Parental care promotes the survival and well-being of the offspring, and species, at a cost of resources to the parents as well as the apparently sacrificial acts of individual parents. This important vertebrate behavior is the most obvious and pervasive example of altruism in the kingdom Animalia representing the original form of prosocial behavior from which all other animal behaviors are presumed to be derived. The period between birth/hatching and recruitment into a breeding population is a critical phase and may be considered one of the least understood components of animal life histories. The survival of the young until reproduction has marked effects on population growth and is more sensitive to environmental changes than adult survival.