Tahlequah, the Southern Resident orca who carried her dead calf for 17 days in 2018, is mourning the loss of another newborn, raising concerns about her health.

The calf was born Dec. 24. Observing researchers noted unusual unspecified behaviors by mother and calf that led them to worry for the young whale's health.

Tahlequah previously carried another dead newborn for 17 days in 2018. Here's what she's taught us about how orcas deal with death.