Reproduction Of The Black Redstart P.O. Rufiventris In The Southeastern Qingzang (Qinghai-Tibetan) Plateau

The reproduction of the black redstart Phoenicurus ochruros rufiventris was investigated in the Southeastern Qingzang(Tibetan)Plateau,at an altitude of 3470m.This paper' s aim is to quantify the reproductive parameters and to identify the main factors which impact the birds' breeding habitat selection and affect their reproductive success rate;and examine whether the young would grow faster and have a smaller clutch of larger eggs and higher fledgling rate when living at higher altitude.The nests of Black Redstart were built in holes,everage hole width was 9.62±3.85cm,everage hole height was 8.28±3.15cm,hole to uppside length was 52.39±38.74cm,hole to lowside length was 107.02±81.03,nest to hole distance was 31.74±24.87cm.The nest was bowl shape and built with dry grass,thin branches and so on inside,outside was hair and feather and so on.The nest inside diameter was 6.94±0.67cm,nest outside diameter was 12.5±2.37,nest depth was 3.46±0.48 cm,nest heigth was 5.9±1.39 cm,nest weight was 53.4±13.05g.The egg was weak green.The average clutch size was 4.8 and egg size averaged 23.33 mm×14.95 mm The egg weight was 12.05g.Compared with closely related species at low elevation,the Black Redstart had smaller clutch of larger eggs.Only the females incubated their eggs and the incubation period lasted 13-14 days.The incubation rate was 64.5%.Both the female and the male fed their nestlings.The nest success rate was 81.3%.Nestling period lasted 16-19 days and the fledgling rate was 83.33%.Here we found female laid two broods.The redstarts at higher altitude had smaller clutch of larger eggs and provided greater parental care to their offspring,so that the young had greater fledgling rate.It was a compensation for reduced fecundity.In low temperature condition,greater parental care hadn't made the offspring grow faster than those of closely related species in low altitude. We concluded that longer nestling period was not only the need for increasing the young' s quality,but also a result of natural selection due to action of hypoxia and low temperature...