The study assessed the lives of wild red deer on the Isle of Rum
A study of wild red deer on the Isle of Rum has found their ageing process can be dramatic and sudden.
Scientists at Edinburgh University studied a thousand of the animals, immortalised in Sir Edwin Landseer's portrait Monarch of the Glen.
They discovered that while males showed the first signs of ageing later than females, when it did catch up their decline could be much faster.
The research looked at the ability of the animals to reproduce as they aged.
Data taken from the past 40 years showed that after about the age of 10, stags quickly became less likely to father calves.
However, hinds, who showed signs of ageing from about nine years old, could go on calving into their late teens.
Researchers also found that the signs of ageing in wild deer could be deceptively complex.
Older stags appeared able to maintain their antlers well into old age, but despite this they had little success during the autumn rut and fathered very few calves.
Similarly, females which were past their prime were likely to continue breeding, but their offspring tended to be smaller and less likely to survive compared with calves born to younger females.
Dr Dan Nussey, from the University of Edinburgh's school of biological sciences, who led the study, said: "Recent research suggests that wild animals show signs of deterioration in old age, just like animals in captivity and humans, but this is the first study to look in detail at the impact of ageing on breeding in wild mammals.
"We were surprised at how complex the picture was: not only are there big differences between males and females, but the signs of ageing emerge at different times.
"More work is required to understand what is driving these differences. It all shows just how complex the ageing process is."
Kristin Scott, West Highland area manager for Scottish Natural Heritage, welcomed the study.
She said: "The researchers have used this well known population on Rum where the stags and hinds live out their lives in the relatively unspoilt and undisturbed landscape of this spectacular island national nature reserve."
The study by scientists from Edinburgh and Cambridge, was funded by the Natural Environment Research Council (NERC), supported by Scottish Natural Heritage (SNH) and is published in the American Naturalist.