Volunteer observers at the Vancouver Aquarium watch Qila the Beluga during the final days of her pregnacy last year. (John Healey/Vancouver Aquarium)

Aurora the 20-year-old beluga grandmother is getting ready to give birth again, staff at the Vancouver Aquarium say, and hundreds of volunteers are being organized to monitor the event.

Staff say they are making final preparations for the imminent birth, including signing up new volunteers for the aquarium's round-the-clock beluga observer program.

Nearly 200 volunteers will monitor Aurora, watching for signs of the onset of labour such as decrease in appetite, increase in dominant behaviour with other belugas, respiration rate changes and evidence of contractions.

Volunteers are also likely to be the first to see such signs of labour as Aurora's water breaking and the tail flukes of the unborn calf (beluga calves are typically born tail-first). It's fascinating to watch, beluga observer Pat Chapman said.

"It's incredibly interesting to watch Aurora and Tiqa [her granddaughter] interact these days. Aurora will be logging" — resting at the surface — "and Tiqa will kind of sneak up on her, get really close and then just stare at her. One night we observed this behaviour and saw Aurora snap her jaw in response to Tiqa!" Chapman said.

Already a grandmother

Aurora's first calf, Qila, was the first beluga whale to be conceived and born in a Canadian aquarium, in 1995. Her second calf, Tuvaq, was born in 2002 but died suddenly in 2005.

Aurora, Qila and Tiqa swim together at the Vancouver Aquarium. A new family member is expected soon. (CBC)

Her daughter Qila subsequently gave birth to her own calf, Tiqa, in 2008, an event that made international headlines and drew crowds to the Stanley Park facility after video of the birth was broadcast over the internet.

Tiqa, Qila and Aurora now share the Arctic Canada habitat pool at the Vancouver Aquarium. A fourth female beluga, Kavna, believed to be approximately 39 years old, resides in a behind-the-scenes habitat with the Vancouver Aquarium's 20-year-old male beluga, Imaq.