One of the top predators in Antarctic waters, male southern elephant seals have a fair selection of the menu.
But it turns out the giant mammals, which can weigh up to four tonnes, are picky eaters.
It's a trait that could prove a double-edged sword as the species faces the threat of global warming and ecological change.
Research led by the University of NSW analysed whisker samples from 31 males from the Western Antarctic Peninsula to uncover clues about their diet.
Each whisker contained up to a year's worth of data about their preferences.
They determined nearly all males were "specialists" who consistently consumed the same food.
Most of the cohort were considered extreme specialists who ate less than 20 per cent of their environment's range of food.
"They could have the pick of the buffet, yet each male southern elephant seal eats a lot of the same food ... just a fraction of what's on offer," lead author Andrea Cormack said.
"They are extremely picky eaters, each with their own unique favourite foods they go after, whether it be fish, squid species, crustaceans or octopus."
The exact reason for the males' eating habits is unknown but could relate to their bite size, feeding technique and prey availability.
Ms Cormack said being a specialist can be beneficial - the seals could be diving deep to avoid competition from other predators.
"On the flip side though it can also mean they're limited in their behavioural plasticity - their ability to naturally adapt," she said.
"What we could possibly see in the future is (issues) if these guys aren't able to pursue other food.
"It can go one of two ways ... research needs to understand in more depth what direction (specialisation) may be taking them."
Marine ecologist and senior study author Tracey Rogers said ice cliffs on the Western Antarctic Peninsula were almost completely gone.
The time when new ice forms was also getting shorter, challenging the whole ecosystem, Professor Rogers said.
Ms Cormack said the elephant seal population had bounced back after being hunted to near-extinction in the 1900s.
"As a whole, they are stable. But in saying that, a couple of major groups in the Southern Ocean are declining and that is concerning," she said.
"Climate change in the Southern Ocean is variable, not all areas are responding the same."
The study was published in science journal Marine Ecology Progress Series.
