Australian fur seals establish haulout sites and a breeding colony in South Australia (original) (raw)
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Wildlife Research, 1996
The South Neptune Island group is a well-known site for the New Zealand fur seal, Arctocephalus forsteri. A survey of seals in South Australia and Western Australia in the 1989-90 summer indicated that colonies on the South Neptunes and the adjacent North Neptunes group contained half of the breeding population in Australia. The abundance of pups at the South Neptune group was determined in four breeding seasons: 1969-70, 1988-89, 1989-90 and 1992-93. The population on Main Island increased at an exponential rate of r = 0.053 (equivalent to 5.4% per annum) between the first two surveys: counts of pups increased from 487 to 1333, and the breeding area expanded to include several new colonies. Mark-recapture estimates of pup numbers in the two largest colonies in 1989-90 and 1992-93 did not differ statistically. Rates of increase in individual colonies over the 19 or 20 years from 1970 ranged from r = 0.031 (3.1%) to r = 0.256 (29.2%). On the South Neptune Islands, the estimate of pup...
PUP PRODUCTION AND POPULATION TRENDS OF THE AUSTRALIAN FUR SEAL (ARCTOCEPHALUS PUSILLUS DORIFERUS
Marine Mammal Science, 2005
We estimated the number of live Australian fur seal pups using capture-markresights, direct ground counts, or aerial photography at all breeding sites following the pupping season of November-December 2002. Pups were recorded at 17 locations; nine previously known colony sites, one newly recognized colony and seven haul-out sites where pups are occasionally born. In order of size, the colonies were Lady Julia Percy Island (5,899 pups), Seal Rocks (4,882), The Skerries (2,486), Judgment Rocks (2,427), Kanowna Island (2,301), Moriarty Rocks (1,007), Reid Rocks (384), West Moncoeur Island (257), and Tenth Island (124). The newly recognized site was Rag Island, in the Cliffy Group, where we recorded 30 pups. We also recorded pups at the following haul-out sites: Cape Bridge-water (7 pups), Bull Rock (7), Wright Rock (5), Twin Islet (1), The Friars (1), He des Phoques (1), and Montague Island (1). In total, we estimate there were 19,819 (SE = 163) live pups at the time of the counts. We discuss trends in pup numbers and derive current population estimates for the Australian fur seal.
Wildlife Research, 1994
New Zealand fur seals, Arctocephalus forsteri, breed at Cape Gantheaume (36�04'S,137�28'E), Kangaroo Island, South Australia, on broken rock platforms. In 1988-89, pups were born between late November and mid-January, 90% of them over 34 days between 3 December and 6 January. The median date of birth was 21 December. A re-analysis of data for this species from three breeding seasons at the Open Bay Islands (South Island, New Zealand, 43�52'S,l68�53'E) indicates that: (i) the breeding season at Cape Gantheaume occurs 5-12 days later than at the Open Bay Islands, (ii) the period containing 90% of births was the same duration for both populations, and (iii) the median date of birth spanned seven days in three seasons at the Open Bay Islands. In addition, the timing and duration of the pupping season varied within the Cape Gantheaume colony, it being later in recently colonised areas. We suggest that this pattern is a consequence of changes in the age distribution of fem...
Polar Biology, 2009
Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The Wrst breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954-2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is signiWcant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been aVected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.
Wildlife Research, 2006
Since its near extermination by sealing, the New Zealand fur seal (Arctocephalus forsteri) has been recolonising areas of its former range throughout New Zealand and Australia. This study examined fur seal population growth over four breeding seasons spanning 2002-05 at the Ohau Point and Lynch's Reef colonies in Kaikoura and the Horseshoe Bay and Te Oka Bay colonies on Banks Peninsula, on the east coast of New Zealand. Estimates of pup numbers were made using mark-recapture techniques and condition indices were used to assess the body condition of pups in each colony. We found that the Ohau Point and Te Oka Bay colonies are growing exponentially (32% and 47% per annum respectively), reaching nearly 600 pups at Ohau Point and 300 pups at Te Oka Bay, whereas Horseshoe Bay appears stable. Pups born at Ohau Point are consistently heavier and in better condition than their Banks Peninsula counterparts despite the faster rate of growth observed at Te Oka Bay. An El Niño event in 2003 coincided with a drop in mass and condition at the Banks Peninsula colonies, but not at the Kaikoura colony. This discrepancy between colonies in response to environmental conditions suggests that colonyspecific variables at Kaikoura may provide more favourable conditions for rearing pups than on Banks Peninsula. Colony growth and pup condition of the New Zealand fur seal (Arctocephalus forsteri) on the Kaikoura coastline compared with other east coast colonies www.publish.csiro.au/journals/wr
Marine Mammal Science, 1990
Fur seals at Macquarie Island were harvested indiscriminately from the time of its discovery in July 1810 until the supply of animals was exhausted. The identity of the original fur seal is unknown and no specimens exist. The New Zealand fur seal Arctocephalusforsteri has been recorded at the island since 1948 when Australian National Antarctic Research Expeditions (AN ARE) began there. Numbers have increased slowly to about 1200 animals, most of them on North Head peninsula. The species is present throughout the year but does not breed on the island. Breeding colonies of the su bantarctic and antarctic fur seals, A. tropicalis and A. gaze/la, were first recognised in Goat Bay and Secluded Beach on North Head peninsula in 1981-82. These species can generally be distinguished from each other and A.forsteri on the basis of external characters and vocalisations. A. tropicalis has not previously been reported as breeding in Australian waters; A. gaze/la breeds also at Heard Island. In the 1985-86 and 1986-87 summers, the two groups of fur seals (non-breeders and breeders) were equally prevalent on North Head peninsula until late December, when numbers of the non-breeders increased markedly and numbers of the breeders decreased slightly. In these two summers 30 and 37 pups were recorded. In 1986-87, the median pupping date was lO December. Pups were born in six territories, four of which were held for most of December by A. tropicalis bulls and contained 86% of the pups. A. gaze/la bulls were smaller than A. tropicalis bulls. Almost all of the cows were identified as A. gaze/la, only a few A. tropicalis cows being recognised.
Pup density related to terrestrial habitat use by New Zealand fur seals
Canadian Journal of Zoology, 1999
... 1Author to whom all correspondence should be sent at the following address: Antarctic Wildlife Research Unit, School of Zoology, University of Tasmania, PO Box 252-05, Hobart, Tasmania 7001, Australia (e-mail: corey.bradshaw@utas.edu.au). Page 2. ...
Population changes in Subantarctic and Antarctic fur seals at Marion Island
South African Journal of Wildlife Research
Counts at Marion Island during the 2003/04 breeding season indicated a pup production of 16 045 for Subantarctic fur seals, Arctocephalus tropicalis, and 759 for the sympatric population of Antarctic fur seal,A. gazella. While the mean annual rate of increase of 5.2% for the Subantarctic fur seal population at Marion Island for the period 1994/95–2003/04 was approximately half of that recorded between 1951 and the late 1980s, that of the Antarctic fur seal population for the same period continues to be high (17.0%). We suggest that the dissimilarity in population growth between the two species is due to differences in the availability of preferred terrestrial habitat, since their diets are very similar. Together with the neighbouring Prince Edward Island, this archipelago supports a population of approximately 150 000 Subantarctic fur seals, which has grown at a mean annual rate of 5.3% over the past 15 years. The population of Antarctic fur seals numbers approximately 5800, and has...