Contraceptives, not Slaughterhouse: Bison get birth control shots

Catalina is a small island, located 22 miles south, southwest of Los Angeles, and home to a non-native population of semi-free-range bison that were imported to the 74.98-square-mile island by a Hollywood film crew in 1924. The current herd members are the descendants of the original 14 bison that were to be extras in a movie that never went into production. Strapped for cash, the film company left them on the island where they thrived. Twice, to cull the herd which at one point numbered 600, the animals were sold to a bison auction house and shipped by barge and rail to the mainland where it is assumed they were slaughtered. The conservancy which manages the herd said their new strategy of providing birth control is cheaper and less stressful for the animals than having them shipped away to an unknown fate. The goal is to attain an ideal population of approximately 200 animals by reducing the annual population growth from 10 percent to four percent. The birth rate would then be about equal to their natural annual mortality rate, and is designed to ensure the health of the herd while protecting the island’s delicate ecosystem.

"We really are trying to find that balance between protection of the environment, restoration of the environment and the social and cultural values we believe are so important to our lives," said Ann Muscat, conservancy's president and chief executive officer. "And keeping the bison here is something our board found is important to the community."

Continuing, Muscat described the birth control program as:

"the sophistication in the management of the herd." next level of sophistication in the management of the herd."

From the Los Angeles Daily News: The contraceptive has been administered for years among deer, elk, wild horse and other bison populations. But Catalina's application of the vaccine marks its first use on a wild bison herd, said Dr. Jay Kirkpatrick of the Billings, Mont.-based Science and Conservation Center at ZooMontana, which has been training conservancy scientists since the summer. The porcine zona pellucida vaccine, when injected into the muscle of a female animal, stimulates the animal’s immune system. This produces antibodies, which attach to sperm receptors surrounding the bison’s eggs, preventing penetration, thus controlling the birth rate. Carlos De la Rosa, the conservancy's chief conservation and education officer, said:

…because it is not a hormonal vaccine, it won't cause them to change their behavior with their male counterparts.

"It's kind of like love without consequences."