A one-tonne southern elephant seal named Neil, whose beachside antics have attracted millions of views on social media, appears to have returned to sea.

The five-year-old has spent several weeks at his usual twice-yearly haul-out spot in southern Tasmania.

Videos of Neil crushing signs and poles and lounging on suburban streets near fences have gone viral online and attracted streams of visitors to the otherwise sleepy coastal town.

But on Thursday, Tasmania’s Department of Natural Resources and Environment (NRE) said it appeared Neil had left the area.

“Neil the Seal returned safely to sea last night. This is his natural behaviour and was expected,” the department said in a statement.

He may still return or haul-out at a nearby location in the short term, they said, or be off to southern feeding grounds.

NRE said its marine conservation program was monitoring the situation.

However, authorities were unable to directly track Neil. An NRE spokesperson told the Guardian that while a satellite tracking device was attached to Neil in 2023, it fell off during his annual moult “as expected and was recovered in 2024”.

“Neil has not been tracked since 2024, as attaching a tracking device is usually done during a specific need like if veterinary or relocation intervention is undertaken,” they said.

Neil nuzzles up to bollards he has damaged. Photograph: Sam Volker Photography/AP

When the then teenaged seal was able to be tracked, data showed that he spent six months at sea, foraging over 1,600km from the south-west of Tasmania, covering a distance of more than 5,000km during the round trip.

“This is normal behaviour for a young male southern elephant seal,” they said.

Neil’s departure came as the crowds of visitors flocking to see the local celebrity reached potentially dangerous levels.

Wildlife authorities issued a firm warning, telling people to keep their distance from Neil and saying euthanasia was a last resort if public safety could not be guaranteed.

Neil was born in southern Tasmania without a colony and is pre-programmed to return to the area twice a year to rest and moult. Tasmania’s southern elephant seal colonies were wiped out by sealers in the 1800s, and most breed on Macquarie and Heard Islands.

Kris Carlyon, the head of wildlife health and marine life at NRE, said Neil was “potentially one of the first southern elephant seal pups to be born back in Tasmania”.

“Regardless of the resource burden and the challenges that Neil throws, we’re pleased to see him,” he said.

Local authorities have asked anyone who spots Neil to contact the marine mammal hotline. The public has been reminded to keep at least 20 metres away, keep dogs on a lead at least 50 metres away, and avoid blocking his access to water.

“We’ll keep an eye out for him but otherwise the traffic cones and street signs of Tasmania can breathe a small sigh of relief,” the Tasmanian premier, Jeremy Rockliff, said on Thursday.

“A big well done for everyone that has treated big Neil with respect and caution while he’s been on land.”