Study On Moulting And Nesting Ecology Of Yellow-bellied Prinia, Prinia Flaviventris

The yellow-bellied Prinia (Prinia flaviventris) belongs to Cisticolidae of Passeriformes, it is widespread in south of China and its tails have converse change compared with other species. That may means a new survival strategy, and there have ectopia changes between courtship behaviors, territorial behaviors, sexual selection and the length of the body changes in time. The mode have not been studied yet. To explore the new survive strategy, we studied moulting and nesting of yellow-bellied Prinia to find out the clue to the mode, which might reveal a new survive strategy.The length of the body and tail in breeding season was highly significant (P < 0.01) shorter than non-breeding season, the length of wing was significant shorter (P < 0.05), other body measurements had not significant difference between breeding and non-breeding season ( P > 0.05). Body length changes are mainly caused by the tails changes. The specimen of Yellow-bellied Prinia got at 17th September showed that 5th primaries and 6th secondaries had been replaced, while the specimens collected after 20th November had finished the moult process. The pattern of primaries replacement was descendant and Secondaries was ascendant, and tail feathers replaced as a centrifugal moulting pattern. Body-mass varied during moulting periods and reached its maximum in October when the body mass was significantly heavier than November ( P < 0.01). However, no any significant difference in body mass was found between the remainder months (P > 0.05).The yellow-bellied Prinia started spring moulting from March to May, lasted about 60 days. Compared with autumn moulting, spring moulting of the yellow-bellied Prinia defined as incomplete moulting, for it only moulted tails but not remiges. The tail feathers replaced as a centrifugal moulting pattern, and tail length and width exist highly significant plus correlation(P < 0.01), but not changed proportionately.The yellow-bellied Prinia started courtship call in Mar and started nesting in the middle of March, reached its peak in April, and was completed by late July. Totally 44 nests were found in 13 species of plants, and 27 nests were built in Pennisetum purpureum, 4 in Erigeron canadensis and 1 or 2 in others. All nests were irregularly sphere-shaped, included artifactitious materials besides vegetal, creatural and inside space of nest was according to the nest size. Four factors were found to affect birds selecting their nest-sites: distance from the nearest water sources(29.89%), distance from the nearest road(16.45%), distance from the nearest bush(12.92%), and height above water surface(11.69%).So we supposed that the yellow-bellied Prinia's tails had converse changes based upon the following strategies: Before breeding season, longer tails of the yellow-bellied Prinia have more advantages in fighting for females and mating and so on, although it needed higher energy expenditure for flying, the yellow-bellied Prinia could get best trade-off. During the period of breeding season, the main behaviors of the yellow-bellied prinia were nesting, feeding and other breeding activities, so shorter tails could increase flexibility. At the other hand, shorter tails could reduce sizes of nest entrance and nest deepth and so could reduce nest building investment by parents.