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Parental attendance of Common Guillemots during chick-rearing
Common Guillemot
  1. Parental attendance is the amount of time that one or both parents spent at the nest site.
  2. For the Common Guillemot, at least one parent must be present to protect the egg or chick from predation.
  3. Time at the colony can be spent at the breeding ledge or on a loafing ledge.
  4. Time away from the colony can be spent in flight, on surface activities, or in diving.
  5. Adults can return with or without fish.
  6. Chicks require 30-60g of fresh fish per day (Gaston and Jones 1998)
  7. Adult Guillemots require 440g of fresh fish per day during foraging. (Gabrielsen 1994, quoted in Gaston and Jones 1998)
  8. Captive adults took up to 200g of fish at a meal, including individual fish up to 113g. Normally consumed 55-65g per meal if fed regularly. Birds took 3 hours to consume c.60g of fish (Golovkin 1963, quoted in Bradstreet & Brown 1985)
  9. Time spent diving (and therefore estimated energy expenditure) increases in years of low food abundance (Uttley et al. 1994)
  10. It has been shown that parental attendance during chick rearing is a good indicator of prey abundance. (Zador & Piatt 1999, etc).
  11. Parental atttendance / prey abundance relationship is consistent throughout the range of the Common Guillemot.
    1. Shetland (Uttley et al. 1994, Monaghan et al. 1994)
    2. Cook Inlet, Alaska (Zador & Piatt 1999, etc, Harding et al. 2007)
    3. Newfoundland (Burger & Piatt 1990, Davoren & Montevecchi 2003, Wilhelm et al. 2008)
    4. North Sea (Wanless et al. 2005, Ashbrook et al. 2008)
  12. Extremely low levels of prey fish may cause both parents to leave the chick unattended, leading to aggression from neighbouring breeding Guillemots. (Ashbrook et al. 2008)
  13. Non-breeding or failed breeders still show alloparenting behaviour in conditions of reduced prey abundance. (Ashbrook et al. 2008)
Measures of parental attendance

  1. Bird-minutes per hour (Zador & Piatt 1999). Also expressed as a percentage.
  1. What are the weights of provisioning adults?
  2. How does feeding affect an adult's flying ability?
  3. What is the time budget of an adult on a foraging trip?
  4. What factors influence an adult to leave the ledge?
  5. What factors influence an adult to return with a fish?

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