Six massasauga rattlesnakes were born at the Toronto Zoo as part of the organization's conservation breeding program.

In a statement on Wednesday, the zoo said the snakes had hatched on Aug. 16, and are doing well. A second female also gave birth to several snakes Wednesday morning, the statement said, though officials were unsure exactly how many snakelets were born.

The zoo said the young snakes will soon join the zoo's population of adult massasaugas.

The births are the second success story in the zoo's massasauga breeding program. Massasauga rattlesnakes are an endangered species in southern Ontario, and are "a challenging breed to reproduce," the zoo said.

Their population is threatened by loss of habitat and vehicle traffic.

The snakes are part of a species survival conservation plan that began in south of the border in 2006, as a result of concerns over the decline of the populations in Canada and the U.S.

"We are very excited to see success, for a second year in a row, of this important conservation breeding program," Curator of Reptiles and Amphibians Andrew Lentini said in a statement.

"This birth gives us confidence that we are making major strides in the work we are doing that will sustain recovery efforts for these special snakes now and for years to come."