David Stein called Reptile Relocation Sydney last week after watching around six snakes slither into the mulch. He learned from an internet search that pregnant, known as gravid, red-belly blacks pile on top of each other before they give birth.

Reptile Relocation Sydney owner Cory Kerewaro said two of the captured adults gave birth to a total of 29 snakes in the bag while Cooper was still sifting through mulch catching more.

The final tally was five adults and 97 offspring caught, Kerewaro said.