scholarly journals Foraging ecology of a generalist predator, the female New Zealand fur seal

2002 ◽  
Vol 227 ◽  
pp. 11-24 ◽  
Author(s):  
RG Harcourt ◽  
CJA Bradshaw ◽  
K Dickson ◽  
LS Davis
Keyword(s):  
New Zealand ◽  
Foraging Ecology ◽  
Generalist Predator ◽  
Fur Seal ◽  
New Zealand Fur Seal

Summer foraging behaviour of a generalist predator, the New Zealand fur seal (Arctocephalus forsteri)

2001 ◽  
Vol 28 (6) ◽  
pp. 599 ◽  
Author(s):  
Robert G. Harcourt ◽  
Corey J. A. Bradshaw ◽  
Lloyd S. Davis
Keyword(s):  
New Zealand ◽  
Short Duration ◽  
Resource Availability ◽  
Statistical Power ◽  
Foraging Behaviour ◽  
Time Of Day ◽  
Generalist Predator ◽  
Dive Behaviour ◽  
Fur Seal ◽  
New Zealand Fur Seal

This study examined the dive behaviour of 20 lactating New Zealand fur seals (Arctocephalus forsteri) breeding at Fuchsia Gully (Ohinepuha, 45˚52S, 170˚44E), Otago Peninsula, New Zealand, over five consecutive austral summers (1993/94–1997/98). We examined annual variation in dive behaviour by classifying series of dives into dive bouts using an iterative statistical technique. We found a non-random pattern of dive bouts and bout classification was relatively insensitive to changes in the clustering parameters used. Minimum bouts consisted of at least three dives 10 m occurring within a 20-min period. Bouts were classified into three bout types (clusters) using a multi-variate clustering procedure. These clusters described bouts of: (1) long duration with many dives of medium depth (LONG); (2) short duration with few, shallow dives (SHALLOW); and (3) short duration consisting of long, deep dives and long surface intervals and bottom times (DEEP). Diving was primarily nocturnal, and bout type varied significantly with time of day. The proportion of LONG bouts was greatest at dusk and least near dawn, SHALLOW bouts predominated during the night, and DEEP bouts were of importance near dawn. Few dives occurred during the day. We detected no annual differences in individual parameters of dive behaviour due to low statistical power. We used randomisation tests to assess whether the proportion of each bout type might vary in years of differing prey consumption, but no significant differences were found. Changes in prey composition were detected in two of these years, which suggests that using the dive behaviour of generalist predators to detect changes in resource availability may be a poor option. The high degree of flexibility in foraging behaviour of the New Zealand fur seal means that, inevitably, analyses of dive behaviour will have low statistical power. Changes in foraging behaviour may only be useful to detect very large changes in resource availability. Alternatively, very large sample sizes may be able to detect more subtle changes.

Male-biased sex ratios in New Zealand fur seal pups relative to environmental variation

2003 ◽  
Vol 53 (5) ◽  
pp. 297-307 ◽  
Author(s):  
Corey J. A. Bradshaw ◽  
Robert G. Harcourt ◽  
Lloyd S. Davis
Keyword(s):  
New Zealand ◽  
Sex Ratios ◽  
Environmental Variation ◽  
Fur Seal ◽  
New Zealand Fur Seal

Records of vagrant fur seals (family Otariidae) in South Australia

2014 ◽  
Vol 36 (2) ◽  
pp. 154 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Catherine M. Kemper ◽  
David Stemmer ◽  
Jane McKenzie
Keyword(s):  
New Zealand ◽  
South Australia ◽  
The South ◽  
South Indian Ocean ◽  
Fur Seals ◽  
South Indian ◽  
Fur Seal ◽  
New Zealand Fur Seal ◽  
The Antarctic ◽  
Subantarctic Fur Seals

Two fur seal species breed on the southern coast of Australia: the Australian fur seal (Arctocephalus pusillus doriferus) and the New Zealand fur seal (A. forsteri). Two other species are vagrants: the subantarctic fur seal (A. tropicalis) and the Antarctic fur seal (A. gazella). We document records of vagrant fur seals in South Australia from 1982 to 2012 based primarily on records from the South Australian Museum. There were 86 subantarctic fur seals: 49 specimens and 37 sightings. Most (77%) were recorded from July to October and 83% of all records were juveniles. All but two specimens were collected between July and November. Sightings were prevalent during the same period, but there were also nine sightings during summer (December–February), several of healthy-looking adults. Notable concentrations were near Victor Harbor, on Kangaroo Island and Eyre Peninsula. Likely sources of subantarctic fur seals seen in South Australia are Macquarie and Amsterdam Islands in the South Indian Ocean, ~2700 km south-east and 5200 km west of SA, respectively. There were two sightings of Antarctic fur seals, both of adults, on Kangaroo Island at New Zealand fur seal breeding colonies. Records of this species for continental Australia and nearby islands are infrequent.

Colony growth and pup condition of the New Zealand fur seal (Arctocephalus forsteri) on the Kaikoura coastline compared with other east coast colonies

2006 ◽  
Vol 33 (6) ◽  
pp. 497 ◽  
Author(s):  
L. J. Boren ◽  
C. G. Muller ◽  
N. J. Gemmell
Keyword(s):  
New Zealand ◽  
Body Condition ◽  
East Coast ◽  
Colony Growth ◽  
The Body ◽  
Fur Seal ◽  
Seal Population ◽  
Condition Indices ◽  
New Zealand Fur Seal ◽  
Breeding Seasons

Abstract.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 colony-specific variables at Kaikoura may provide more favourable conditions for rearing pups than on Banks Peninsula.

A survey of the oral cavity microbiome of New Zealand fur seal pups ( Arctocephalus forsteri )

2019 ◽  
Vol 36 (1) ◽  
pp. 334-343 ◽  
Author(s):  
Arsalan Emami‐Khoyi ◽  
Isma Benmazouz ◽  
James G. Ross ◽  
Laura J. Boren ◽  
Elaine C. Murphy ◽  
...  
Keyword(s):  
New Zealand ◽  
Oral Cavity ◽  
Fur Seal ◽  
New Zealand Fur Seal

Changes in the abundance of New Zealand fur seals, Arctocephalus forsteri, on Kangaroo Island, South Australia

1995 ◽  
Vol 22 (2) ◽  
pp. 201 ◽  
Author(s):  
PD Shaughnessy ◽  
SD Goldsworthy ◽  
JA Libke
Keyword(s):  
New Zealand ◽  
South Australia ◽  
Early Years ◽  
Mark Recapture ◽  
Fur Seals ◽  
Fur Seal ◽  
Rate Of Increase ◽  
New Zealand Fur Seal ◽  
Breeding Seasons ◽  
Made In

Kangaroo Island was an important seal-harvesting site during the early years of European colonisation of Australia. A recent survey of the New Zealand fur seal, Arctocephalus forsteri, in South and Western Australia indicates that Kangaroo I. is still an important centre for the species. In order to determine changes in the abundance of the population, numbers of pups were determined at four colonies on Kangaroo Island by mark-recapture in up to five breeding seasons from 1988-89 to 1992-93. Clipping was the preferred technique for mark-recapture estimation of pups because it was quick, easy and effective. Recaptures were conducted visually; they were repeated several times in each season to improve precision of the estimates. No pups were marked between recaptures in order to minimise disturbance. Assumptions made in estimating population size by the mark-recapture technique pertinent to this study are reviewed. Pup numbers increased at three colonies: at Cape Gantheaume, from 458 to 867 over five years (with exponential rate of increase r = 0.16, n = 5); at Nautilus North, from 182 to 376 over five years (at r = 0.19, n = 4); and at North Casuarina Islet, from 442 to 503 over four years (at r = 0.043, n = 2). Rates of increase in the first two colonies are similar to those at the most rapidly increasing fur seal populations in the Southern Hemisphere. The Kangaroo I. population is estimated to be 10000 animals in 1992-93. It is likely to be at the recolonisation phase of growth, with high rates of increase at individual colonies (or parts of colonies) resulting from local immigration. As space does not appear to be limiting expansion in these colonies, fur seal numbers may continue to increase there.

Australian fur seals establish haulout sites and a breeding colony in South Australia

2010 ◽  
Vol 58 (2) ◽  
pp. 94 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Jane McKenzie ◽  
Melanie L. Lancaster ◽  
Simon D. Goldsworthy ◽  
Terry E. Dennis
Keyword(s):  
Mitochondrial Dna ◽  
New Zealand ◽  
South Australia ◽  
Breeding Colony ◽  
Mitochondrial Dna Control Region ◽  
Sea Lions ◽  
Neophoca Cinerea ◽  
Fur Seals ◽  
Fur Seal ◽  
New Zealand Fur Seal

Australian fur seals (Arctocephalus pusillus doriferus) breed on Bass Strait islands in Victoria and Tasmania. They have been recorded in South Australia (SA) for many years as non-breeding visitors and on Kangaroo Island frequently since 1988, mostly in breeding colonies of the New Zealand fur seal (A. forsteri) which is the most numerous pinniped in SA. Australian fur seals have displaced New Zealand fur seals from sections of the Cape Gantheaume colony on Kangaroo Island. North Casuarina Island produced 29 Australian fur seal pups in February 2008. Australian fur seal pups were larger than New Zealand fur seal pups in the same colony and have been identified genetically using a 263-bp fragment of the mitochondrial DNA control region. North Casuarina Island has been an important breeding colony of New Zealand fur seals, but pup numbers there decreased since 1992–93 (contrary to trends in SA for New Zealand fur seals), while numbers of Australian fur seals there have increased. This study confirms that Australian fur seals breed in SA. The two fur seal species compete for space onshore at several sites. Australian fur seals may compete for food with endangered Australian sea lions (Neophoca cinerea) because both are bottom feeders.

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