THE GENERAL BIOLOGY O F PENGUINS
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has very large populations of Rockhoppers and Royal penguins, and
smaller numbers of breeding Gentoos and Kings.
f. Sub-Antarctic islands
South Georgia and Heard Islands, lying between the Antarctic convergence and the northern limit of pack ice, are high and heavily
glaciated; Kerguelen, lying athwart the convergence, has less permanent
ice and a more gentle maritime climate (Figs. 7 and 8).
Iles Kerguelen form a closely-knit group; the main island, over 200
miles (320 km) long, has a deeply indented coastline providing miles of
sheltered waterways and a rich variety of bird habitats. 81 % of recorded
winds are from northwest-southwest sector (Fabricius, 1957, p. 120).
Coastal vegetation consists mainly of tussock grass and herbfield communities, well browsed by rabbits. Penguins are plentiful “. . . but not
in proportion to the nesting areas available, at any rate in Royal Sound”
(Falla, 1937, p. 14). Wild dogs and cats, and the earlier depredations of
oil hunters, may have reduced the original stocks. King, Gentoo and
Rockhopper penguins breed in quantity; Macaronis are less numerous,
but breed both in large colonies of their own and among Rockhoppers
(Murphy, 1936, p. 435; Paulian, 1953, p. 145).
South Georgia. About 100 miles (160 km) long and up to 20 miles
(32 km) across, South Georgia is the largest of the island habitats yet
considered. Its highest peak rises over 9 000 ft (2 800 m), forming the
main massif of an alpine chain along the backbone of the island; the
shores are narrow or precipitous, intersected with glacier faces. Fringing
raised beaches provide nesting sites for many seabirds. The northern
edge of pack ice is sometimes visible from the shore in winter; the
southern side of the island, facing the Weddell Sea, is distinctly less
hospitable than the northern side. Sea temperatures range from slightly
below freezing point to 3-4°C above; fast ice forms temporarily in
sheltered bays in winter. Air temperatures shift rapidly with wind
changes, cold air from the island’s own icefields being felt occasionally
on the coast in summer. Snow lies at sea level for 7-10 months annually.
Gentoo and Macaroni penguins nest among tussock, respectively on
gently rising ground and on steeper boulder slopes; some gentoos nest
neatly on tussock heads, well above the morasse which forms around
them during the spring thaw. King penguins are plentiful, concentrated
in seven breeding colonies on the northern side of the island (Stonehouse,
1960, p. 6). Chinstrap penguins, for long considered marginal breeders
on South Georgia, have recently increased in numbers (Stonehouse, in
press). For a general account and census of South Georgia penguins see
Rankin, 1951.
Heard Island is roughly 27 miles (43 km) long and 13 miles (21 km)
153
has very large populations of Rockhoppers and Royal penguins, and
smaller numbers of breeding Gentoos and Kings.
f. Sub-Antarctic islands
South Georgia and Heard Islands, lying between the Antarctic convergence and the northern limit of pack ice, are high and heavily
glaciated; Kerguelen, lying athwart the convergence, has less permanent
ice and a more gentle maritime climate (Figs. 7 and 8).
Iles Kerguelen form a closely-knit group; the main island, over 200
miles (320 km) long, has a deeply indented coastline providing miles of
sheltered waterways and a rich variety of bird habitats. 81 % of recorded
winds are from northwest-southwest sector (Fabricius, 1957, p. 120).
Coastal vegetation consists mainly of tussock grass and herbfield communities, well browsed by rabbits. Penguins are plentiful “. . . but not
in proportion to the nesting areas available, at any rate in Royal Sound”
(Falla, 1937, p. 14). Wild dogs and cats, and the earlier depredations of
oil hunters, may have reduced the original stocks. King, Gentoo and
Rockhopper penguins breed in quantity; Macaronis are less numerous,
but breed both in large colonies of their own and among Rockhoppers
(Murphy, 1936, p. 435; Paulian, 1953, p. 145).
South Georgia. About 100 miles (160 km) long and up to 20 miles
(32 km) across, South Georgia is the largest of the island habitats yet
considered. Its highest peak rises over 9 000 ft (2 800 m), forming the
main massif of an alpine chain along the backbone of the island; the
shores are narrow or precipitous, intersected with glacier faces. Fringing
raised beaches provide nesting sites for many seabirds. The northern
edge of pack ice is sometimes visible from the shore in winter; the
southern side of the island, facing the Weddell Sea, is distinctly less
hospitable than the northern side. Sea temperatures range from slightly
below freezing point to 3-4°C above; fast ice forms temporarily in
sheltered bays in winter. Air temperatures shift rapidly with wind
changes, cold air from the island’s own icefields being felt occasionally
on the coast in summer. Snow lies at sea level for 7-10 months annually.
Gentoo and Macaroni penguins nest among tussock, respectively on
gently rising ground and on steeper boulder slopes; some gentoos nest
neatly on tussock heads, well above the morasse which forms around
them during the spring thaw. King penguins are plentiful, concentrated
in seven breeding colonies on the northern side of the island (Stonehouse,
1960, p. 6). Chinstrap penguins, for long considered marginal breeders
on South Georgia, have recently increased in numbers (Stonehouse, in
press). For a general account and census of South Georgia penguins see
Rankin, 1951.
Heard Island is roughly 27 miles (43 km) long and 13 miles (21 km)