Biology
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Atlantic petrels are winter breeders, returning to their colonies from February to March in order to mate (3). Single eggs are laid from June to July, with young hatching in August and September, and fledging in December and January (3) (5). The birds are exclusively nocturnal whilst on land (5). Chicks grow at a very slow rate, suggesting poor at-sea feeding conditions (5). The age of first breeding, breeding frequency and longevity are not yet known for this species (2).
Squid forms the bulk of the diet, although some crustaceans and fish will also be taken (2), and the Atlantic petrel possesses physical and behavioural adaptations geared towards catching such prey. The species' towering flight style gives it a commanding field of view, useful in detecting widely dispersed prey (3). Furthermore, few other gadfly petrels in the region have such an elongated bill as this species, which is equipped with a strongly hooked tip, thought to be an adaptation to snatching live, slippery squid from the sea surface (3).
Conservation
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Gough Island is both a Nature Reserve and World Heritage Site, and while this provides good protection from human disturbance, it does not offer the Gough bunting any protection from the mouse predation that is driving it towards extinction (2). A study of the mice conducted by The Royal Society for the Protection of Birds (RSPB) and funded by the UK government's Overseas Territories Environment Programme has shown that their eradication from the island is feasible. Unfortunately, however, until adequate funding is acquired this will not occur (7). Gough Island is widely recognised as having one of the most diverse bird colonies in the world, including four endangered species, and every effort should therefore be made to protect it and the rich biodiversity it hosts (8).
Description
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The Atlantic petrel is one of the largest gadfly petrels (Pterodroma species), recognised by its striking white breast and abdomen that contrast with the uniformly black-brown plumage of the rest of the body (4). Particularly sharp colour demarcation exists from the brown upper breast to the white lower breast and belly (2). Sexes are alike (3).
Habitat
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This bird nests in colonies on islands, but is otherwise pelagic (2). Nesting occurs in burrows dug in peaty soils in fern-bush vegetation from 50 to 300 metres above sea level on Gough, and at higher elevations on Tristan (2).
Range
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The Atlantic petrel is a seabird predominantly restricted to the South Atlantic, ranging from the east coast of South America to the west coast of Africa (2). Until recently, a breeding population existed on Tristan da Cunha, but this is now believed to be extinct. Today, Gough Island is the only location where this species still breeds, with an estimated population of around 1.8 million pairs (2).
Status
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Classified as Endangered (EN) on the IUCN Red List (1).
Threats
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Although still common, the Atlantic petrel qualifies as Endangered because it has a very small breeding range, with the vast majority of the population on just one island (2). Such a limited range places the bird at risk from chance events such as natural disasters or the introduction of mammalian predators (2) (6). On Gough, predation by the introduced house mouse (Mus musculus) is having a severe effect on the Atlantic petrel's breeding success, with just two percent of the chicks reaching fledging in 2007 (2). The large population of native southern skua (Catharacta antarctica) are also known to feed on seabirds including the Atlantic petrel (2).
On Tristan Island, where the Atlantic petrel was once common, it was likely to have been driven into decline by hunting, as it was formerly one of the few sources of food for the islanders during winter (6). Although this exploitation has abated, predation by introduced rats appears to have driven the island's population to extinction (2).
Atlantic petrel
provided by wikipedia EN
The Atlantic petrel (Pterodroma incerta) is a gadfly petrel endemic to the South Atlantic Ocean. It breeds in enormous colonies on Tristan da Cunha and Gough Island, and ranges at sea from Brazil to Namibia, with most records at sea being to the west of the breeding islands, and along the subtropical convergence.[2] Adults are about 43 cm long, powerful, large, stocky, dark in color with white belly.[3] Their head can appear to be grey in worn plumage. Brown undercoating of wings and tail. These petrels can live on average of 15 years of age.[3]
Population trends
Although the species exists in large numbers, the world population being estimated at around 5 million birds, it is listed as endangered by the IUCN. It is restricted to just two breeding islands and has declined historically due to exploitation for food. According to some studies, there are roughly 1.1 million mating pairs, but only about 25% of eggs survived.[4] This is making their large population numbers decrease rapidly. Gough Island was the location of study, since other islands are inaccessible due to the steep cliffs.[5] Due to reproduction mortality, this species can become locally extinct making their home range smaller.
Habitat and ecology
The species feeds mostly on squid, which comprise 87% of its diet in some studies; it will also feed on lanternfishes (Myctophidae) as they ascend to the surface at night, as well as on crustaceans and some fish.[2] This species is known for its nocturnal breeding habits.[4] The nesting locations are between 50 and 300 meters above sea level, located on cliffsides on Gough Island and formerly, at Tristan da Cunha it was upwards of 700 meters.[6] It nests in burrows dug in peaty soils in fern-bush vegetation.
Predators and threats
It is currently threatened by introduced house mice, which prey on recently-hatched chicks.[4] Mouse predation is particularly prevalent on Gough Island, whose mice have rapidly evolved to be about twice the size of their mainland counterparts through a phenomenon commonly known as island syndrome.[7]
Given their small breeding range, severe hurricanes also pose an intermittent threat to breeding populations.[8] Increasingly severe storms also threaten the availability and predictability of food sources such as squid.[3]
Conservation efforts
Starting around the 1970s, on Tristan da Cunha, they have programs to teach and learn about this species and why it is important for the ecosystem.[3] They also educate about the dangers that the birds are facing and research ways to implement protection for them in the future. Considering their populations numbers are high, their declining population is thought to be due to the mortality rate of eggs and young. Gough Island is a nature reserve and World Heritage site, there is a field station on this island to observe the Atlantic Petrels population.[6] Research on the House mouse is important to finding ways in reducing these predators' effect on the Atlantic Petrels.[3]
Actions proposed
Further studies on the House mouse and find ways to eradicate mice on Gough Island. Minimize the risk of introducing other species that are invasive to Gough Island and find methods better to understand this species on their habits.[4] Use measures of demographic mapping to better understand the island along with population trends.
It was formerly classified as a vulnerable species by the IUCN.[9] However, new research demonstrated the severe impact of predation by mice. Consequently, it was uplisted to endangered status in 2008.[10]
Footnotes
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^ BirdLife International (2019). "Pterodroma incerta". IUCN Red List of Threatened Species. 2019: e.T22698084A152715347. doi:10.2305/IUCN.UK.2019-3.RLTS.T22698084A152715347.en. Retrieved 11 November 2021.
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^ a b Klages, N.T.W.; Cooper, J. (1997). "Diet of the Atlantic petrel Pterodroma Incerta during breeding at South Atlantic Gough Island" (PDF). Marine Ornithology. Retrieved 2016-04-01.
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^ a b c d e IUCN (2019-06-14). "Pterodroma incerta: BirdLife International: The IUCN Red List of Threatened Species 2019: e.T22698084A152715347". doi:10.2305/iucn.uk.2019-3.rlts.t22698084a152715347.en.
{{cite journal}}: Cite journal requires |journal= (help) -
^ a b c d Cuthbert, Richard; Hilton, Geoff (2004-06-01). "Introduced house mice Mus musculus: a significant predator of threatened and endemic birds on Gough Island, South Atlantic Ocean?". Biological Conservation. 117 (5): 483–489. doi:10.1016/j.biocon.2003.08.007. ISSN 0006-3207.
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^ Dilley, Ben J.; Davies, Delia; Bond, Alexander L.; Ryan, Peter G. (2015-06-30). "Effects of mouse predation on burrowing petrel chicks at Gough Island". Antarctic Science. 27 (6): 543–553. doi:10.1017/s0954102015000279. ISSN 0954-1020. S2CID 86782992.
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^ a b "Cooper, J. & Ryan, P.G.Management plan for the Gough Island Wildlife Reserve. Government of Tristan da Cuhna. (1994). 96pages. No price indicated. ISBN 09 03359 38 3". Antarctic Science. 6 (4): 544. December 1994. doi:10.1017/s0954102094260807. ISSN 0954-1020. S2CID 246043428.
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^ Link to external site, this link will open in a new window (April 2021). "Evolution of boldness and exploratory behavior in giant mice from Gough Island". doi:10.1007/s00265-021-03003-6. ISSN 0340-5443.
{{cite journal}}: Cite journal requires |journal= (help) -
^ Bugoni, Leandro; Sander, Martin; Costa, Erli Schneider (December 2007). "Effects of the First Southern Atlantic Hurricane on Atlantic Petrels (Pterodroma Incerta)". The Wilson Journal of Ornithology. 119 (4): 725–729. doi:10.1676/06-141.1. ISSN 1559-4491. S2CID 85595992.
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^ BLI (2007)
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^ BLI (2008a,b)
References
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Atlantic petrel: Brief Summary
provided by wikipedia EN
The Atlantic petrel (Pterodroma incerta) is a gadfly petrel endemic to the South Atlantic Ocean. It breeds in enormous colonies on Tristan da Cunha and Gough Island, and ranges at sea from Brazil to Namibia, with most records at sea being to the west of the breeding islands, and along the subtropical convergence. Adults are about 43 cm long, powerful, large, stocky, dark in color with white belly. Their head can appear to be grey in worn plumage. Brown undercoating of wings and tail. These petrels can live on average of 15 years of age.
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Breeding Category
provided by World Register of Marine Species
Vagrant
Woehler E.J. (compiler) 2006. Species list prepared for SCAR/IUCN/BirdLife International Workshop on Antarctic Regional Seabird Populations, March 2005, Cambridge, UK.
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Habitat
provided by World Register of Marine Species
breeding on Tristan da Cunha
van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO).
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- WoRMS Editorial Board
IUCN Red List Category
provided by World Register of Marine Species
Vulnerable
Woehler E.J. (compiler) 2006. Species list prepared for SCAR/IUCN/BirdLife International Workshop on Antarctic Regional Seabird Populations, March 2005, Cambridge, UK.
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