Cape Crozier is located at the eastern extremity of Ross Island, southern Ross Sea, where the Ross Ice Shelf pushes up against the land at Cape Crozier and forms large pressure cracks in the shelf ice near its seaward terminus. Fast ice forms between the cracks, providing habitat suitable for breeding Emperor Penguins (Aptenodytes forsteri). The IBA qualifies, however, on the basis of the large Adélie Penguin (Pygoscelis adeliae) and South Polar Skua (Catharacta maccormicki) colonies that occupy ice free slopes on the coastline north of Cape Crozier. The IBA boundary is coincident with that of Antarctic Specially Protected Area No. 124: Cape Crozier, Ross Island. The area lies at the foot of the mainly ice-free northeastern slopes of Mount Terror (3230 m). The geology is of volcanic origin, with slopes interspersed by small cones and craters of scoria and basalts. Sparse growth of various species of algae, mosses and lichens occurs across the area. Recent meteorological records from ~35 km to the east recorded December as the warmest month with a mean temperature of -5.8°C, and August the coldest with a mean temperature of -33.1°C. A small field hut (USA) is located close to the northwestern boundary of the protected area. The nearest permanent scientific stations are Scott Base (NZL) and McMurdo (USA), situated ~80 km to the southwest on Hut Point Peninsula, Ross Island.
One of the largest Adélie Penguin colonies in Antarctica is located on the coast ~5 km north of Cape Crozier. This is divided into two colonies, commonly referred to as ‘East' and ‘West', which are separated by ~1 km and a prominent ridge and icefield. Over the last 50 years the colony has substantially grown, from ~65 000 breeding pairs in 1958 to ~272 340 breeding pairs in 2012 (Lyver et al. 2014). However several large icebergs situated in the foraging area from 2001-05 had a significant negative influence on bird breeding performance. An Emperor Penguin colony of 1189 pairs (2012 estimate) breeds on fast ice that forms in the cracks in the Ross Ice Shelf near Cape Crozier (G. Kooyman pers. comm. 2014). The location of the breeding site varies from season to season. South Polar Skuas breed on ice-free ground surrounding the Adélie colonies, and comprised ~1000 breeding pairs in the 1960s / 70s. More recently, Wilson et al . (in prep.) estimated 1361 and 1108 breeding pairs in 2011/12 and 2012/13, respectively. This represents the largest South Polar Skua colony documented in Antarctica. Several other bird species have been recorded as non-breeding visitors to Cape Crozier, including Chinstrap Penguins ( Pygoscelis antarctica ), Wilson's Storm-petrels ( Oceanites oceanicus ), Snow Petrels ( Pagodroma nivea ), Antarctic Petrels ( Thalassoica antarctica ), Southern Fulmars ( Fulmarus glacialoides ), Southern Giant Petrels ( Macronectes giganteus ), and Kelp Gulls ( Larus dominicanus ). Non-bird biodiversity: Weddell Seals (Leptonychotes weddellii) have been recorded breeding in the vicinity. Leopard Seals (Leptonyx hydrurga) and Crabeater Seals (Lobodon carcinophagus) have also been observed. Several distinct types of Killer Whales (Orcinus orca) regularly forage nearby.
Pressure/threats to key biodiversity
The principal reason for designation of Cape Crozier as a protected area in 1966 was on the grounds that it supports a rich bird and mammal fauna, microfauna and microflora. Long-term studies of the population dynamics and social behaviour of emperor and Adélie Penguins are also reasons for protection. The Management Plan for ASPA No. 124 provides strict rules to govern the conduct of any visits to the area. Access to the area by aircraft has potential to disturb the large colonies of breeding birds, although the management plan provides strict guidance on routes, overflight and landing sites. In 2001, the giant iceberg B15A collided with the Ross Ice Shelf near Cape Crozier and indirectly caused a total breeding failure among the Emperor Penguins that frequent the site (Kooyman et al. 2007). In following years, while B15A was still present, access to the Ross Sea polynya was limited and the breeding success of the Cape Crozier colony ranged from 0-40% of that in 2000. Calving events occur regularly in Antarctica, although a significant increase in their frequency may have substantial consequences for Emperor penguins, and possibly other animals. Concerns have been expressed about changes to the Ross Sea ecosystem as a result of the Antarctic Toothfish (Dissostichus mawsoni) fishery, which may be contributing to an increase in regional Adélie Penguin populations and a decline and/or shift in their predator species (Lyver et al. 2014).
BirdLife International (2023) Important Bird Areas factsheet: Cape Crozier, Ross Island. Downloaded from
http://www.birdlife.org on 04/02/2023.