| Southern giant petrel | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Procellariiformes |
| Family: | Procellariidae |
| Genus: | Macronectes |
| Species: | M. giganteus |
| Binomial name | |
| Macronectes giganteus (Gmelin, 1789) | |
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| Global map ofeBird reports Year-Round Range Summer Range Winter Range | |
Thesouthern giant petrel (Macronectes giganteus), also known as theAntarctic giant petrel,giant fulmar,stinker, andstinkpot,[2] is a largeseabird of the southern oceans. Its distribution overlaps broadly with the similarnorthern giant petrel, though it overall is centered slightly further south. Adults of the two species can be distinguished by the colour of theirbill-tip: greenish in the southern and reddish in the northern.
The southern giant petrel wasformally described in 1789 by the German naturalistJohann Friedrich Gmelin. He placed it with all the other petrels in thegenusProcellaria and coined thebinomial nameProcellaria gigantea.[3] Gmelin cited the "giant petrel" that had been described and illustrated in 1785 by the English ornithologistJohn Latham in hisA General Synopsis of Birds.[4][5]
The southern giant petrel is now placed with thenorthern giant petrel in the genusMacronectes that was introduced in 1905 by the American ornithologistCharles Wallace Richmond.[6][7][8] The genus nameMacronectes combines theAncient Greekmakros meaning "great" andnēktēs meaning "swimmer". The specific epithetgiganteus isLatin, derived from Greek "gigas", and means "gigantic".[9] The species ismonotypic: nosubspecies are recognised.[8]
The southern giant petrel measures 86 to 99 cm (34–39 in) with a wingspan of 185 to 205 cm (6 ft 1 in – 6 ft 9 in). Both this and the northern giant petrel vary considerably in size, with southern colonies averaging larger than northern colonies, in line withBergmann's rule. Due to the large amount of size variability, it is difficult to determine which is the larger species, but the largest-bodied colonies of the southern species are slightly larger on average, in both mass and linear dimensions, than the largest in the northern giant petrel.
The males tend to be larger but, body mass can vary widely, from 2.3 to 5.6 kg (5.1–12.3 lb), with males averaging larger than females. The largest average weights come fromMacquarie Island, where 20 males averaged 5.14 kg (11.3 lb) and 21 females averaged 4.2 kg (9.3 lb).[10][11] On theSouth Orkney Islands, 37 males averaged 4.94 kg (10.9 lb) and 37 females averaged 3.85 kg (8.5 lb). In contrast, inPatagonia, 15 males averaged 3.5 kg (7.7 lb) and 21 females averaged 2.5 kg (5.5 lb).[12] However another study from Patagonia, found that 26 males averaged 4.2 kg (9.3 lb) and 27 females averaged 3.7 kg (8.2 lb).[13] They have a very large yellowbill, with a green tip and greyish-brown legs.[14][15]
There are two differentmorphs, the dark which resembles thenorthern giant petrel, and the more distinct light morph. On the dark morph the upper breast, head and neck are light with the remainder of itsplumage being mottled brown.[16] The leading edge of its wing is lighter as is the base of the innerprimaries, on the underside. The light morph is rarer and very distinct with only slight black speckles on an otherwise all white look. As juveniles, the dark morph starts off more sooty brown and pales as it ages.[14] Both giant petrels have strong legs and can move around on land effectively.[16] Finally, when in flight thisspecies has a somewhathunchbacked appearance.[17]
It, like all members of theProcellariiformes, have features that set them apart from other birds. First, they have nasal passages callednaricorns, that attach to the upper bill. The nose holes on the petrels are on the top of the bill. The bills of all Procellariiformes are also unique in that they are split into between seven and nine horny plates. They produce astomach oil made up ofwax esters andtriglycerides that is stored in theproventriculus. This can be sprayed out of their mouths as a defence against predators and used as an energy rich food source for chicks and for the adults during their long flights.[18] Above the nasal passage they have asalt gland, which helps to remove salt from their blood; this salt, primarily sodium chloride, is in their marine invertebrate food and in the large amount of ocean water that they imbibe; it excretes a concentrated salt solution from the nostrils.[19]
The range of this bird is quite large as it ranges from Antarctica to thesubtropics of Chile, Africa, and Australia,[16][20] Itbreeds on numerous islands throughout the southern oceans. The islands with larger populations include theFoveaux Strait, Falkland Islands,South Georgia, South Orkney Islands,Staten Island, South Shetland,Heard Island, Macquarie Island, thePrince Edward Islands, and the Crozet Islands. The other locations with small populations are theKerguelen Islands, Gough Island,Tristan da Cunha, Diego Ramirez,Isla Noir as well as four locations on the continent of Antarctica, includingTerre Adélie, and small islands off the coast of Argentina nearChubut Province.[14] The colonies are visited year round.[16]
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The southern giant petrel achievessexual maturity at six or seven years of age; however the average age of first breeding is ten years.[14] Its breeding season begins in mid-October.[21][10] Its nest is a mound of moss, grass, and stones with a depression in the centre and is located on bare or grassy ground.[16][22] They form widely dispersedcolonies around July–August through to September with the exception of theFalkland Islands where the colonies are much larger.[14]
One immaculate white egg that is 103 by 70 millimetres (4.1 by 2.8 in) is laid. It isincubated for 55–66 days, where it is always guarded by at least one of the parents.[23]
[24] When the white chick is born it isbrooded for two to three weeks and itfledges at 104–132 days.[16][25] The chicks are vulnerable to introduced mammalian predators like small rodents. These are generally not recognised as threats by the members of a colony, and thus can kill many chicks.[23][21]
The southern giant petrel will feed on fish,krill,squid,offal, and waste from vessels in coastal andpelagic waters, where they often follow fishing boats and cruise ships. Unlike most otherProcellariiformes, the southern giant petrel will eatcarrion.[16][14] The southern giant petrel is an extremely aggressive predator and will kill otherseabirds.[26][22] It has been seen preying on the adultAustralasian gannet by holding it underwater and drowning it. These birds have also been observed drowning yellow-nosed andblack-browed albatrosses.[27]The males exclude females from the carcasses that they are feeding on.[16]
| Location | Population | Date | Trend |
|---|---|---|---|
| Falkland Islands | 19,500 pairs | 2005 | Increasing |
| South Georgia | 5,500 pairs | 2006 | Increasing |
| South Shetland | 5,400 pairs | 2006 | Increasing |
| South Orkney Islands | 3,350 pairs | 2006 | Increasing |
| Heard Island and McDonald Islands | 2,500 pairs | 2005 | Decreasing |
| South America (Isla Noir, Diego Ramirez,Staten Island, Patagonia, islands offChubut,Argentina) | 2,300 pairs | 2006 | |
| Macquarie Island | 2,145 pairs | 2005 | Decreasing |
| Prince Edward Islands | 1,800 pairs | ||
| South Sandwich Islands | 1,550 pairs | 2006 | Increasing |
| Antarctic Peninsula | 1,190 pairs | Decreasing | |
| Crozet Islands | 1,060 pairs | Increasing | |
| Antarctic Continent (Terre Adélie) | 280 pairs | 2006 | Decreasing |
| Tristan da Cunha Islands | 230 pairs | 2004 | Increasing |
| Kerguelen Islands | 4 pairs | Increasing | |
| Gough Island | 1+ pairs | Increasing | |
| Total | 97,000 | 2007 | Decreasing 1%–9% per 10 yr/Increasing now |
In 2009, the southern giant petrel was upgraded to a status ofleast-concern fromnear-threatened by theIUCN.[1] Overall population trends show that in the 1980s there were 38,000 pairs which dropped to 31,000 in the late 1990s followed by 46,800 presently. TheFalkland Islands and most of theSouth Georgia Archipelago have shown increases from the 1980s to the present.[28]Terre Adélie has shown a drastic reduction as the count fell to 10–15 pairs from 80 pairs in the 1980s. The official generation trend listed byBirdLife International is a 1%–9% decline, but it is stated that this is a conservative number. Furthermore, they elaborate that a best case scenario puts it at a 17% increase and a worst-case scenario of a 7.2% reduction.[1][14]
Accidental deaths fromlongline fishing as well astrawl fishing near theFalkland Islands have posed a major threat to the species. Between 2,000 and 4,000 southern giant petrels were killed in 1997–1998 due to illegal longline fishing. Additionally, the number ofsouthern elephant seals, which is an important source ofcarrion, has been diminishing.[14]
To assist in the southern giant petrel's continued survival, it was listed inCMS Appendix II andACAP Annex I. Many of the islands that it breeds on arenature reserves, and Gough Island andMacquarie Island are World Heritage Sites. Monitoring is done onSouth Georgia, Marion Island, theCrozet Islands, Terre Adélie, andMacquarie Island. Gough Island has had two censuses in the last decade.[14]
Continued monitoring and surveys at major breeding sites have been proposed, as well as researching movement andmigration. Additionally, continued promotion of "best-practice mitigation measures" via existing methods outlined inCCAMLR, CMS, andFAO have also been proposed.[14]
