New Zealand’s iconic yellow-eyed penguins – displayed on billboards greeting people arriving at the country’s main airports – could become extinct from the mainland in 25 years, scientists have warned.

Once-busy breeding grounds are now “overgrown and silent” with just a few pairs trying to carry on as birds are caught in fishing nets, are killed by unidentified toxins in the sea and suffer because of the general degradation of the marine environment by humans.

Global warming is also thought to be playing a part in the animal’s demise, according for about a third of the population decline.

The penguins’ decline comes despite its use as a means to attract tourists to the country.

New Zealand’s other famous bird, the kiwi, is also in trouble with the northern brown kiwi and the Okarito brown kiwi both classed as endangered by the International Union for Conservation of Nature.

In a new study, researchers developed a model to predict what will happen to the yellow-eyed penguins on the Otago Peninsula over the next few decades.

Published in the journal PeerJ, the results produced by one model found the birds would become locally extinct by 2060 as rising ocean temperatures impact their ability to breed successfully.

However, when mass ‘adult die-off’ events – such as the deaths of more than 60 in 2013 – were factored in, this brought the extinction date much further forward.

Dr Ursula Ellenberg, of La Trobe University, who has researched yellow-eyed penguins for the past 14 years, said: “It is sobering to see the previously busy penguin-breeding areas now overgrown and silent, with only the odd lonely pair hanging on.”

The lead author of the research paper, Dr Thomas Mattern, pointed out the bird’s status in New Zealand. In addition to being used to promote the country as a tourist destination, they also appear on the country’s $5 note.

“Yet despite being celebrated in this way, the species has been slowly slipping towards local extinction,” he said.

“The problem is that we lack data to examine the extent of human impacts, ranging from fisheries interactions, introduced predators to human disturbance, all of which contribute to the penguins' demise.

“However, considering that climate change explains only around a third of the variation in penguin numbers, clearly those other factors play a significant role.

“Unlike climate change, these factors could be managed on a regional scale.”

Animals in decline Show all 8 1 /8 Animals in decline Animals in decline Harbour seal (Phoca vitulina) Where: Orkney Islands. What: Between 2001-2006, numbers in Orkney declined by 40 per cent. Why: epidemics of the phocine distemper virus are thought to have caused major declines, but the killing of seals in the Moray Firth to protect salmon farms may have an impact. Alamy Animals in decline African lion (Panthera leo) Where: Ghana. What: In Ghana’s Mole National Park, lion numbers have declined by more than 90 per cent in 40 years. Why: local conflicts are thought to have contributed to the slaughter of lions and are a worrying example of the status of the animal in Western and Central Africa. Animals in decline Leatherback turtle (Dermochelys coriacea) Where: Indonesia, Malaysia, Mexico, Costa Rica. What: Numbers are down in both the Atlantic and Pacific. It declined by 95 per cent between 1989-2002 in Costa Rica. Why: mainly due to them being caught as bycatch, but they’ve also been affected by local developments. Alamy Animals in decline Wandering albatross (Diomedea exulans) Where: South Atlantic. What: A rapid decline. One population, from Bird Island, South Georgia, declined by 50 per cent between 1972-2010, according to the British Antarctic Survey. Why: being caught in various commercial longline fisheries. Alamy Animals in decline Saiga Antelope (Saiga tatarica) Where: Kazakhstan, Mongolia, Russia, Turkmenistan, Uzbekistan. What: fall in populations has been dramatic. In the early 1990s numbers were over a million, but are now estimated to be around 50,000. Why: the break up of the former USSR led to uncontrolled hunting. Increased rural poverty means the species is hunted for its meat Animals in decline Swordfish (Xiphias gladius) Where: found worldwide in tropical, subtropical and temperate seas. Why: at risk from overfishing and as a target in recreational fishing. A significant number of swordfish are also caught by illegal driftnet fisheries in the Mediterranean Animals in decline Argali Sheep (Ovis mammon) Where: Central and Southern Asian mountains,usually at 3,000-5,000 metres altitude. Why: domesticated herds of sheep competing for grazing grounds. Over-hunting and poaching. Animals in decline Humphead Wrasse (Cheilinus undulatus) Where: the Indo-Pacific, from the Red Sea to South Africa and to the Tuamoto Islands (Polynesia), north to the Ryukyu Islands (south-west Japan), and south to New Caledonia. Why: Illegal, Unregulated and Unreported (IUU) fishing and trading of the species

The researchers urged the Government to take steps to save the animal.

In the paper, they wrote: “Now we all know that yellow-eyed penguins are quietly slipping away we need to make a choice.