Antarctic petrel (Thalassoica antarctica)
Classified as Least Concern (LC) on the IUCN Red List (1).
One of the most southerly nesting birds the Antarctic petrel (Thalassoica antarctica) breeds in the mountainous regions of the Antarctic (2).
The Antarctic petrel has a faded brown head and mantle with white bars on wings with a thick brown leading edge. During the summer the black colouration fades to a dull yellowish-brown (3). The plumage of males and females is identical but males are slightly larger than females (4).
The Antarctic petrel occupies an extensive range and can be found along the Antarctic coastline and surrounding islands. It also nests up to 250 kilometres inland (5).
Antarctic petrel colonies are found on steep, exposed slopes, more than six metres above sea level, so that the petrels can take off (6). Nests are commonly found on rock or cliff faces (5). The Antarctic environment is harsh and few animals can survive here. Temperatures experienced by the Antarctic petrel are regularly below 0 degrees Celsius and can drop to minus 25 degrees Celsius (6).
The Antarctic petrel nests in dense colonies (6). One of the largest known is located inland at Svarthamaren in Queen Maud Land, Antarctica where up to 255,000 breeding pairs have been observed. There are 35 known breeding colonies, mostly in East Antarctica, but there are probably more to be discovered (7).
Although generally considered to be monogamous, female Antarctic petrels will sometimes mate with a neighbouring male. Due to the high proportion of females in some populations, not every female is able to breed each season. Occasionally a breeding female will be joined by an unsuccessful female providing the opportunity to improve its parenting skills (8).
The female Antarctic petrel lays one egg (9) in the last ten days of November (10) and the egg hatches in early January (6) (10). After hatching, the adults take turns to remain at the nest while the other forages for food (3).These foraging trips may cover large distances of up to 3000 kilometres (11). Chicks fledge in late February to early March (10).
Plunging into the water to grab its prey or seizing it from the surface of the water, the Antarctic petrel feeds on fish, Antarctic krill (Euphausia superba) and occasionally squid (5). Inland colonies feed mostly on crustaceans, whereas birds living on pack ice feed mainly on fish (11). In some colonies, chicks may eat proportionally more fish than their parents, because fish provide slightly more energy and protein than krill and considerably more calcium, which is required for growth (12).
Adult Antarctic petrels generally have high survival rates (9). Although there are no available data concerning hatching or fledgling success in this species, it is known that south polar skuas (Stercorarius maccormicki) predate eggs and chicks, targeting nests that are less sheltered (13).
There is little information available regarding potential threats to the survival of this species. In 1999, it was estimated that there were between 10 and 20 million Antarctic petrels (10), and although there have been no more recent estimates it does not appear that the species’ numbers have changed significantly (7).
Like other marine birds, it is possible that the Antarctic Petrel may be affected by longline fishing practices in the Southern Ocean (14).
Climate change also poses a potential threat to the habitat of the Antarctic petrel and may affect the behaviour of this bird and other animals inhabiting the Antarctic (15). It has been noted that birds breeding in East Antarctica, including the Antarctic petrel, tended to arrive and breed later in 2004 than in 1950, a trend that has been linked to climate change (16). Warming of the Southern Ocean has also been linked to a reduction in krill, a prey item of the Antarctic petrel (17).
Currently there are no known measures in place for the conservation of the Antarctic petrel owing to its large population numbers and extensive range (1). However, members of the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) are monitoring the effects of fishing in the Southern Ocean and are working towards reducing seabird bycatch (18).
More information on the Antarctic petrel and other bird species:
BirdLife International - Antarctic petrel:
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- Bycatch: in the fishing industry, the part of the catch made up of non-target species.
- Crustaceans: diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
- Monogamous: having only one mate during a breeding season, or throughout the breeding life of a pair.
- Pack ice: sea ice that floats on the surface of the water. Often formed from large pieces of ice that consolidate into a single ice mass, pack ice typically moves with currents, tides and wind.
IUCN Red List (April, 2011)
- Weathers, W.W., Gerhart, K.L. and Hodum, P.J. (2000) Thermoregulation in Antarctic fulmarine petrels. Journal of Comparative Physiology B: Biochemical, Systematic, and Environmental Physiology, 170(8): 561-572.
- Warham, J. (1990) The Petrels: Their Ecology and Breeding Systems. Academic Press Limited, London.
- Lorentsen, S-H. & Røv, N. (1994) Sex determination of Antarctic Petrels Thalassoica antarctica by discriminant analysis of morphometric characters. Polar Biology, 14(2): 143-145.
BirdLife International (March, 2011)
- Hodum, P.J. (2002) Breeding biology of high-latitude Antarctic fulmarine petrels (Procellariidae). Journal of Zoology, 256: 139-149.
- Brooke, M. (2004) Albatrosses and Petrels across the World. Oxford University Press, Oxford.
- Lorentsen, S-H., Amundsen, T., Anthonisen, A., Lifjeld, J. T. (2000) Molecular evidence for extrapair paternity and female-female pairs in Antarctic petrels. Auk, 117(4): 1042-1047.
- Hodum, P.J. and Weathers, W.W. (2003) Energetics of nestling growth and parental effort in Antarctic fulmarine petrels. Journal of Experimental Biology, 206: 2125-2133.
- van Franeker, J.A., Gavrilo, M., Mehlum, F., Veit, R.R. and Woehler, E.J. (1999) Distribution and abundance of the Antarctic petrel. Waterbirds, 22(1): 14-28.
- Lorentsen, S-H., Klages, N. & Røv, N. (1998) Diet and prey consumption of Antarctic petrels Thalassoica antarctica at Svarthamaren, Dronning Maud Land, and at sea outside the colony. Polar Biology, 19(6): 414-420.
- Hodum, P.J. and Hobson, K.A. (2000) Trophic relationships among Antarctic fulmarine petrels: insights into dietary overlap and chick provisioning strategies inferred from stable-isotope (d15N and d13C) analyses. Marine Ecology Progress Series, 198: 273-281.
- Varpe, Ø. and Tveraa, T. (2005) Chick survival in relation to nest site: is the Antarctic petrel hiding from its predator? Polar Biology, 28(5): 388-394.
Commission for the Conservation of Antarctic Marine Living Resources (November, 2011)
- Trathan, P.N. and Agnew, D. (2010) Climate change and the Antarctic marine ecosystem: an essay on management implications. Antarctic Science, 22(4): 387-398.
- Barbraud, C. and Weimerskirch, H. (2006) Antarctic birds breed later in response to climate change. Proceedings of the National Academy of Sciences, 103(16): 6248-6251.
- Atkinson, A., Siegel, V., Pakhomov, E. and Rothery, P. (2004) Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature, 432:100–103.
- Waugh, S.M., Baker, G.B., Gales, R. and Croxall, J.P. (2008) CCAMLR process of risk assessment to minimise the effects of longline fishing mortality on seabirds. Marine Policy, 32(5): 442-454.