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Статті в журналах з теми "Cape Gantheaume"
1
Goldsworthy, SD, and PD Shaughnessy. "Breeding biology and haul-out pattern of the New Zealand fur seal, Arctopehalus forsteri, at Cape Gantheaume, South Australia." Wildlife Research 21, no. 3 (1994): 365. http://dx.doi.org/10.1071/wr9940365.
Повний текст джерелаАнотація:
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 females through the colony. The sex ratio of pups born in the colony over four breeding seasons did not differ significantly from 1:l. Females were mated on average 7.4 days after birth and left for sea 2.3 days later. The mean date of observed matings was 29 December; copulations lasted about 13 min. The operational sex ratio (OSR) in the colony was 8.6 females per territorial male (the maximum ratio of territorial males to pups was 1:16), which was within the range reported for other southern fur seal species. In two consecutive breeding seasons, the estimated fecundity rate of adult females averaged 67%. Non-breeding animals (sub-adult males, juveniles and yearlings) occurred in areas not occupied by breeding animals. The number of juveniles ashore increased after the breeding season, but no pattern was found for sub-adults and yearlings. Yearlings were uncommon in the colony at all times; it is suggested that they are mostly pelagic and do not moult in their second year.
2
Shaughnessy, Peter D., and Simon D. Goldsworthy. "Increasing abundance of pups of the long-nosed fur seal (Arctocephalus forsteri) on Kangaroo Island, South Australia, over 26 breeding seasons to 2013–14." Wildlife Research 42, no. 8 (2015): 619. http://dx.doi.org/10.1071/wr14209.
Повний текст джерелаАнотація:
Context Long-nosed (or New Zealand) fur seals breed on the southern coast of Australia, in New Zealand and on its subantarctic islands. They are recovering from over-harvesting that occurred in the early nineteenth century. Aims We estimated the rate of increase of the population at two colonies on Kangaroo Island, South Australia: Cape Gantheaume and Cape du Couedic. Methods From 1988–89 to 2013–14, pup abundance was estimated using a mark–resight procedure with multiple resights in large aggregations of pups and by direct counting in small aggregations. Key results At Cape Gantheaume, pup numbers increased by a factor of 10.7 from 457 to 5333 over 26 breeding seasons and the exponential rate of increase averaged 10.0% per annum (p.a.). Between 1988–89 and 1997–98, the population increased at 17.3% p.a., after which the increase was 7.2% p.a. At Cape du Couedic, pup numbers increased by a factor of 12.8 from 295 to 4070 over 21 breeding seasons at 11.4% p.a. Between 1988–89 and 1997–98, the increase averaged 14.2% p.a., after which it was 9.6% p.a. These increases have been accompanied by expansion in sub-colonies that existed in January 1989 and establishment of several new sub-colonies. Increases are likely to continue on Kangaroo Island. Conclusions There are few examples of increasing population levels for Australian native mammals and this is one of the best documented. It demonstrates that fur seal populations can recover from uncontrolled harvesting provided breeding habitat ashore is protected. Implications Fur seals interfere with fishers, disturb farmed tuna in aquaculture pens, and prey on little penguins.
3
Troy, S. K., R. Mattlin, P. D. Shaughnessy, and P. S. Davie. "Morphology, age and survival of adult male New Zealand fur seals, Arctocephalus forsteri, in South Australia." Wildlife Research 26, no. 1 (1999): 21. http://dx.doi.org/10.1071/wr97103.
Повний текст джерелаАнотація:
Nineteen adult male New Zealand fur seals, Arctocephalus forsteri, were marked and measured at the start of the breeding seasons in November 1992 and 1993 at Cape Gantheaume, Kangaroo Island in South Australia. The age of each seal was estimated from the number of cementum layers in a post-canine tooth. The males that were attempting to hold territories were 7–15 years old and the heaviest was 160 kg. The mass of males could be predicted accurately from linear measurements and several predictive equations enable estimation of mass in the field. The mean annual survival rate for adult male New Zealand fur seals was 76%, which is higher than that in other fur seal species, perhaps reflecting the expanding nature of the A. forsteri population in Australia.
4
Baylis, A. M. M., B. Page, and S. D. Goldsworthy. "Effect of seasonal changes in upwelling activity on the foraging locations of a wide-ranging central-place forager, the New Zealand fur seal." Canadian Journal of Zoology 86, no. 8 (August 2008): 774–89. http://dx.doi.org/10.1139/z08-055.
Повний текст джерелаАнотація:
Lactating New Zealand fur seals ( Arctocephalus forsteri (Lesson, 1828)) that breed at Cape Gantheaume, South Australia, experience broad-scale seasonal changes in ocean productivity. To assess how seasonal changes in ocean productivity influenced foraging behaviour, 18 lactating New Zealand fur seals were fitted with satellite transmitters and time–depth recorders (TDRs). Using temperature and depth data from TDRs, we used the presence of thermoclines as a surrogate measure of upwelling activity in continental-shelf waters. During the austral autumn 80% of lactating fur seals foraged on the continental shelf (114 ± 44 km from the colony), in a region associated with the Bonney upwelling. In contrast, during winter months seals predominantly foraged in oceanic waters (62%), in a region associated with the Subtropical Front (460 ± 138 km from the colony). Our results indicate that lactating New Zealand fur seals shift their foraging location from continental-shelf to oceanic waters in response to a seasonal decline in productivity over the continental shelf, attributed to the cessation of the Bonney upwelling. This study identified two regions used by lactating New Zealand fur seals: (1) a nearby and seasonally productive upwelling system and (2) a distant and permanent oceanic front.
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Shaughnessy, Peter D., Jane McKenzie, Melanie L. Lancaster, Simon D. Goldsworthy, and Terry E. Dennis. "Australian fur seals establish haulout sites and a breeding colony in South Australia." Australian Journal of Zoology 58, no. 2 (2010): 94. http://dx.doi.org/10.1071/zo10017.
Повний текст джерелаАнотація:
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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Baylis, A. M. M., B. Page, K. Peters, R. McIntosh, J. Mckenzie, and S. Goldsworthy. "The ontogeny of diving behaviour in New Zealand fur seal pups (Arctocephalus forsteri)." Canadian Journal of Zoology 83, no. 9 (September 1, 2005): 1149–61. http://dx.doi.org/10.1139/z05-097.
Повний текст джерелаАнотація:
This study investigated the development of diving in 21 New Zealand fur seal pups, Arctocephalus forsteri (Lesson, 1828), prior to weaning at Cape Gantheaume, Kangaroo Island. Diving behaviour was examined using time–depth recorders, which were deployed during two time periods, 5 months prior to weaning (n = 6) and 2 months prior to weaning (n = 15). Scats were also examined to assess whether fur seal pups foraged prior to weaning. The maximum dive depth attained was 44 m, while the maximum dive duration was 3.3 min. Immediately prior to weaning, fur seal pups spent a greater proportion of their time diving at night, and concomitantly several measures of diving performance also increased. In general, pups dived successively deeper (6–44 m between June and September), and the average number of dives per day, dive frequency, and vertical distance travelled increased. Prey remains were present in approximately 30% of scats and indicated that some pups were foraging as early as June (5–6 months of age, approximately 4–5 months prior to weaning). Of the scats that contained prey remains, fish (South American pilchard, Sardinops sagax (Jenyns, 1842); Australian anchovy, Engraulis australis (White, 1790); and redbait, Emmelichthys nitidus Richardson, 1845) accounted for 43% of the prey items found, crustaceans accounted for 36%, and cephalopods (Gould's squid, Nototodarus gouldi (McCoy, 1888)) accounted for 20%.
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Shaughnessy, PD,, M. Berris, and T. E. Dennis. ". Predation on Australian sea lions Neophoca cinerea by white sharks Carcharodon carcharias in South Australia." Australian Mammalogy 29, no. 1 (2007): 69. http://dx.doi.org/10.1071/am07008.
Повний текст джерелаАнотація:
From January 1988 to December 2002, 182 Australian sea lions Neophoca cinerea with injuries attributable to white sharks Carcharodon carcharias were recorded in the N. cinerea colony at Seal Bay, Kangaroo Island. The mean number per month was 1.0 (s.d. 1.3), and the number per calendar year varied from 5 to 25 (mean 12.1, s.d. 6.1). The incidence was highest in summer (December to February) and autumn (March to May). The month with the greatest incidence of injured sea lions was January, when it was 17% of the total. This coincides with the higher proportion of white shark records around Kangaroo Island in summer and autumn than in other seasons (Bruce 1992). Adult female and juvenile sea lions were attacked most frequently, with 38% and 26%, respectively. Adult females pass through the waters near the colony more frequently than other sea lions, which makes them more susceptible than other age-sex groups to attacks by white sharks. Most (42%) injuries were to the head and central parts of the sea lions' bodies and 39% were to the rear of their bodies ('rear trunk' and 'hind flippers' areas). The stomach contents of a white shark caught in a bottom-set monofilament gill-net at Cape Gantheaume, Kangaroo Island in April 1992 included two N. cinerea pups aged 10-12 months. They formed about 75% of the shark?s stomach contents.
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Shaughnessy, PD, SD Goldsworthy, and JA Libke. "Changes in the abundance of New Zealand fur seals, Arctocephalus forsteri, on Kangaroo Island, South Australia." Wildlife Research 22, no. 2 (1995): 201. http://dx.doi.org/10.1071/wr9950201.
Повний текст джерелаАнотація:
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.
Дисертації з теми "Cape Gantheaume"
1
Plotz, Roan. "Growth and Fasting Strategies of New Zealand Fur Seal, Arctocephalus forsteri, Pups at Cape Gantheaume, Kangaroo Island." Thesis, 2003. https://vuir.vu.edu.au/39233/.
Повний текст джерелаАнотація:
New Zealand fur seals (Arctocephalus forsteri) show pronounced inter-sexual differences in adult body size, and males will potentially mate with many females. Consequently, selection is thought to act differently upon pups during growth. Little is known about how male and female fur seal pups conserve energy, and use milk for growth especially as they fast for significant periods. There has been a plethora of studies that have viewed pinnipeds as ideal models for the differential investment theory, but the evidence remains equivocal. This study investigated a species that has shown some support for differential investment in the past, in the form of pup growth and maternal attendance behaviour, and looked at the potential that these intersexual differences are due to differential utilisation of maternal resources (different body compositions) and/or differential fasting strategies by pups, which may be determined by fasting mass loss rates. This study hopes to encompass both aspects of differential investment, such as maternal attendance, as well as differential fasting strategies of pups by looking at their fasting mass loss rates. This study found that males were larger and longer throughout the lactation period, yet grew at the same rate as females. There was no detectable intersexual difference in the maternal provisioning provided by mothers, in the form of attendance. There was some evidence that males and females have different fasting strategies, in that females, from a subset of pups exhibited significantly higher mass specific mass loss rates. This finding should be treated with caution however, as sample size was low, and cross sectional samples revealed no significant differences. Furthermore, study of the activity rates of the same pups over the duration of the fast, found no significant intersexual differences in activity rates. These results suggest that further studies are needed that encompass both aspects of differential investment theory, as well as differential utilisation by pups.