Three decades of data show the females of this species are being born smaller, and those that do survive to motherhood are breeding later in life.

 

Subtle changes in their genetics are also being recorded.

 

Researchers tell the journal Nature that a shift in a dominant¹ climate pattern has affected² the supply of the seals' primary food source - krill.

 

"There has been a significant reduction in the size and the mass of the pups at birth," explained Dr Jaume Forcada from the British Antarctic Survey (BAS).

 

"Over 27 years, we see pups being born with 8% less body mass. We also see the females breeding later in age - at least by one or two years. 

 

"And when they start breeding, they are bigger than they used to be 30 years ago. This kind of thing has been seen before in all sorts of mammals, and is classically an indication of food stress."

 

The study was centred on South Georgia, a British Overseas Territory (BOT) in the South Atlantic that falls within the influence of Antarctic waters.

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