When an unwanted visitor enters the snow petrel's nest, it could cop a spray of thick, oily spit.

Key points: Snow petrels are one of the few Antarctic seabirds to stay within the ice zone during winter

Snow petrels are one of the few Antarctic seabirds to stay within the ice zone during winter They use their oily spit as a defence mechanism

They use their oily spit as a defence mechanism Fossilised bird spit is helping scientists learn more about the species and the Antarctic landscape

But scientists hope that fossilised remains of the Antarctic sea bird's saliva will shed light on its history — and its future.

"[The spit is] a rich, thick oil and they feed their chicks with that but they also use it as a defence mechanism," said Louise Emmerson, leader of the Seabird Research Group at the Australian Antarctic Division (AAD).

"If a predator came to the nest they would spit at that predator and that would cover their predator.

"If it was a bird, it would cover their feathers in thick, goopy, oily, rich stuff and that would make the feathers really compromised in terms of their waterproof ability."

Snow petrels aren't a commonly researched bird.

"We don't know all that much about [snow petrels] compared with other species like penguins," AAD ecologist Colin Southwell said.

Dr Marcus Salton chisels fossilised snow petrel spit known as "mumijo". ( AAD: Marcus Salton )

But scientists are certain about one thing — they're tough.

"They don't look tough, they are quite an elegant bird," Dr Southwell said.

"They are quite delicate to look at [so] to live in the environments they live in — flying around in the ocean, breeding in places that have temperatures down to minus 40 [degrees Celsius] or so — is astonishing."

Fossilised spit used to predict the future

While most Antarctic seabirds will head north during winter, the snow petrel is one of the few species which stays in Antarctica while the ocean is covered in ice.

They can go foraging for up to a week and travel distances of 900 kilometres to find food for their young.

"Snow petrels are quite amazing, we've got some data showing they can actually fly around Antarctica during winter they have got this amazing navigation ability," Dr Emmerson said.

Project leader Louise Emmerson (R), with colleagues Marcus Salton (L) and Colin Southwell. ( ABC News: Fiona Blackwood )

Layers of snow petrel spit have accumulated at breeding sites across Antarctica over thousands of years.

"There have been some previous samples from other parts of Antarctica that were dated back to 37,000 years," Dr Emmerson said.

Last year, a team of scientists went to a nesting site about an hour's drive from Mawson station to collect samples of the fossilised spit, known as "mumijo".

"Imagine getting a cake and putting it in a freezer so it is rock hard and then trying to cut it with a knife … it is really challenging. We ended up using a hammer and a chisel," field biologist Marcus Salton said.

The samples will be sent to Germany where they will be radio carbon dated.

It is expected they will date back a few thousand years.

The research aims to predict how the snow petrel will respond to environmental changes. ( AAD: Peter Layt )

The snow petrel nests in crevices between rocks around the continent of Antarctica.

"They are almost invisible when they come from the ocean to the land to breed. They can be in their nest but if you were to walk through landscape looking for snow petrels you might not see any," Dr Southwell said.

"We want to know what areas snow petrels have been living in for a very long time and whether they have been able to weather the storms of the environmental change that those areas have experienced," Dr Emmerson said.

Scientists will use geological records to work out when the landscape became ice free and when the snow petrels moved in.

"We can work out what conditions the snow petrels experienced when they first colonised those areas and what the lag is between that land becoming available for breeding and the snow petrels moving into that area," Dr Emmerson said.

That information will help predict how the snow petrel will respond to environmental changes in the future.