DNA samples show that outer Hebrides deer are not likely tro have come from the mainland, and it’s suggested that Neolithic peoples imported them. From Jonathan Webb at BBC News:
Red deer, the largest of modern British land animals, were banished from most of western Europe and restricted to southern Spain during the last Ice Age.
When the ice retreated about 10,000 years ago, these and other beasts – including humans – gradually repopulated northern regions. But red deer didn’t make it to these outer Scottish isles until about 5,000 years ago.
Humans, which were increasingly adopting domestication during this period, are thought to be responsible for the deer’s arrival – but the new study casts doubt on the obvious idea that they shipped them from mainland Scotland.More.
We don’t know much about northwest European seafaring during the period and we tend to underestimate our ancestors. Wouldn’t it be a gas if Neanderthals turn out to have been using remote islands as a food resource in times of scarcity?