Wednesday, October 21, 2020

The influence of experience, pair bond duration, and partner change on breeding frequency and success in southern Buller's mollymawk ( Thalassarche bulleri bulleri )

TitleThe influence of experience, pair bond duration, and partner change on breeding frequency and success in southern Buller's mollymawk ( Thalassarche bulleri bulleri )
Publication TypeJournal Article
Year of Publication2002
AuthorsSagar, PM, Stahl, J-C, Molloy, J
JournalNotornis
Volume49
Issue3
Pagination145-152
Type of Articlepaper
Keywordsalbatrosses, breeding experience, pair bond, population, Procellariiformes, The Snares
Abstract

We investigated whether breeding frequency and breeding success of southern Buller's mollymawks (Thalassarche bulleri bulleri) were influenced by breeding experience and pair bond duration, using data from annual checks at 3 study colonies at The Snares from 1992 to 2001. Most pairs bred annually irrespective of the experience and length of the pair bond, although the proportions that did so varied with pair type. Thus, breeding frequency (% breeding in consecutive years) was lowest among pairs of 1st-time breeders (77%). Breeding frequency of those pairs after their 2nd attempt (89%) became similar to that of established pairs together for at least 1 previous breeding attempt (88%), or newly formed pairs in which one or both birds had previous breeding experience (91%). Overall breeding success was 71% and, in established pairs, breeding failure (loss of egg or chick) was associated with reduced breeding frequency (83% compared to 91% when successful). Lowest breeding success (58%) was associated with the attempts of 1st-time breeders. Performance of these pairs improved until the 3rd attempt (81%), when it became similar to that of established pairs (73%) and newly formed pairs in which one or both birds had previous breeding experience (77%). Divorce was rare (1.1-3.5% annually). First-time and former breeders mated more frequently with birds of similar status (85% and 58% respectively) than expected assuming random pairings. When changing partner, as a result of divorce or death, the average interval before breeding again was 2.1 years for males and 2.6 years for females, and so, on average, each change of partner resulted in the loss of 1 breeding attempt. Thus, the time taken to obtain a new partner has a lifetime reproductive cost.

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