A mother killer whale who famously pushed the body of her dead newborn for 17 days in 2018 has lost another calf, and researchers say she is again carrying the body.

Alive for 鈥渏ust a handful of days,鈥� the female calf known as J61 was confirmed to be dead on New Year鈥檚 Eve by researchers studying the endangered southern resident killer whale population.

The mother known as Tahlequah, or J35, has now lost two of her four documented calves.

Days before its death, it was reported the calf was believed to be premature. Concern was also raised about Tahlequah鈥檚 ability to successfully nurse a calf after it was noted she "appeared in subnormal body condition" in October.

While her last calf was born four years prior to J61, Brad Hanson, a research scientist for NOAA Fisheries Northwest Fisheries Science Centre, noted there is normally a five-year period between births.

鈥淪he may not have had time to physically recover from the prior calf,鈥� he said.

Similar to the behaviour seen in 2018, Tahlequah was observed on New Year鈥檚 Day with the dead calf 鈥渄raped across her snout鈥� or placed on top of the 鈥済rieving鈥� mother鈥檚 head.

The Centre for Whale Research says the death of any calf among the endangered southern resident killer whale population is 鈥渁 tremendous loss,鈥� but the latest is 鈥減articularly devastating鈥� because she was a female and because of J35鈥檚 history.

鈥淭his is an unfortunate way to start the new year,鈥� said Hanson.

With her attention focused on keeping her dead calf afloat, Hanson says the energy expenditure for Tahlequah is going to be 鈥渇airly significant,鈥� raising concern for her welfare.

鈥淥ne of the things that she's probably not having time to do is forage,鈥� he said.

鈥淎nd this is a time of year when fish availability is typically less than what it is other times of the year,鈥� he added.

While it was never observed directly in 2018, as there were 鈥渘o obvious signs of her deteriorating physically,鈥� researchers assumed other members of J pod were supporting Tahlequah through her 17-day grief procession by sharing salmon with her.

鈥淲hich is something that southern residents are known to do,鈥� said Michael Weiss, research director at the Centre for Whale Research.

This time around, according to Hanson, other members of J pod have been seen travelling with Tahlequah, taking an interest in her deceased calf, including her four-year-old offspring.

鈥淚t's hard to say whether or not they were actually helping to carry, but they were certainly engaged with her and curious about what was going on,鈥� he said.

Tahlequah鈥檚 sister, known as J53 who is now of reproductive age, was also seen 鈥渃onsistently鈥� travelling with the mother and deceased calf.

While they cannot be certain how she is feeling, experts believe Tahlequah is experiencing emotions connected to the loss of her calf.

鈥淚 think it's fair to say that she is grieving or mourning,鈥� said Joe Gaydos, science director for SeaDoc Society, who noted animals and humans can share similar hormones and neurotransmitters.

鈥淲e do see this behaviour in other animals, generally only long-lived socially cohesive animals, such as primates and dolphins,鈥� he added.

鈥淔rom a scientific perspective, if they have the same hard-wiring, they're gonna have the same emotions.鈥�

In contrast to the news of J61鈥檚 death, it was announced on the same day a new calf was seen travelling with the group known as J pod.

The sex and mother of the newborn calf have not yet been identified, but Hanson said they are 鈥渃autiously optimistic鈥�, noting it appears to be in a 鈥渧ery robust鈥� condition.

Orcas along the West Coast are categorized into three families known as the J, K and L pods, each of which has its own dialect and calls that differ from the others.

Fisheries and Oceans Canada and Parks Canada, in consultation with Transport Canada and Environment and Climate Change Canada, completed an assessment of the southern resident population last year, finding the population had dwindled to 73, with only 23 breeding females.

The Centre for Whale Research also said the population had dipped to 73 in its July 1, 2024 census following the death of two adult male orcas.

With files from The Canadian Press