176
B. STONEHOUSE
a. Weight
Most penguins achieve their greatest weights just before moulting, and
suffer their greatest percentage losses during the moult. This is always
a period of fasting, and lasts from two weeks in the smaller to four or
five weeks in the larger species. Richdale (1954, p. 174) tabulates weight
losses of 37-45y0 during moult in King, AdBlie, Rockhopper, Yellow-eyed
and Little Blue penguins.
Polar and some sub-polar species suffer weight losses during breeding;
both sexes fast during courtship (when the colonies may be 50-60 miles
from open water) and males continue their fast during the first incubation
watch. Between April and August in Terre AdBlie, mean weights of male
Emperors fell during courtship (five weeks) and incubation (nine weeks)
from 36.7 kg to 24.7 kg, a loss of 33%. The weight of one male fell from
42.3 kg to 21.4 kg (49%) in 20 weeks, which included some enforced
captivity (PrBvost, 1961, pp. 37-38). Male Addie penguins of average
weight 5.4 kg, fasting during breeding in October and November at
Cape Royds, their southernmost breeding ground, lost 15% of body
weight during 11 days’ courtship and a further 8% during the subsequent
incubation watch of eight days (Stonehouse, 1964, p. 773, and in press].
Addies nearer the northern edge of their range a t Hope Bay, where air
temperatures are higher but sea ice usually persists longer in spring,
lost 30% of body weight in 35-40 days of courtship and incubation (data
from Sladen, 1958, pp. 53-54) - a lower rate than at Cape Royds (see
discussion p. 187 below). On South Georgia, female King penguins of
mean initial weight 14.3 kg lost about 25% during 2-24 weeks’ courtship
(including laying); males starting 1.7 kg heavier lost 33-40y0 during five
weeks’ courtship and incubation (Stonehouse, 1960, pp. 24,34,39). Long
fasting is not confined to the larger species of penguins. On Macquarie
Island Rockhopper females take the first incubation watch, fasting for
a total of 33-45 days (mean 39), probably from an original weight of a
little over 3 kg (data from Warham, 1963).
Weight can be added rapidly; Kings recovered from post-moulting to
pre-courting weights (average 9-5-15 kg) in 10 days, during late spring
when food was plentiful. The recovery took from 15 to 20 days in early
spring before the main flush of food appeared in surface waters (Stonehouse, 1960, p. 24). AdBlies added 1 kg (20%) to their body weight in
3-4 days during their first spell a t sea after courtship and incubation
(Stonehouse, unpublished data). A Yellow-eyed penguin increased in
weight from 3-25 to 5.5 kg in 15 days (Richdale, 1957, p. 173).
Normal gains and losses of weight in courtship and incubation may
involve only fat stores: heavier losses during moult reflect mobilization
of protein for keratin production, and probably severe energy losses due
to the exposure of heavily vascularized skin. Dehydration does not
B. STONEHOUSE
a. Weight
Most penguins achieve their greatest weights just before moulting, and
suffer their greatest percentage losses during the moult. This is always
a period of fasting, and lasts from two weeks in the smaller to four or
five weeks in the larger species. Richdale (1954, p. 174) tabulates weight
losses of 37-45y0 during moult in King, AdBlie, Rockhopper, Yellow-eyed
and Little Blue penguins.
Polar and some sub-polar species suffer weight losses during breeding;
both sexes fast during courtship (when the colonies may be 50-60 miles
from open water) and males continue their fast during the first incubation
watch. Between April and August in Terre AdBlie, mean weights of male
Emperors fell during courtship (five weeks) and incubation (nine weeks)
from 36.7 kg to 24.7 kg, a loss of 33%. The weight of one male fell from
42.3 kg to 21.4 kg (49%) in 20 weeks, which included some enforced
captivity (PrBvost, 1961, pp. 37-38). Male Addie penguins of average
weight 5.4 kg, fasting during breeding in October and November at
Cape Royds, their southernmost breeding ground, lost 15% of body
weight during 11 days’ courtship and a further 8% during the subsequent
incubation watch of eight days (Stonehouse, 1964, p. 773, and in press].
Addies nearer the northern edge of their range a t Hope Bay, where air
temperatures are higher but sea ice usually persists longer in spring,
lost 30% of body weight in 35-40 days of courtship and incubation (data
from Sladen, 1958, pp. 53-54) - a lower rate than at Cape Royds (see
discussion p. 187 below). On South Georgia, female King penguins of
mean initial weight 14.3 kg lost about 25% during 2-24 weeks’ courtship
(including laying); males starting 1.7 kg heavier lost 33-40y0 during five
weeks’ courtship and incubation (Stonehouse, 1960, pp. 24,34,39). Long
fasting is not confined to the larger species of penguins. On Macquarie
Island Rockhopper females take the first incubation watch, fasting for
a total of 33-45 days (mean 39), probably from an original weight of a
little over 3 kg (data from Warham, 1963).
Weight can be added rapidly; Kings recovered from post-moulting to
pre-courting weights (average 9-5-15 kg) in 10 days, during late spring
when food was plentiful. The recovery took from 15 to 20 days in early
spring before the main flush of food appeared in surface waters (Stonehouse, 1960, p. 24). AdBlies added 1 kg (20%) to their body weight in
3-4 days during their first spell a t sea after courtship and incubation
(Stonehouse, unpublished data). A Yellow-eyed penguin increased in
weight from 3-25 to 5.5 kg in 15 days (Richdale, 1957, p. 173).
Normal gains and losses of weight in courtship and incubation may
involve only fat stores: heavier losses during moult reflect mobilization
of protein for keratin production, and probably severe energy losses due
to the exposure of heavily vascularized skin. Dehydration does not