Complex sentence: Around 1950, conservation laws were introduced in southern Europe to protect the species and numbers began to increase, and by the beginning of the 21st century the bird was breeding again in France, the Netherlands and Britain.
Split into simpler sentences: Around 1950, conservation laws were introduced in southern Europe to protect the species and their numbers began to increase. By the beginning of the 21st century the bird was breeding again in France, the Netherlands and Britain.