Comment by ileonichwiesz

That’s the more likely hypothesis, but I also wonder if different land management practices could be influencing a map like this. Agriculture in Poland is much more fragmented than in Germany - smaller fields of different crops, often separated by meadows and forests, creating lots of niches for biodiversity. In Western Europe you’re more likely to see giant, mechanised monoculture fields as far as the eye can see, leaving less space for agrarian-landscape wildlife.