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Populations of Surface-nesting Seabirds at Marion Island, 1994/95–2002/03
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: R. J. M. Crawford J. Cooper B. M. Dyer M. D. Greyling N. T. W. Klages P. G. Ryan S. L. Petersen L. G. Underhill L. Upfold W. Wilkinson M. S. De Villiers S. Du Plessis M. Du Toit T. M. Leshoro A. B. Makhado M. S. Mason D. Merkle D. Tshingana V. L. Ward P. A. WhittingtonDuring the 1990s and early 2000s, populations of surface-nesting seabirds at Marion Island showed different trends, but for the majority of species numbers decreased. Reduced numbers of gentoo penguins Pygoscelis papua, eastern rockhopper penguins Eudyptes chrysocome filholi, Crozet shags Phalacrocorax... -
Counts of Surface-nesting Seabirds Breeding at Prince Edward Island, Summer 2001/02
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: P. G. Ryan J. Cooper B. M. Dyer L. G. Underhill R. J. M. Crawford M. N. BesterThe first midsummer survey of surface-nesting seabirds at Prince Edward Island was conducted during December 2001. It was also the first census for most species since the early 1980s. Despite concerns about the impacts of longline fishing mortality on various... -
Unusual Breeding by Seabirds at Marion Island During 1997/98
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: R. J. M. Crawford C. M. Duncombe Rae D. C. Nel J. CooperIn 1997/98, breeding at subantarctic Marion Island was exceptionally good for five species of seabirds capable of foraging over wide areas and for a tern. The number of king penguin Aptenodytes patagonicus chicks surviving to the start of spring in... -
A tale of two islands: contrasting fortunes for Subantarctic skuas at the Prince Edward Islands
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: PG Ryan --- , South Africa PA Whittington --- , South Africa RJM Crawford --- Department of Environmental Affairs, South AfricaSubantarctic skuas Catharacta antarctica are key predators of burrowing petrels at sub-Antarctic islands, and can be used to monitor the health of burrowing petrel populations. A survey of skuas at the Prince Edward Islands was conducted during December 2008, repeating... -
Rats and prions at Tristan da Cunha Island
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Ben J Dilley --- , South Africa Delia Davies --- , South Africa Julian Repetto --- , United Kingdom (South Atlantic Ocean) George Swain --- , United Kingdom (South Atlantic Ocean) Peter G Ryan --- , South AfricaTristan da Cunha is a 96 km2 volcanic island in the South Atlantic Ocean. Black Rats Rattus rattus reached the island from a shipwreck in 1882 and their depredation of seabirds’ eggs and chicks are likely partly responsible for the... -
Using digital photography to study moult extent in breeding seabirds
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Alexis Osborne --- , South Africa Peter G Ryan --- , South AfricaScoring moult from live birds in the hand takes time, thereby increasing the handling stress to the birds. We show that digital photography can be used to efficiently study moult extent across multiple feather tracts. We photographed the upper wings... -
Dazzled by the light: the impact of light pollution from ships on seabirds at Tristan da Cunha
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Peter G Ryan --- , South Africa E Molly Ryan --- , South Africa James P Glass --- ,Most of the millions of burrow-nesting petrels that breed at Tristan da Cunha are susceptible to light pollution. On dark, misty nights, petrels become disoriented by artificial lights, mainly from ships. From 2013 to 2021 at least 1 823 petrels... -
Long-term changes in petrel populations on Inaccessible Island, Tristan da Cunha, inferred from the diet of Brown Skuas Stercorarius antarcticus
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Peter G Ryan --- University of Cape Town, South AfricaPetrels that breed in burrows and return to their colonies after dark are among the most poorly studied seabirds. Brown Skuas Stercorarius antarcticus (family Stercorariidae) are major predators of burrowing petrels at many seabird breeding islands in the Southern Ocean,...