134
B. STONEHOUSE
apterylous and waterproof, and heavy subcutaneous fat, combine to
give penguins their characteristic form and gait. They answer the
two important aquatic requirements of ( a ) swimming efficiency (without
loss of mobility on land) and (b) efficient thermal insulation. Otariid
seals, which are in many ways mammalian counterparts of penguins,
have several closely analogous adaptations.
Anatomical characters distinguishing species - even polar from
tropical species - are trivial in comparison. Except for size, most of the
specific and generic characters are borne on the head, where they are
visible in birds resting on the surface (Wilson, 1907, p. 36; Murphy,
1936, 1’. 334) and probably interfere least with the thermal qualities of
the plumage. Size distinguishes only two genera (Apteizodytes and
Eudyptula, the largest and smallest): two-thirds of the species fall within
the 3-6 kg range and can barely be distinguished on size alone. Some
differences in plumage structure and thickness between polar and tropical
species have recently been described (Stonehouse, in press); other
differences, e.g. in proportions of extremities, conform to ecological expectation in some but not all genera. However, the family as a whole
has a stamp of uniformity, largely a product of the marine environment,
which a wide diversity of terrestrial habitats has barely modified.
The following terminology is used in this study.
( a ) Species. Peters’ checklist (1932, p. 29-33) catalogues 17 species and
nine subspecies of penguins, in six genera. My list differs in (i) excluding
two subspecies Aptenodytes patagonica halli and Eudyptes crestatusfilholi
which do not appear to have received critical support since their original
citations and for which I can provide no new evidence, (ii) omitting the
subspecies of Eudyptes crestatus, for which I have no separate information
at present, (iii) including Murphy’s Pygoscelis papua ellsworthii ( 1047,
p. 454), one of the few penguin Subspecies for which adequate evidence
has been provided, and Eudyptes robustus, a species proposed by Oliver
(1053, p. 187); for these last two I have provided additional data based
on flipper and plumage measurements (Stonehouse, in press). , 4 full
taxonomic review of the penguins, especially of the controversial and
interesting genera Eudyptes and Eudyptula, is long overdue.
(b) Biogeographic zones. Different systems of classifying biogeographic
zones have been devised by shore ecologists, botanists, planktologists,
fish and bird systematists and others (Murphy, 1936; Deacon, 1937; see
also separate contributions in Pantin, 1960; and Van Meighen, Van Oye
and Schell, 1965). All regard the sub-antarctic and sub-tropical convergences as important biogeographical boundaries (Fig. 1) ; the significance
of the northern limit of pack ice for land flora and fauna in the far south
has also been stressed (Stonehouse, 1965, p. 162). Penguin distribution
does not conform exactly to any of the published systems of nomenclature,
B. STONEHOUSE
apterylous and waterproof, and heavy subcutaneous fat, combine to
give penguins their characteristic form and gait. They answer the
two important aquatic requirements of ( a ) swimming efficiency (without
loss of mobility on land) and (b) efficient thermal insulation. Otariid
seals, which are in many ways mammalian counterparts of penguins,
have several closely analogous adaptations.
Anatomical characters distinguishing species - even polar from
tropical species - are trivial in comparison. Except for size, most of the
specific and generic characters are borne on the head, where they are
visible in birds resting on the surface (Wilson, 1907, p. 36; Murphy,
1936, 1’. 334) and probably interfere least with the thermal qualities of
the plumage. Size distinguishes only two genera (Apteizodytes and
Eudyptula, the largest and smallest): two-thirds of the species fall within
the 3-6 kg range and can barely be distinguished on size alone. Some
differences in plumage structure and thickness between polar and tropical
species have recently been described (Stonehouse, in press); other
differences, e.g. in proportions of extremities, conform to ecological expectation in some but not all genera. However, the family as a whole
has a stamp of uniformity, largely a product of the marine environment,
which a wide diversity of terrestrial habitats has barely modified.
The following terminology is used in this study.
( a ) Species. Peters’ checklist (1932, p. 29-33) catalogues 17 species and
nine subspecies of penguins, in six genera. My list differs in (i) excluding
two subspecies Aptenodytes patagonica halli and Eudyptes crestatusfilholi
which do not appear to have received critical support since their original
citations and for which I can provide no new evidence, (ii) omitting the
subspecies of Eudyptes crestatus, for which I have no separate information
at present, (iii) including Murphy’s Pygoscelis papua ellsworthii ( 1047,
p. 454), one of the few penguin Subspecies for which adequate evidence
has been provided, and Eudyptes robustus, a species proposed by Oliver
(1053, p. 187); for these last two I have provided additional data based
on flipper and plumage measurements (Stonehouse, in press). , 4 full
taxonomic review of the penguins, especially of the controversial and
interesting genera Eudyptes and Eudyptula, is long overdue.
(b) Biogeographic zones. Different systems of classifying biogeographic
zones have been devised by shore ecologists, botanists, planktologists,
fish and bird systematists and others (Murphy, 1936; Deacon, 1937; see
also separate contributions in Pantin, 1960; and Van Meighen, Van Oye
and Schell, 1965). All regard the sub-antarctic and sub-tropical convergences as important biogeographical boundaries (Fig. 1) ; the significance
of the northern limit of pack ice for land flora and fauna in the far south
has also been stressed (Stonehouse, 1965, p. 162). Penguin distribution
does not conform exactly to any of the published systems of nomenclature,