Simple Summary: Grey-faced Petrels breed on islands around the upper North Island of New Zealand and raise one chick per year from September to December. Parents forage at sea and return to the colony intermittently to feed chicks. We monitored the feeding rate of chicks every 12 h for 10 consecutive days in 2011 and 2013 at the colony on Te Hāwere-a-Maki (Goat Island). In both years tropical Pacific Ocean winds bringing warmer surface air temperatures made raising chicks more difficult for parents. We found chicks processed their meals during the day and conserved energy from five days after their last meal, not knowing when their next meal might arrive. Body mass loss after meals did not depend on chick age nor body mass, but heavier chicks were more likely to survive. Measurements of feeding rates of chicks that were not included in our study showed no negative effect of our intensive monitoring on feeding rates of chicks in our study. Chicks being fed on average 100-gram meals every 10 days from each parent is unlikely to sustain them. Grey-faced Petrels (Pterodroma gouldi) are colonial burrowing seabirds predominantly nesting on offshore islands of the upper North Island of New Zealand. We studied their chick provisioning on Te Hāwere-a-Maki during two years of unfavourable warmer La Niña conditions in 2011 and 2013. We intensively monitored chicks in each year, weighing chicks every 12 h for 10 consecutive days to estimate meal sizes following chick provisioning and to estimate 12-hourly body mass loss as a function of time since last feeding. We found a quadratic relationship of body mass loss with time since last feeding, with rapid digestion of meals following provisioning followed by a period of fasting from five days post feeding as chicks waited an unknown and variable amount of time until their next meal. The rate of body mass loss did not depend on chick age nor body mass, and did not differ between years, but heavier chicks included in our study were more likely to successfully fledge, suggesting a legacy of adult provisioning prior to our study commencing. Our regular handling of chicks for monitoring has no discernible impact on parent provisioning compared to a set of control chicks. The mean estimates of 100-gram meal sizes and 10-day foraging trip durations are likely to be below the break-even point for this species. [ABSTRACT FROM AUTHOR]