Breeding dispersal and parental care in blue tits (Cyanistes caeruleus)
Creators: name: Payne, Wesley
Publisher: name: Lancaster University
Year: 2018
Subjects: subject: Ecology
subject: FOS: Biological sciences
subject: Dispersal
subject: Blue tit
subject: Parental care
subject: Repeatability

description: Behaviour varies between individuals and is often thought to be adaptive.
      Behaviours are predicted to vary according to the circumstances of the
      individual, to decrease their risk of mortality or that of their
      offspring, or to reduce the costs associated with certain behaviours, such
      as territory establishment, foraging or nestling provisioning. Two of the
      most important behaviours determining reproductive success, and thus
      having potential to be adaptive, are breeding dispersal and parental care.
      Individual birds should be under selection pressure to minimise the costs
      related to these behaviours, and likely to do so in response to aspects of
      habitat quality, individual quality, and their own prior experience. This
      study examined the relative importance of these factors upon breeding
      dispersal and parental care in blue tits (Cyanistes caeruleus),
      additionally using repeatability analysis as a novel means to indirectly
      assess the influence of both individual quality and habitat.
      
      Specifically, this study explored the influence of habitat quality and
      individual-specific experience upon nest-site occupancy, breeding
      dispersal and reproductive success. It also estimated repeatability of the
      breeding parameters and examined the reproductive outcome of dispersal.
      Mixed models suggested that nestbox occupancy increased with population
      density but not habitat quality, and that the probability of dispersing
      varied by sex, with females more likely to disperse than males, and both
      more likely to disperse after breeding in noisier territories. Dispersal
      distance was not influenced by individual or habitat quality and did not
      influence reproductive success. Repeatability analyses suggested that
      habitat quality significantly influenced reproductive success.
      Furthermore, clutch size was strongly repeatable for females, but not
      males, whereas fledging success was repeatable between individual males
      but not females. If individual quality is consistent through their
      lifetime then these results suggest that female quality is important early
      in the breeding attempt, but that male quality exerts a stronger influence
      upon final fledging success.
      
      Both males and females increased their provisioning rate to larger broods,
      however, the other variables influencing each sex differed. Male
      provisioning rates decreased as both they, and their partner, aged, but
      increased when a mate was retained between breeding attempts. Females
      increased their provisioning rate in response to their partner’s effort
      and provisioned at a higher rate after retaining their nest-site. However,
      retaining mate or nest-site did not result in higher reproductive success
      for either sex. The repeatability analysis suggested that females
      responded to the requirements of their brood, and the effort of their
      partner, whereas male care was less flexible. Additionally, total and male
      provisioning rates were repeatable for each nestbox, suggesting an
      influence of habitat quality. Overall, different behaviours and decisions
      were found to be varyingly influenced by individual, and habitat, quality
      and the repeatability analyses aided in assessing the relative
      contribution of each of these.