XING'AN LEAGUE, April 9 (Xinhua) -- Tens of thousands of migratory birds are making seasonal stops in the grasslands and wetlands of Xing'an League, Inner Mongolia Autonomous Region, during their annual migration.The flocks include protected species such as Siberian cranes and red-crowned cranes, which travel long distance between their breeding and wintering grounds. Local authorities have stepped up conservation efforts to safeguard these important stopover habitats.