Complex sentence: By 2005, the Rare Breeds Survival Trust had moved the breed to "at risk" status, meaning there were less than 1,500 breeding females living, but by 2010 they had been moved back to vulnerable.
Split into simpler sentences: By 2005, the Rare Breeds Survival Trust had moved the breed to "at risk" status, meaning there were fewer than 1,500 breeding females living. However, by 2010 they had been moved back to vulnerable.