| As an endangered migratory bird species, breeding population and habitats protection is of vital importance to maintain a thriving population for oriental white stork. The Yellow River Delta is one of the most important stopover sites of this species in China. Since their first appearance in 2003, the size of the oriental white stork population has increased dramatically in past seven years in this area, suggesting the necessity to learn the dynamic species population, breeding characteristics, as well as the habitats selection of this species, to provide site observed data and theoretical support for protection of endangered species.In order to obtain the basic information of the population and protect the oriental white stork effectively, population dynamics, habitat selection and utilization of the birds in Yellow River Delta were studied using route survey and sampling methods from July 2008 to July 2009. During the breeding season of 2009, quadrat sampling, instantaneous scan sampling and focal animal sampling methods were used to investigate the breeding habits and diurnal time-activity budgets of different behaviors of this species. Moreover, their strategy of feeding habitats was evaluated by detrended correspondence analysis (DCA).Dawenliu, a wetland restoration site, is the major distribution area of the oriental white stork. They were also found in the areas of the north bank of the Yellow River, as well as in coastal areas. The oriental white stork habitats utilization changes with seasons. During the freezing season (Dec 2008 to Feb 2009), no individuals were found in Dawenliu. In autumn, the habitat utilization ratio of this species were as follows:in early restored wetland at 41.04±40.75%, later restored wetland at 20.69±28.86%, shrimp ponds at 16.74±31.04%, reed ponds at 6.85±14.91%, nest area at 0.77±3.16%, paddy field at 0.11±0.41%. While in summer, habitat utilization ratio were as follows:in early restored wetland at 7.19±15.51%, later restored wetland at 11.32±0.55%, shrimp ponds at 8.16±16.43%, reed ponds at 1.36±4.68%, nest area at 71.07±34.15%. In spring, habitat utilization ratio were as follows:in harvested reed wetland at 36.73±29.52%, early restored wetland at 5.57±5.45%, later restored wetland at 5.57±5.45%, reed pond at 10.03±9.71%, ditch at 4.74±5.87%, nest area wetland at 33.79±14.87%, reed stubble wetland at 8.83±9.67%. Changing water level with seasons was the major factor influencing on habitat selection of the storks.Oriental white stork chose the nest sites in early February, and began to build nest in mid-late February. Nests were built on transmission poles, standing poles or pylons. In Dawenliu, nests were at the height of 13.25±2.07m (n=18), and the distance between the neighboring nests were 647.22±1086.49 m (n=18). In the Yellow River Inlet, nest were at the height of 25.50±7.97m (n=3), and the distance between the neighboring nests were 42640.00±62838.80m (n=3).The principal factors determining nest selection of the stork including water area, the disturbance from human distance, as well as the height and distance between the neighboring of nest and vegetation information.The earliest incubation began on February 25th. However, several disturbed breeding pairs postponed their incubation to mid-May. Incubation period lasted for 33.23±1.36 days, and parents caring was about 63.33±6.83 days (n=12). Parent birds fed their nestlings at a rate of 6.23±2.23 times per day (n=68). Nestlings left their nests from May 28th and late up to August 19th. Only 17 pairs of the 21 breeding pairs bred successfully with 47 eggs hatched and 37 nestlings survived to fledging. Strong wind was the major adverse factor for reproduction. In addition, human disturbance and lack of suitable nest sites also took effects on breeding success.Diurnal time-activity budgets for on-nest, mating, feeding, egg turning-over, resting, alerting, flying, fixing nest, fletching material, preening, others and out of eyeshot show significant difference(P<0.01), foraging (P=0.72) and bill clattering(P =0.07) show no significant difference during the breeding periods.According to DCA, the three highest score variables in the first axis were the distance to nest, vegetation height, and vegetation coverage. The three highest score variables in the second axis included vegetation density, number of other water birds, and the open water area. Oriental white stork foraged mainly in reed and swamp of restoration areas (70.29%) in early breeding period. While in late breeding period they prefer reed and swamp in non-restoration areas (32.74%) and surface (29.95%). In these two periods, vegetation density and distance to nest and the distance to the road showed significant difference (P<0.01), and vegetation height, the distance to the settlements and the cleanliness were also significantly different (P<0.05), showing that the feeding site selections of oriental white stork in breeding period changed with seasons and breeding process. We should pay more attention to the effects of water level on the habitat selection of the oriental white stork in the future protection work. It is important to maintain the water at reasonable level to ensure their needs of habitat in different periods. In order to increase the breeding success, it is necessary to provide more standing poles and fasten the nest bases on the standing poles. Practicable measures should be taken to reduce the disturbance of the tourists to the oriental white stork breeding.
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