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Studies in numerous animal taxa demonstrate that early rearing experience has a profound influence on the development of later adaptive behavior. This has implications for endangered species management, particularly when animals are reared in captivity for reintroduction or in cases in which species managers play an active role in managing animals at the individual or population levels. The California condor (Gymnogyps californianus) is a critically endangered New World vulture that was subject to a period of extinction in the wild followed by ongoing reintroduction in portions of its native range. Though the reintroduced population in southern California is largely adapting well, several obstacles to viability remain that are primarily anthropogenic in nature. The purpose of this study was to quantitatively assess nesting behavior of free-flying California condors in the southern California population to determine whether differences in parental care and nestling behavior are attributable to parental rearing conditions and experience. Hierarchical generalized linear modeling was used to analyze parent and chick activity budget data. Differences among condors were not detected in attendance patterns across either the egg or chick phases of nesting. Variation was not detected among chicks in proportion of time spent active and inactive during the early nestling phase. Variations among older nestlings in the proportion of time spent inactive were observed, with associations detected between inactivity, pair, visibility and season. The proportion of time that parents interacted with nestlings varied from nest to nest, with associations detected between interaction, visibility and season. Finally, potential pair-level variation in the propensity to bring microtrash to the nest was observed. It is concluded that while visibility is often overlooked in behavioral analyses, it is methodologically important to account for this variable in analyses of condor nestling behavior. Further, while some pair-level variation in allocation of care to nestlings is apparent, this appears to be a function of factors not related to individual developmental differences. |
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