Re-use of courtship nests for quick remating in the polygynous Fan-tailed Warbler Cisticola juncidis

In a population of Fan-tailed Warblers Cisticola juncidis near Osaka, Japan, the males were polygynous, building a succession of elaborate courtship nests within their territories, and advertising them to females. Nest desertion by females frequently occurred early in the breeding cycle. Deserted nests were generally left untouched, but 17 out of 88 territorial males cleaned and re-used 20 of 79 nests deserted by females for their next courtship. The frequency of nest re-use increased with season. Of the re-used nests six (300%) were re-occupied by secondary females. Newly built nests were preferred to the 'second-hand' nests, probably because new nests were likely to last longer. Breeding success did not differ between the two categories of nests. In males, nest re-use seems to save time and energy expenditure for additional mating.