Aspects of chick-provisioning in Wilson's Storm-Petrel were measured a
t Palmer Station, Antarctica. Chicks received meals averaging 9.2 g (2
1% of adult body mass) with a mean frequency of 1.1 feeds/chick.day. F
eeding frequency decreased as chicks grew, but meal mass remained rela
tively constant throughout the fledging period. Free lipids accounted
for an average of 24% of the mass and over 60% of the energy in a meal
. The energy density of the meals averaged 16.1 kJ/g, nearly triple th
at of whole prey. The estimated rates at which gross and metabolizable
energy were delivered to the chick averaged 163 and 147 kJ/days, resp
ectively, over the 60 day fledging period. Low nest temperatures resul
ted in high energy requirements by the chicks. Rates of respiratory en
ergy metabolism averaged 133 kJ/day over the hedging period and reache
d peak levels of similar to 160 kJ/day. Rates of energy deposition in
tissues averaged only 18.4 kJ/day day with a peak rate of similar to 5
7 kJ/day. Thus, total metabolizable energy requirements of the chick a
veraged 151 kJ/day, which is within 3% of estimated metabolizable ener
gy intake. Wilson's Storm-Petrel chicks have energy requirements nearl
y double those of Leach's Storm-Petrel chicks which grow in a more tem
perate climate. Wilson's Storm-Petrel adults appear to meet demands of
their chicks with a high frequency of meal delivery and high energy d
ensity of meals compared to those of Leach's Storm-Petrel. A compariso
n of the rates of energy utilization by foraging adults of the two spe
cies suggests that the high energy demands of the Wilson's Storm-Petre
l chicks have selected for a foraging strategy in adult Wilson's Storm
-Petrels that is expensive in terms of energy and time. Low air temper
atures, a short summer season, and the presence of diurnal predators o
n the breeding grounds are among the factors which have shaped the chi
ck-provisioning strategy of this species. The data suggest that Wilson
's Storm-Petrels could not breed successfully in the Antarctic without
the ability to produce stomach oils.