Studies On Breeding Ecology Of Great Bustard

We studied the activity rules, especially the courtship display behavior and breeding biology of Orient subspecies Great Bustard (Otis tarda) during its breeding season in Tu-mu-ji nature protective area of Inner Mongolia between 2000 and 2001, the main results are as following:1. By investigating, we found that the density of Great Bustard is 0.10 individual/km2 during its breeding season in the region,and the density decreased significantly compared with the density in 1992.The sex ratio of male and female is 0.88:1. The population quantity of Great Bustard fluctuates signifucantly during the breeding season, there are more Great Bustard during the period April and May than June and July.2.We adopted the method, direct observation to study wild Great Bustard rationly for the first in China. The behavior time budget of Great Bustard is different between male and female during the breeding season, at the same, it changes following the breeding stages. The feeding and courtship display behavior show obvious day rhythm, and exist diferent between male and female.The Great Bustard hasn't strong behavior of occupying territory and defending territory, the male has territory when displaying in some degree,to drive the same sex individual when it enters its territory. The territory area of Great Bustard is 943 + 419m2(n=6). Male Great Bustard has the behavior to gather to display in the displaying fields. There exists grade between males. The display fields areas are about 3.89km2 and 5.41km2.4. I studied the courtship behavior of Great Bustard roundly for therfirst time, and I divided the courtship into two types: attracting courtship display and acting courtship display. The courtship display mainly is acting courtship display during the mating period; the courtship display mainly is attracting courtship display during the period that after mating to the end of display period. Female has the behavior to select mate voluntary. The wedding system is typical male dominance polygyny.5.The Great Bustard has abundant time to breed, its breeding season last from first April to the middle ten days of July, once a year, but it maybe build nest to lay again when the first nest was destroied. Great Bustard bends over in nest with fixed orientation during the hatching period. The nest of Great Bustard is simpleness. Clutch size varys between 2 and 5, average clutch size is 2.52?.98(n=53). The female Great Bustard has the behavior to turn over eggs and move eggs during the hatching pereiod. The home range of female is biggest (14970 +569m2 ?during the building nest period and that is the smallest(5609?18m2 during upper-hatching period.6.The nest-site selection of Great Bustard is strict, it mainly selects the grassland with small hill which with gradient slow and nest above the middle parts of hill. Slope orientation that it select is mostly towards the south and the sun. The factors that in fluences the nest-site selection of Great Bustard mainly are the hight and density of vegetation. The abandoning eggs rate is 76.19%.7. The nestling of Great Bustard is precocity bird.the body weight is 86.31+3.56g when nestlings were hatched.There exists obvious difference between the growth of male and female,the growth speed of male nestlings exceed female nestlings Great Bustard.