mating

• by chaosd

  So do Gentoo become bonded pairs or do they play the field?

  Posted June 22, 2016 4:52 PM

• by AvastMH moderator

  Well it's generally taken that they remain bonded, but science shows that this is not always the case.
  I found the following information from a useful site called 'Photovolcanica':

  The pre-breeding period is short and in poor years the penguins may delay their arrival and / or only sporadically attend the nest after arriving due to continued foraging during the day. This is in stark contrast to e.g. Macaroni Penguins which remain at the nest site during pre-breeding. This behaviour may account for the large fluctuations in mate fidelity observed during a several year study at Bird Island, S. Georgia since it may reduce the probability of the partners reuniting and reestablishing a pair bond via the usual courtship rituals (Williams and Rodwell 1992. Condor 94, p.636-645). Whilst in normal years mate fidelity reaches nearly 90%, in 1987, when food was scarce, none of the 13 study pairs that mated in the previous season did so again. In 38% of these pairs both birds were present, yet divorce took place, whereas in the remaining cases at least one partner was absent, probably dead. In fact, only 20% of the previous years breeders appeared to return to breed in 1987. Usually, this figure can reach 80%. Nest fidelity was high in all years at Bird Island, with between 89 and 100% of returning birds using the same nest as in the previous season. Where divorce occurred, the male tended to stay at the nest site.
  Previous data from the S. Shetlands also had found 90% mate fidelity, but at Crozet mate fidelity only appears to be about 50%. This is probably the result of the unusual extended breeding season at this site which involves reduced synchrony at the onset of the breeding season.

  I'll just add a brief word about synchrony. We've seen a lot of pictures of a Chinstrap site that we nicknamed Ice Age, and where a lot of them can be seen making ecstatic calls at the same time. this event synchronises the breeding season within that colony which aids its success:

  

  https://talk.penguinwatch.org/#/subjects/APZ0009hdv

  Posted June 22, 2016 5:20 PM

• by chaosd

  Oh. Thanks! It makes sense that it would wane in some years of food scarcity. Thanks!

  Posted June 22, 2016 10:29 PM

• by AvastMH moderator

  You're welcome 😃

  Posted June 22, 2016 10:37 PM