A grieving mother orca whale is falling behind the rest of her family after carrying the corpse of her calf a week after it died.

Experts at the Whale Museum on San Juan Island have been monitoring the 20-year-old killer whale, known as J35, since her calf died shortly after she gave birth last week.

Since then she has been balancing the dead calf on her forehead or pushing it to the surface of the water.

Jenny Atkinson, the museum’s executive director, said the orca was spotted still carrying her dead calf almost six days after she lost her child.

She told The Independent the mother was falling behind the rest of the family as it went through “a deep grieving process.”

Ms Atkinson said during the day the whale appeared to get weaker, but seemed to find renewed strength overnight, showing a “more normal swim pattern in the morning.”

The mother pushed the dead calf to the surface on her forehead (David Ellifrit/Center for Whale Research via AP)

But she also said the whole family appeared to be taking part in the grieving process.