Animal Alliance of Canada and Zoocheck Canada say mother bears will be killed during the hunt, leaving their orphaned cubs to starve or be killed by predators.
"The babies at this time are very small," said Julie Woodyer of Zoocheck Canada.
"This is the only large game species that are hunted when the young are still dependent on their mothers and it is inevitable that cubs will be orphaned."
The animal rights groups have filed an application for judicial review and a notice of constitutional question, which are set to be heard in court on April 29, just days before the start of the program. They hope the court will at least delay the start of the hunt until it can rule on their legal actions.
The regulation would be contrary to animal cruelty laws in the Criminal Code, said the groups' lawyer David Estrin.
"In our view, reinstituting this program would be tantamount to the minister and the Ministry of Natural Resources either wilfully permitting bear cubs to suffer or failing to exercise reasonable care or supervision of the bear cub population," he said.
"The Criminal Code prohibits causing or allowing animals to suffer. This program of the Ontario Ministry of Natural Resources will cause black bears to suffer."
The pilot project to reinstate the spring bear hunt will start May 1 and run for six weeks in eight wildlife areas known for having the most public safety incidents involving bears.
"In northern Ontario it is not responsible for a provincial government to ignore the concerns of thousands of residents who are concerned about their public safety," said Natural Resources Minister David Orazietti.
"We have young children who can't go out for recess at their schools, teachers wearing bear whistles because their children are threatened."
Nearly 50 mayors and city councils across northern Ontario have passed resolutions calling for their participation in the program, Orazietti said. Out of 95 wildlife management units in Ontario, the pilot program will be in eight, he said.
"Some people who are completely unaffected by this issue and whose children may be perfectly safe in the schools that they attend have no understanding of the implications and the safety challenges in communities in northern Ontario," Orazietti said.
The hunt was cancelled in 1999 and then-natural resources minister John Snobelen said it had left thousands of cubs orphaned since hunters too often mistakenly shoot mother bears.
"Really, the only answer we came up with was to end the spring bear hunt," he said at the time. "It's the only acceptable way."
Orazietti said the government has learned over the past 15 years that other strategies to reduce human-bear incidents have met "fairly limited success."
"This has been a very, very thoughtful and strategic approach," he said Thursday. "We're not suggesting a return of the spring bear hunt of yesteryear."
The animal rights groups say the ministry's own scientists have found no link between the end of the spring bear hunt and human-bear incidents. Orazietti said "that's not completely true."
"Our scientists do recognize that there are other scientists and other groups that have indicated that bear hunts do in fact have an impact on population," he said.
Terry Quinney, the provincial manager of fish and wildlife services for the Ontario Federation of Anglers and Hunters, said the spring bear hunt was for decades a valuable wildlife population management tool.
"In reducing the density and distribution of bears in the spring, particularly those older male bears, it is absolutely reducing the probability of dangerous encounters with people," he said.
Hunters target the male bears, Quinney said, and there are ways they can distinguish male and female bears, especially using suspended bait.
"It's not hard to imagine that if a food source is placed, for example, hanging from a tree, a bear in order to reach that food source is going to stand on its hind legs, making its genitalia very visible to a hunter," he said.
Quinney also said there would be economic and social benefits to re-establishing the spring bear hunt in northern communities.
"Prior to the cancellation of the spring bear hunt in Ontario there were approximately 600 family-based businesses in northern and central Ontario that were involved in the spring bear hunt, for example providing guiding services for hunters," he said.
"Revenues to northern and central Ontario on an annual basis were in excess of $40 million a year. All of those economic benefits have disappeared from Ontario."