Even if so, building more wind turbines will kill more birds while building more nuclear plants will not kill more birds.
It would also be interesting to see the data relative to something. Maybe it's 200'000 birds on a total of 100 wind turbines (or 1'000, 10k, 100k, ...).
Thermal powerplants are killing machines in their own right. They might not kill birds but they can kill fish by the millions and if you run them near a river then the temperature increase can kill the entire river when seasonal flow rates are low which leads to premature shutdown of the nuclear powerplant just to avoid killing aquatic life.