B. Culik · R. Bannasch
The movements of gentoo penguins Pygoscelis papua
from Ardley Island, Antarctica
Received: 1 October 1997 /Accepted: 3 February 1998
Abstract The movements of gentoo penguins (Pygoscelis papua) in Antarctica were studied by equipping a total of 37 birds captured at Ardley Island, South Shetlands between December1991 and May 1996 with position-determining devices. Information on area usage was derived from 20 of' these devices and covered the incubation period (N = 3 birds), the chick-rearing period (N = 14 birds) and the over-wintering period (N = 3 birds). During incubation birds only ventured further than 50 km from the colony 20% of the time and no individual ranged further than 200 km from thecolony. In contrast, no individuals attending chicks ranged further than 16 km from the colony. During winter the maximum distance ranged from the colony was 268 km. Mean distances between the birds and the colony were 80, 81 and 127 km. Individual birds tended to associate with one spot, making short (10 day) forays away before returning to nodal areas. The ranging capacity of gentoo penguinsappears considerably less than that of sympatric congeners and may reflect the ability of gentoo penguins to dive deeper and thus exploit prey not accessible to congeners. IntroductionThe extent to which seabirds can exploit various areas of the marine environment is dependent on a number of constraints necessitate parents to repeatedly associate with the nest site to incubate the eggs or to feedyoung. Two primary determinants of the marine areas birds can potentially exploit are the length of time that birds can be absent from the breeding site and their travelling speed (e.g. Williams and Siegfried 1980) Although penguins are the most aquatic of all birds, they are particularly restricted in the areas they can exploit compared to volant species because the only travel slowly (Costa 1991;Wilson 1995). Penguins can be broadly divided into two groups depending on their capacity for movement. Some species, such as the macaroni penguin Eudyptes chrysolophus, are migratory during the non-breeding season, while others, such as the African penguin Spheniscus demersus, are considered sedentary (Croxall and Davis, in press). Migratory species have a tendency to forage further of shorethan sedentary species during the breeding season (Croxall and Davis, in press) and by so doing reduce inter-specific competition for prey with species foraging inshore (e.g. Cooper et al. 1990; Hindell et al. 1995 ). Why gentoo penguins (Pvgoscelis papua) are generally thought to be sedentary during the non-breeding season (for summary see Williams 1995) while congeneric Adélie (Pygoscelisadéliae) and chinstrap (Pygoscelis antarctica) penguins are migratory is unclear (Davis et al.. 1996; Wilson et. al. 1998), as is why, even during the breeding season, gentoo penguins forage much closer inshore than either congener (cf. Lishman 1985; Trivelpiece et al. 1987; Wilson 1995). In areas of breeding simpatry the diets of the three species are very similar (Trivelpiece et al. 1987 andreferences therein). Despite the general conclusion that gentoo penguins are sedentary for the whole year, the published data considering the movements of these birds are equivocal (see Bost and Jouventin 1990 and references therein) because, to our knowledge, no study has documented in detail distribution at sea in birds from known breeding sites (as has been done, for example, in Adélie penguinsLa pensión de vejez por deficiencia en la legislación
colombiana: restricciones de acceso desde su
instrumento evaluador
*The old age pension based in deficiency in Colombian legislation and the restrictions to access to it due to its assessment tool Natalia E. Gómez R1; Sandra P. Duque Q2; Patricia González S
3.1 Abogada Especialista en derecho de la seguridad social, coordinadora del...