Isle of Rum: The remote Scottish island home to a world renowned deer study

Research from the University of Edinburgh on the Isle of Rum's red deer population has led to world-first discoveries, as ITV News Scotland Reporter Louise Scott explains

On Scotland's west coast lies the Isle of Rum. Shaped like a diamond, the Isle is referred to as the jewel of the Inner Hebrides.

Only 30 people inhabit this remote island, which is home to deserted beaches, dramatic landscape and a plethora of wildlife.

It's also host to the world's longest study of deer, which is this month celebrating it's landmark 50th anniversary.

An estimated 1,000 red deer live on the island, of which 250 have been studied by the University of Edinburgh over the past five decades.

Scientists have uncovered ecological and evolutionary forces driving changes in animal populations, informing management practices around the world.

In recent years, they've discovered some of the first evidence that wild animals are evolving to give birth earlier in the year as the climate warms.

Some 1,000 red deer live on the Isle of Rum. Credit: ITV News

Researchers found that deer have been giving birth earlier since the 1980s, at a rate of about three days per decade.

Josephine Pemberton is part of the Isle of Rum Deer Project and has studied the herd for 39 years. 

She told ITV News: "Giving birth is the result of when they conceive, because pregnancy is fairly fixed.

"So, it's all about the summer weather conditions the year before. What we're getting to now, is that some of this effect is individual females responding within their lifetimes to better growing conditions.

"So, they get pregnant earlier and have calves earlier. I think it will all be in the growth of the vegetation; warmer summers and suitable amounts of rain mean better plant growth, and that causes the animals to get into condition earlier in the autumn."

Josephine Pemberton (left) is part of the Isle of Rum Deer Project. Credit: ITV News

Female red deer, called hinds, give birth to a single calf each year.

June is the key calving month and so it's all hands-on deck to monitor and track the newborn calves.

The team, which includes PhD students, are stationed at lookout points around the study area. Telescopes and binoculars are used to track the hinds and spot any signs of newborn calves.

Each calf then has its ear tagged, weight taken, and blood sampled for DNA analysis at the University of Edinburgh. 

At this stage, the scientists will be able to work out which stag is the father through genetic analysis and, furthermore, which characteristics are inherited.

Sarah Dobson (left) is one of a number of PhD students who help track red deer on the Isle of Rum. Credit: ITV News

The team closely monitor how events in early life go on to affect the deer.

Josephine said: "We've found that after warm springs the calves are born heavier. If a year class gets a nice winter, you have a cohort which goes through the whole of life at an advantage compared to another cohort.

"This is all about weather differences in the year of birth. I think it was first documented on this project and is now a well known phenomenon."

They have also been able to document the aging process of the deer, which historically wasn't expected in a wild animal.

Female red deer give birth to a single calf each year. Credit: ITV News

It was previously understood that they would become too weak to survive, but the study has found wild animals' senescence much like humans.

Josephine says the longevity of the study has allowed for these discoveries to be possible.

"You can't understand a long-term trend without your baseline data, so it's amazing that this project started so early and that we can now check these things," she added.

"There isn't anywhere else in Scotland or the UK where you can check what is going on in a large mammal like this."

Calving season will continue until the end of June, with each newborn adding to the potential discoveries that will continue to shape our understanding of wild animal populations around the world.

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