1G2
B. STONEHOUSE
r n
D Uruauovon 1
I 1 1 1 1 1 1 1 1 1 1 1 I I I I I
N
F
M
A
N
F
FIQ. 9. Annual sea temperature ranges for the Uruguayan coast and Valdez Peninsula.
Autumn and spring migrations allow Magellanic penguins to remain within a comparatively narrow temperature range throughout the year. N, F, M, A = November, February, May, August.
returning to their breeding grounds in September and October. They
leave the breeding areas in April, but whether to the warm waters north
of La Plata (giving a total annual range of 6°C) or to some cooler intermediate area more appropriate to a southern stock, is at present unknown. On Mocha Island, Chile, toward the northern edge of the species'
breeding range, mean summer and winter temperatures are respectively
17°C and 13°C; local Magellanic penguins are resident throughout the
year, and would almost certainly be distinguishable from more southerly
stocks in some aspect of their heat regulating mechanisms.
Environmental temperatures - terrestrial, aquatic, or both -- are
responsible for the development of subspecific characters in a t least one
species of penguin. Gentoos of the Antarctic Peninsula, breeding a t the
southern edge of the species' range and feeding among pack ice, probably
winter close to their breeding grounds (Bagshawe, 1938, pp. 226-227) and
may never experience sea water temperatures higher than + 1 - + 2°C.
Gentoos on the Falkland Islands are also resident (Cawkell and
Hamilton, 1961, p. 5), living in an annual sea water temperature range
of 5-9°C. Murphy (1947, p. 464) distinguished the southern form as a
separate subspecies with smaller extremities: they are also shorter and
lighter than northern birds, with longer plumage and with flippers considerably smaller in area (Stonehouse, in press; see table I). Gentoos of
Macquarie Island seem to be intermediate in size, proportions and plumage length, supporting the rather inadequate grounds on which they
were earlier given subspecific status. I am investigating similar differences in Macaroni, Rockhopper and Magellanic penguins, and would
B. STONEHOUSE
r n
D Uruauovon 1
I 1 1 1 1 1 1 1 1 1 1 1 I I I I I
N
F
M
A
N
F
FIQ. 9. Annual sea temperature ranges for the Uruguayan coast and Valdez Peninsula.
Autumn and spring migrations allow Magellanic penguins to remain within a comparatively narrow temperature range throughout the year. N, F, M, A = November, February, May, August.
returning to their breeding grounds in September and October. They
leave the breeding areas in April, but whether to the warm waters north
of La Plata (giving a total annual range of 6°C) or to some cooler intermediate area more appropriate to a southern stock, is at present unknown. On Mocha Island, Chile, toward the northern edge of the species'
breeding range, mean summer and winter temperatures are respectively
17°C and 13°C; local Magellanic penguins are resident throughout the
year, and would almost certainly be distinguishable from more southerly
stocks in some aspect of their heat regulating mechanisms.
Environmental temperatures - terrestrial, aquatic, or both -- are
responsible for the development of subspecific characters in a t least one
species of penguin. Gentoos of the Antarctic Peninsula, breeding a t the
southern edge of the species' range and feeding among pack ice, probably
winter close to their breeding grounds (Bagshawe, 1938, pp. 226-227) and
may never experience sea water temperatures higher than + 1 - + 2°C.
Gentoos on the Falkland Islands are also resident (Cawkell and
Hamilton, 1961, p. 5), living in an annual sea water temperature range
of 5-9°C. Murphy (1947, p. 464) distinguished the southern form as a
separate subspecies with smaller extremities: they are also shorter and
lighter than northern birds, with longer plumage and with flippers considerably smaller in area (Stonehouse, in press; see table I). Gentoos of
Macquarie Island seem to be intermediate in size, proportions and plumage length, supporting the rather inadequate grounds on which they
were earlier given subspecific status. I am investigating similar differences in Macaroni, Rockhopper and Magellanic penguins, and would