THE GENERAL BIOLOGY OF PENGUINS
155
present even in summer. Addie and Chinstrap penguins are the most
numerous species, with fewer Macaronis and Gentoos. Food seems to be
extremely plentiful in summer, although its availability close to the
breeding grounds must vary from year to year with the extent of fast
ice and density of the local pack.
South Sandwich Islands form a chain of 11 volcanic peaks (some still
active) extending in an arc north and south between latitudes 56' and
60"s. Holdgate (1963, p. 402) describes them as conspicuously more
barren than the South Orkneys (although farther north); the southern
islands appear to have the severest climate, possibly resulting from their
longer annual investment in sea ice (Stonehouse, 1964, p. 228). King
penguins breed on the northernmost islands. AdBlie, Chinstrap, Gentoo
and Macaroni penguins have been recorded on several islands, including
the southernmost.
Bouwet~ya is roughly five miles (8 km) in diameter and almost entirely
ice-covered. The small area of flat ground available for nesting is endangered by avalanches and rock falls, and fur seals and elephant seals
compete with penguins for living space. Holgersen (1945, p. 85) and
Solyanik (1964, p. 98) list Macaronis, Chinstraps, and 12-20 pairs of
Adblies as the breeding penguins.
Peter I B y about 14 miles (22 km) long and five miles (8 km) wide, is
heavily glaciated at all but one point: here a group of 40-50 pairs of
Addies breed, together with a few pairs of Chinstraps (Holgersen, 1945,
p. 76, 1957). The island is usually surrounded by dense pack ice, and it
is difficult to determine whether the poor avifauna reflects lack of breeding space or unusually sparse food in nearby seas.
Scott Island less than half a mile (800 m) long and heavily ice-capped,
stands alone in the Ross Sea. Other species of sea birds have been
reported, but no penguins. It would be a likely site for an Emperor
penguin colony if winter fast ice is sufficiently firm.
Balleny Islands. Three large and two small islands, extending between
longitudes 162" and 165"E and crossing the Antarctic circle, form this
group; the largest is about 27 miles (43 km) long and rises to over 5 000 ft
(1 500 m). There are few areas of flat ground suitable for penguin colonization, but Sladen (1964, pp. 359, 362) reported a single large colony of
several thousand birds on Sabrina Islet, and five small colonies, one "a
mere handful of birds", in the Buckle-Sabrina Island area. Two pairs of
Chinstrap penguins holding nest sites suggested that the species may be
attempting to establish itself there.
h. Continental Antarctica
Much of the continental Antarctic coastline is hidden under the vast
covering ice sheet. Rocky coasts are found on the western side of the
155
present even in summer. Addie and Chinstrap penguins are the most
numerous species, with fewer Macaronis and Gentoos. Food seems to be
extremely plentiful in summer, although its availability close to the
breeding grounds must vary from year to year with the extent of fast
ice and density of the local pack.
South Sandwich Islands form a chain of 11 volcanic peaks (some still
active) extending in an arc north and south between latitudes 56' and
60"s. Holdgate (1963, p. 402) describes them as conspicuously more
barren than the South Orkneys (although farther north); the southern
islands appear to have the severest climate, possibly resulting from their
longer annual investment in sea ice (Stonehouse, 1964, p. 228). King
penguins breed on the northernmost islands. AdBlie, Chinstrap, Gentoo
and Macaroni penguins have been recorded on several islands, including
the southernmost.
Bouwet~ya is roughly five miles (8 km) in diameter and almost entirely
ice-covered. The small area of flat ground available for nesting is endangered by avalanches and rock falls, and fur seals and elephant seals
compete with penguins for living space. Holgersen (1945, p. 85) and
Solyanik (1964, p. 98) list Macaronis, Chinstraps, and 12-20 pairs of
Adblies as the breeding penguins.
Peter I B y about 14 miles (22 km) long and five miles (8 km) wide, is
heavily glaciated at all but one point: here a group of 40-50 pairs of
Addies breed, together with a few pairs of Chinstraps (Holgersen, 1945,
p. 76, 1957). The island is usually surrounded by dense pack ice, and it
is difficult to determine whether the poor avifauna reflects lack of breeding space or unusually sparse food in nearby seas.
Scott Island less than half a mile (800 m) long and heavily ice-capped,
stands alone in the Ross Sea. Other species of sea birds have been
reported, but no penguins. It would be a likely site for an Emperor
penguin colony if winter fast ice is sufficiently firm.
Balleny Islands. Three large and two small islands, extending between
longitudes 162" and 165"E and crossing the Antarctic circle, form this
group; the largest is about 27 miles (43 km) long and rises to over 5 000 ft
(1 500 m). There are few areas of flat ground suitable for penguin colonization, but Sladen (1964, pp. 359, 362) reported a single large colony of
several thousand birds on Sabrina Islet, and five small colonies, one "a
mere handful of birds", in the Buckle-Sabrina Island area. Two pairs of
Chinstrap penguins holding nest sites suggested that the species may be
attempting to establish itself there.
h. Continental Antarctica
Much of the continental Antarctic coastline is hidden under the vast
covering ice sheet. Rocky coasts are found on the western side of the