Wild Soay sheep live in a cold environment on a small Scottish island. The sheep used to be large because they gained extra weight during the summers in order to survive the harsh winters. A recent change in the island’s climate has caused grass to be available for a longer period each year, so survival conditions for the sheep have become less challenging.
Technically, I don't see a question, just a statement abut sheep.
That's an interesting fact about the Soay sheep and how they have adapted to their environment! If you have any specific questions about this, feel free to ask.
Answer: Size
Researchers who study these sheep have most likely observed a decrease in the wild Soay's SIZE.