We examined variation in meal size, feeding frequency and daily food delivery in relation to age, nest, day, year, and weather by White-tailed Tropicbirds (Phaethon lepturus) using repeated weighing of chicks. We focused particularly on the differences between chicks which survived and those which died. Unsuccessful chicks became significantly lighter than successful chicks at the age of 30 days; however, some were fed until they were 60 days old. Feeding frequency and meal size differed significantly between both age classes and between surviving and nonsurviving chicks. In surviving chicks, feeding frequency remained relatively constant until chicks reached 60 days and dropped progressively thereafter. In this group, meal size was significantly lower in chicks up to 20 days old and over 70 days old than those aged 21–70 days. We found significant relationships between chick food provisioning and day, nest, and year. Feeding frequency was more important than meal size in explaining the difference in food delivery between surviving and nonsurviving chicks. This was due to much greater significant differences for feeding frequency than for meal size between surviving and nonsurviving chicks, including annual differences in feeding frequency (but not in meal size) for surviving chicks. Our study suggests that parents of unsuccessful chicks had difficulty in obtaining sufficient food for their chicks from very early on, but responded to this problem first by decreasing the feeding frequency and, later, decreasing both feeding frequency and meal size. Our study shows that parents vary in their abilities to provide optimal provisioning to their chicks. Environmental conditions determine further energetic constraints in food delivery to chicks.