Linking predator and prey behaviour: contrasts between Antarctic fur seals and macaroni penguins at South Georgia

2009 ◽  
Vol 157 (1) ◽  
pp. 99-112 ◽  
Author(s):  
Claire M. Waluda ◽  
Martin A. Collins ◽  
Andrew D. Black ◽  
Iain J. Staniland ◽  
Philip N. Trathan
Keyword(s):  
South Georgia ◽  
Fur Seals ◽  
Antarctic Fur Seals

Dispersal of male and female Antarctic fur seals (Arctocephalus gazella)

1998 ◽  
Vol 55 (4) ◽  
pp. 845-852 ◽  
Author(s):  
I L Boyd ◽  
D J McCafferty ◽  
K Reid ◽  
R Taylor ◽  
T R Walker
Keyword(s):  
Arctocephalus Gazella ◽  
Adult Males ◽  
The South ◽  
Male And Female ◽  
Breeding Sites ◽  
South Georgia ◽  
Orkney Islands ◽  
Fur Seals ◽  
South Orkney Islands ◽  
Antarctic Fur Seals

This study examined the foraging locations of adult male and female Antarctic fur seals (Arctocephalus gazella) in the Scotia Sea during the postbreeding period. Satellite transmitters were used to track adult males and females and to obtain information about dive depths. Male fur seals migrated away from the breeding area during the postbreeding period whereas females remained close to the breeding grounds and foraged in the same area during two consecutive years. The most intensive foraging by females was associated with the edge of the continental shelf of South Georgia. Males dived deeper than females. Counts of males at South Georgia and at the South Orkney Islands support the result from satellite tracking data showing that males move from South Georgia to the South Orkney Islands at the end of the breeding season. Unlike males, females were limited in their foraging range by the necessity to return to feed dependent young, so breeding sites are likely to be located close to foraging areas that are optimal for females. Locations used for feeding by females were avoided by males, either because they were suboptimal for males or because foraging by females at South Georgia causes local depletion of food, and males, which have the option to forage further afield, can forage more successfully in regions where there are no females. Comparison with fisheries data also suggests that these fur seals are targeting the most abundant exploitable prey.

Pup production and distribution of breeding Antarctic fur seals (Arctocephalus gazella) at South Georgia

1993 ◽  
Vol 5 (1) ◽  
pp. 17-24 ◽  
Author(s):  
I. L. Boyd
Keyword(s):  
Initial Period ◽  
Population Expansion ◽  
Breeding Population ◽  
Arctocephalus Gazella ◽  
South Georgia ◽  
Long Term Study ◽  
Fur Seals ◽  
Production And Distribution ◽  
Breeding Grounds ◽  
Antarctic Fur Seals

A census of the breeding population of Antarctic fur seals (Arctocephalus gazella) at South Georgia was carried out during the 1990/91 breeding season. Using counts of adult females ashore at the breeding grounds during the pupping period, together with corrections for the likelihood of a female being ashore at a census and for pregnancy rate (71% in 1990/91), pup production was estimated as 269 000 (95% confidence intervals 188 000-350000). The breeding population in 1990/91 was reduced at long-term study sites probably because of limited food availability. Data from these sites were used to estimate the pup production of the population had 1990/91 been a typical year. Based on values from 1983/84 to 1990/91, pup production in 1990/91 would have been 378000 (se=19100) if it had been an average year. The annual increase in pup production from 1976/77 to 1990/91 has declined to 9.8% since the initial period of population expansion in the 1950s and 1960s. Increased population size has led to an expansion of the breeding range at South Georgia.

scholarly journals Entanglement of Antarctic fur seals at Bird Island, South Georgia

2013 ◽  
Vol 74 (1) ◽  
pp. 244-252 ◽  
Author(s):  
Claire M. Waluda ◽  
Iain J. Staniland
Keyword(s):  
South Georgia ◽  
Fur Seals ◽  
Antarctic Fur Seals

Age distribution of breeding female Antarctic fur seals in relation to changes in population growth rate

1990 ◽  
Vol 68 (10) ◽  
pp. 2209-2213 ◽  
Author(s):  
I. L. Boyd ◽  
N. J. Lunn ◽  
P. Rothery ◽  
J. P. Croxall
Keyword(s):  
Population Growth ◽  
Survival Rates ◽  
Age Distribution ◽  
Adult Survival ◽  
South Georgia ◽  
Breeding Female ◽  
Fur Seals ◽  
Rate Of Increase ◽  
The Mean ◽  
Antarctic Fur Seals

The age distribution of breeding female Antarctic fur seals at Bird Island, South Georgia, in 1988 was compared with the age distribution of a sample obtained in 1971–1973. The mean age in 1971–1973 was 7.41 (SE = 0.26) years and in 1988 it was 6.93 (SE = 0.20) years. After correction for age-dependent arrival time at the pupping beach in 1988, the mean age was 6.22 (SE = 0.14 years), which was significantly lower than in 1971–1973. Indicators of population size suggested that population growth at Bird Island had declined to below 3% annually by 1988 compared with rapid growth (17%) in 1958–1972. Exponential models fitted to the frequency distribution of age-classes greater than age 5 years and corrected for the rate of increase of the population gave adult survival rates of 0.66 (SE = 0.03) and 0.88 (SE = 0.02) for the 1988 and 1971–1973 samples, respectively. The reduced apparent adult survival rate in the 1988 sample was probably caused by emigration brought about by high densities of females on the pupping beaches. There are few signs from this analysis that the fur seal population at South Georgia is close to carrying capacity.

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