Provisioning Behaviour in a Communal Breeder: an Epigenetic Approach To the Study of Individual Variation in Behaviour

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Abstract
This study used an epigenetic approach to examine the development of individual variation in provisioning behaviour in a communally breeding bird, the pukeko. Breeders who are initially 'exposed' to chicks during incubation were the first to brood and provision newly hatched chicks. From the first week after hatching until midway through the provisioning period, there was no significant difference in the percentage of time spent provisioning by breeders and non-breeders suggesting that the maintenance of provisioning is not dependent on increases in hormone levels attained through breeding or incubation, but on stimulations that arise through contact with the chicks. Breeders reduced and eventually stopped provisioning chicks midway through the provisioning period in association with the laying of a second clutch. Social learning, imitation and the 'priming' effect of other behaviours appeared to influence the onset of provisioning in inexperienced or naive juvenile and yearling pukeko. Inexperienced birds initially exhibited a heightened response toward hatchlings which appears to be the result of some sort of novelty effect. Inexperienced yearlings, however, did not provision for as long into the season as experienced non-breeders unless the latter were not present in the group or had stopped provisioning earlier in the season. It is proposed that factors giving rise to and maintaining behavioural asymmetries can best be understood from an epigenetic perspective. This study used an epigenetic approach to examine the development of individual variation in provisioning behaviour in a communally breeding bird, the pukeko. Breeders who are initially 'exposed' to chicks during incubation were the first to brood and provision newly hatched chicks. From the first week after hatching until midway through the provisioning period, there was no significant difference in the percentage of time spent provisioning by breeders and non-breeders suggesting that the maintenance of provisioning is not dependent on increases in hormone levels attained through breeding or incubation, but on stimulations that arise through contact with the chicks. Breeders reduced and eventually stopped provisioning chicks midway through the provisioning period in association with the laying of a second clutch. Social learning, imitation and the 'priming' effect of other behaviours appeared to influence the onset of provisioning in inexperienced or naive juvenile and yearling pukeko. Inexperienced birds initially exhibited a heightened response toward hatchlings which appears to be the result of some sort of novelty effect. Inexperienced yearlings, however, did not provision for as long into the season as experienced non-breeders unless the latter were not present in the group or had stopped provisioning earlier in the season. It is proposed that factors giving rise to and maintaining behavioural asymmetries can best be understood from an epigenetic perspective.