THE GENERAL BIOLOGY OF PENGUINS
173
111. MORPHOLOGY, METABOLISM AND HEAT BALANCE
A. FORM AND METABOLISM
1. Dimensions and Proportions
Weights and measurements of all recognized species and subspecies
of penguins are listed in Table I.
Weight is the most easily measured of all penguin dimensions and,
properly interpreted, the best single indicator of size differences between
species. However, weights of individuals vary widely, due to the birds’
capacity for storing visceral and subcutaneous fat (p. 176 below). Nean
weights in Table I are calculated from data in published and unpublished
sources, from which extreme values of pathologically thin birds and of
polar species in pre-moult fat were excluded to eliminate bias in the
rather small samples. Means therefore represent the weight of healthy
birds, neither moulting nor excessively fat, with empty crop. Weight
ranges in Table I incorporate all reliable adult values I have been able
to trace, including some pre-moult and post-moult weights but excluding
those of very thin birds known or believed to be dying. Means in brackets
are calculated from fewer than ten values; ranges partly or completely
bracketed indicate small samples in which one or both means are
suspect.
Linear dimensions are intrinsically less variable than weights in adult
birds, but are more subject to variation in technique. There is no recognized standard method of measuring feet or flippers, and many authors
have invalidated painstaking work by failing to specify the endpoints of
their measurements. In Table I all the dimensions of foot and flipper are
from my own measurements, recorded especially for a comparative study
by techniques illustrated in Stonehouse (1960, p. 10) from skins in
British, American and Australasian museums (see acknowledgments).
Although samples of fewer than 20 were obtained for some species, the
results are directly comparable with each other. Measurements of length
and girth are from published sources, field notes and museum labels;
their reliability is correspondingly lower.
Plumage length was measured by inserting the tip of a small steel ruler
among the feathers and extending the nearest feather along it by light
finger pressure (technique described more fully in a note now in press);
each specimen provided three dorsal and three ventral values from
which means were calculated.
Flipper areas were obtained by inserting a sheet of paper under the
flipper of a specimen, carefully drawing round it, and weighing the
resulting lamina against a standard sheet of paper. Values from live,
freshly dead, frozen, and dried museum specimens are directly comparable within the limits of accuracy of the technique.
173
111. MORPHOLOGY, METABOLISM AND HEAT BALANCE
A. FORM AND METABOLISM
1. Dimensions and Proportions
Weights and measurements of all recognized species and subspecies
of penguins are listed in Table I.
Weight is the most easily measured of all penguin dimensions and,
properly interpreted, the best single indicator of size differences between
species. However, weights of individuals vary widely, due to the birds’
capacity for storing visceral and subcutaneous fat (p. 176 below). Nean
weights in Table I are calculated from data in published and unpublished
sources, from which extreme values of pathologically thin birds and of
polar species in pre-moult fat were excluded to eliminate bias in the
rather small samples. Means therefore represent the weight of healthy
birds, neither moulting nor excessively fat, with empty crop. Weight
ranges in Table I incorporate all reliable adult values I have been able
to trace, including some pre-moult and post-moult weights but excluding
those of very thin birds known or believed to be dying. Means in brackets
are calculated from fewer than ten values; ranges partly or completely
bracketed indicate small samples in which one or both means are
suspect.
Linear dimensions are intrinsically less variable than weights in adult
birds, but are more subject to variation in technique. There is no recognized standard method of measuring feet or flippers, and many authors
have invalidated painstaking work by failing to specify the endpoints of
their measurements. In Table I all the dimensions of foot and flipper are
from my own measurements, recorded especially for a comparative study
by techniques illustrated in Stonehouse (1960, p. 10) from skins in
British, American and Australasian museums (see acknowledgments).
Although samples of fewer than 20 were obtained for some species, the
results are directly comparable with each other. Measurements of length
and girth are from published sources, field notes and museum labels;
their reliability is correspondingly lower.
Plumage length was measured by inserting the tip of a small steel ruler
among the feathers and extending the nearest feather along it by light
finger pressure (technique described more fully in a note now in press);
each specimen provided three dorsal and three ventral values from
which means were calculated.
Flipper areas were obtained by inserting a sheet of paper under the
flipper of a specimen, carefully drawing round it, and weighing the
resulting lamina against a standard sheet of paper. Values from live,
freshly dead, frozen, and dried museum specimens are directly comparable within the limits of accuracy of the technique.