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Encounter Bay, Australia

Dennis T.E.,5 Bell Court | McIntosh R.R.,La Trobe University | Shaughnessy P.D.,South Australian Museum

Nest productivity among the White-bellied Sea-Eagle (Haliaeetus leucogaster) population on Kangaroo Island (South Australia) was monitored over 11 breeding seasons between 1985 and 1999. Territories were assessed against standardised measures of relative isolation from human disturbance and assigned to Low-, Moderate- or High-disturbance categories. When productivity data were compared between categories, the level of disturbance was found to significantly affect fledging outcomes, with high-disturbance territories having significantly lower fledging success. Of 164 occupied territory-years, 119 (72.6%) were active and fledged 0.8 (mean) young per year. Territories with high-disturbance levels produced eggs less often (65% of territories active cf. 79% active in more isolated locations), fledged fewer young (0.5 young per year cf. 1.1), and had higher rates of nesting failure (46% cf. 13%). These results indicate that to mitigate further Sea-Eagle population decline in South Australia, site-specific habitat management prescriptions, which include buffer-zone refuge provisions, are required to minimise the effects of human activity on breeding outcomes. Such prescriptions need to take into account that, unique to South Australia, most nests are on cliffs in open coastal landscapes with little visual screening over long distance, thus refuge dimensions should be double those prescribed elsewhere for nests in tall forest habitat. © 2011 Royal Australasian Ornithologists Union. Source

Shaughnessy P.D.,CSIRO | Shaughnessy P.D.,South Australian Museum | Goldsworthy S.D.,SARDI Aquatic Sciences Center | Burch P.,SARDI Aquatic Sciences Center | Dennis T.E.,5 Bell Court
Australian Journal of Zoology

The Australian sea lion is an Australian endemic, restricted to South Australia and Western Australia, with 86% of the population in South Australia. It was listed under the Commonwealth Environment Protection and Biodiversity Conservation Act as Vulnerable in February 2005, and the International Union for the Conservation of Nature has listed it as Endangered. Sea lions are taken as bycatch in the gill-net fishery for school shark and gummy shark, and the risk of extinction of breeding colonies is high even from low levels of bycatch. We assessed trends in pup population size at The Pages Islands, a large breeding colony in South Australia. Pup abundance was estimated by direct counting of live and dead pups; the maximum count in each breeding season was used for trend analysis. The average of direct counts of pups in 14 breeding seasons between 1989-90 and 2009-10 was 473 (s.d.≤58.4). There was no trend in pup numbers, contrasting with two other large colonies: Seal Bay, Kangaroo Island (decreasing), and Dangerous Reef (increasing since 2000). The Australian Sea Lion Management Strategy of the Australian Fisheries Management Authority aims to reduce sea lion bycatch in the shark fishery; a key item is a fishery closure around each breeding colony in South Australia. Implementation of the closure around The Pages should lower the risk of bycatch of its sea lions with foraging areas that previously overlapped with the fishery and should allow the colony's population size to increase. © 2013 CSIRO. Source

McIntosh R.R.,La Trobe University | Arthur A.D.,CSIRO | Dennis T.,5 Bell Court | Berris M.,RSD 107 | And 3 more authors.
Marine Mammal Science

The Australian sea lion (Neophoca cinerea) population at Seal Bay Conservation Park, South Australia, is estimated to be declining at a rate of 1.14% per breeding season. To better understand the potential causes of this decline, survival rates were examined to 14 yr of age for eight cohorts marked as pups (aged 0.17 yr) between 1991 and 2002. Apparent yearly survival rates (Φ) varied by cohort for pups from marking to weaning at 1.5 yr (Φ= 0.30-0.67). Postweaning juvenile survival (1.5-3 yr) was 0.89 and survival from 3 to 14 yr was constant (Φ female:male = 0.96:0.89). Φ of pup cohorts was negatively correlated to local sea surface temperature where the sea lions forage (SST) and was especially low for cohort 7 in 2000 (0.30). It is possible that periods of unusually warm oceanographic conditions may be limiting primary production and inhibiting maternal provisioning to pups. Pup survival to weaning is relatively low compared to other otariid species, is likely to limit recruitment, and may be contributing to the decline in pup abundance observed in the colony. © 2012 by the Society for Marine Mammalogy. Source

Shaughnessy P.D.,South Australian Museum | McKenzie J.,235 Robin Road | Lancaster M.L.,University of Adelaide | Goldsworthy S.D.,SARDI Aquatic Sciences Center | Dennis T.E.,5 Bell Court
Australian Journal of Zoology

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. © 2010 CSIRO. Source

Between May 1986 and May 1991 on Kangaroo Island, 284 Hooded Plovers were captured at night and fitted with coloured PVC bands for individual recognition. Of these, 221 were subsequently recorded a total of 2133 times, with the last re-sight record in 2006. Considerable mobility was recorded among the population, including a small number of movements to the mainland, with the furthest distance travelled from place of banding being ∼145 km. Flocks of >20 birds were common in autumn and early winter, often occurring at near-coastal saline lakes where the mollusc Coxiella striata was abundant, or on beach habitats with heavy seagrass accumulations. Flock size and composition were dynamic and included paired birds temporarily absent from breeding beaches. The high proportion of unbanded adults among autumn-winter flocks suggests either a previously overlooked sub-population of non-territorial adults on Kangaroo Island; or a seasonal immigration of birds from elsewhere. When last recorded, eight colour-banded birds were aged 10 years or more, with the oldest aged 15.5 years. Eleven known age young were in adult plumage when aged <1 year (mean 329.1 ± 16.7 days; range 303-352) some of which were paired and fecund (mean age of 346.3 ± 15.4 days; range 336-364). A total of 27 pairs remained together at the same location for consecutive breeding seasons; 16 of these were with the same partner on the same territory over multiple seasons (range 3-6). In addition to known beach breeding habitats, the Hooded Plover flock foraging locations identified in this study appear to be important to sustain the population through the non-breeding season, and therefore need to be considered in habitat management strategies. Source

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