Cookies Policy
Cookie Policy

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies.

I accept this policy

Find out more here

Non-breeding Nazca Boobies (Sula Granti) Show Social and Sexual Interest in Chicks: Behavioural and Ecological Aspects

MyBook is a cheap paperback edition of the original book and will be sold at uniform, low price.

Buy this article

$30.00+ Tax (if applicable)
Add to Favorites

image of Behaviour

Adult Nazca boobies (Sula granti) show an unusual interest in both conspecific and congeneric nestlings, visiting them at their nest sites and performing mixtures of affiliative, aggressive, and sexual behaviours. Using a 20 year database from a large Nazca booby colony on Isla Española, Galápagos Islands, Ecuador, we describe the behaviour and the individuals performing the behaviour. Non-parental Adult Visitors ('NAVs') are typically 'unemployed' (non-breeding birds or recently failed breeders), and make visits of 1-60 min to unguarded chicks. Males and females are equally likely to exhibit the behaviour, if they are unemployed; since most unemployed birds are male, due to a sex ratio bias, most NAVs are male. Very young chicks and chicks nearing fledging are not visited, because young chicks are always attended by protective parents, and old chicks can defend themselves. When acting affiliatively, NAVs may simply stand by the chick, or may preen it and present gifts of pebbles and feathers. Aggression by the NAV often leaves scratches on the chick's body, but seldom causes the chick's death directly. However, landbirds take blood-meals from the scratches during food shortages, deepening the wound and eventually killing the chick. The least common NAV behaviour is sexual, in which adults perform male copulatory behaviour with the chick. Sexual behaviour occurs in 14.3% of visits by males, and 6.8% of visits by females. NAV behaviour is the direct or indirect cause of mortality of up to 24.6% of chicks, representing up to 41.6% of all deaths, in a given year. Approximately 80% of non-breeding birds in a given year show NAV behaviour, and since most adults are non-breeders at some point in life, most adults show NAV behaviour at some point. We propose a number of hypotheses to explain the causation of this puzzling and ecologically important behaviour.


Can't access your account?
  • Tools

  • Add to Favorites
  • Printable version
  • Email this page
  • Create email alert
  • Get permissions
  • Recommend to your library

    You must fill out fields marked with: *

    Librarian details
    Your details
    Why are you recommending this title?
    Select reason:
    Behaviour — Recommend this title to your library

    Thank you

    Your recommendation has been sent to your librarian.

  • Export citations
  • Key

  • Full access
  • Open Access
  • Partial/No accessInformation