Determinants of reproductive success in force-re-paired cockatiels (Nymphicus hollandicus)

Fifty-eight previously paired cockatiels were force-re-paired based on bree ding history to determine the relationship between reproductive experience and nesting success. Males (M) and females (F) were assigned a breeding his tory that was 'experienced' (E) or 'inexperienced' (I), depending on whethe r they were part of a pair that had hatched at least one egg during the pas t two breeding trials. Re-pairing resulted in four groups designated EMEF, EMIF, IMEF, and IMIF. Nesting success was defined as incidence of, or laten cy to, nest inspection, nest-bowl formation, and egg laying, as well as hat chability of eggs. Additionally, age, pre-laying nestbox occupancy, and rel ative cage height were evaluated for relationship to nesting success. Eight weeks after re-pairing, birds were exposed to environmental stimuli for br eeding, and nestboxes were checked daily for evidence of nest inspection, b owl formation, oviposition, and hatching. Videocameras recorded nestbox occ upancy for 4 h every other day. Overall, groups differed significantly in t he number of pairs that inspected nests and formed bowls; nest inspection w as lowest for LMIF, and bowl formation was highest for EMEF. When groups we re combined based on male breeding history, significantly more EM than IM i nspected nests and formed bowls. Comparing groups based on female breeding history, significantly more EF than IF inspected nests and formed bowls. On ly EF laid eggs, and mates of EF's that laid spent significantly more pre-l ay time in the nestbox than did mates of EF's that didn't lay. Pairs in ele vated cages inspected nests and initiated clutches significantly more than did lower tier pairs. Results of this study should be useful to aviculturis ts trying to select bird combinations and aviary design to maximize product ivity. (C) 1999 Elsevier Science B.V. AU rights reserved.