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RADOLFZELL, Germany, Dec.
Not just birds, but also a few species of bats face a long journey every year.
The numbers of overwintering waterbirds at Lake Constance, a large lake on the borders of Germany, Austria and Switzerland, have increased fourfold since the early 1960s, with a daily average of 162 500 waterbirds from September to April as shown by a study published in the august issue of Freshwater Biology. This massive increase coincides with the major expansion of zebra mussels in the lake, originating in the Caspian-Aral basin, and a major pest in Europe and North America.