Heather Cassels was in disbelief while cycling down Bayview Avenue south of York Mills Road last Thursday when she saw that workers were cutting down a grove of trees near her home.

"I stopped because I was shocked to see so many trees coming down," she told CBC News. "And when I came back from the cottage Monday, these huge trees here were down."

The city said it is investigating after a developer cut down 30 trees, many of which were over 100 years old, on both sides of Bayview Ridge at Bayview Avenue.

Cassels said she asked the site manager if he had a permit and was told that he did.

Residents in the Bayview Avenue and Bayview Ridge neighbourhood are upset that a developer cut about 30 century-old trees to erect homes on the land. (CBC)

"I said, 'I can't believe the city would give you a permit to cut down so many trees,'" she told CBC.

Cassels said she contacted Coun. Jaye Robinson, who represents her ward, and was informed the developer didn't have a permit to cut down the trees.

Format Group is developing what it calls "an upscale community comprising of two blocks of exquisitely appointed homes." On its site, it claims that it is "known for masterfully developing luxurious communities and one-of-a-kind custom homes that seamlessly fit into the fabric of the community."

Format Group's Sina Saedin said his company needed to clear the land to make way for new townhouses and homes and that he acquired the necessary permits.

But a spokesperson for the city said it didn't issue Format Group any permits.

The city said it is investigating the clear cutting and said Format Group could be fined $100,000 per tree.

Cassels said she's hopeful the developer will be held responsible.

"You got to start somewhere and tell the builders they can't be taking down trees."