Sick and dead birds are continuing to wash up along two Winnipeg retention ponds, but Wildlife Haven Rehabilitation Centre is sharing some good news.

It released four shore birds it’s been caring for back into the wild Wednesday afternoon.

“When we got them in they were quite weak, a little bit lethargic, starving, so we brought them in,” said executive director Zoe Nakata. “Number one is to take them out of the toxic area, so that’s the most important part of their treatment and we got them soon enough that we were able to rehab them.”

Nakata said the birds were given lots of fluids and they were able to stabilize them, helping them build up their strength for release.

READ MORE: Residents want answers as dead animals litter Winnipeg retention pond

The four shore birds released Wednesday were picked up from a retention pond in the Amber Trails area Friday and Saturday.

Nakata said over the past few weeks Wildlife Haven has received anywhere from six to eight sick birds daily. They’re coming in from the retention ponds on Bitterfield Road in the Amber Trails area and Adsum Drive in the Mandalay neighbourhood.

“Unfortunately, it’s not always such a good outcome,” said Nakata. “A lot of them are passing away before we get to stabilize them, so that’s why were quite excited that this small batch has made it.”

She said they are hopeful the other birds in their care will also make a full recovery, but what’s causing their illness is still unknown.

“We know that it’s something in the water that’s affecting, as we’ve seen a lot of shore birds and ducks and pelicans, but we’re still waiting on word from the city to see exactly what it is.”

READ MORE: Dead animals washing up at Winnipeg pond

On Monday, Dan Diawol with Wildlife Haven said they counted more than 30 dead ducks at the Amber Trails location alone.

The City of Winnipeg told CTV News in cases where a number of birds or wildlife are found deceased, the city will work with the Chief Veterinarian’s Office to determine the cause by submitting samples of the dead animals for testing.

The province said the exact cause of death has not been confirmed, but a possibility includes botulism, which can occur naturally in ponds like this. It said botulism outbreaks are common in the summer, and during extended periods of hot weather blue-green algae can develop which has also been known to cause fish and bird mortality.

The city said staff are monitoring water quality at retention ponds, as well as removing dead animals.

Winnipeggers are reminded not to handle dead or dying wildlife, and to keep their pets out of the water. The city said injured or dying wildlife should be reported to the Manitoba’s Sustainable Development Department - Wildlife Branch, and dead wildlife can be reported by contacting 311.