The film has earned an animal safety acknowledgement from watchdog group the American Humane Association, but People for the Ethical Treatment of Animals (PETA) officials have discovered as many as 27 creatures were killed on a farm near Wellington, New Zealand, where they were housed in between takes.
Four animal wranglers have come forward to alert PETA bosses to poor conditions on the farm and incompetence that reportedly led to the deaths of three horses and numerous sheep, goats and chickens.
The animal rights activists have now ruled all the deaths could have been prevented if Jackson's lead trainer and the head of production had "fulfilled their duties and heeded the warnings of several wranglers".
PETA Senior Vice President Lisa Lange tells WENN, "Two horses were run off embankments and sustained broken necks on the set of The Hobbit, at least one horse was left lying on the ground with his legs tied together for more than three hours, numerous goats and sheep used for the production died from worm infestations and from falling into sinkholes, and a dozen unprotected chickens were killed by dogs.
"Peter Jackson's films have been at the forefront of the special-effects revolution, but this production's decision to use numerous live animals and allow them to suffer needlessly and die takes the entertainment industry a giant and disgraceful step backward."
Among the whistleblower allegations outlined in PETA's letter to Jackson: one horse was euthanized, and another was found dead with her face submerged in a river; a horse named Zeppelin died, likely of colic, after his diet was suddenly and drastically changed, and the production's American Humane Association representative was not present for many of the animal sequences.
PETA executives, who plan to protest the film at each of its premieres in the U.S., U.K., and New Zealand next month (Dec12), also claim that one wrangler was allegedly fired for expressing his concerns.
Jackson has yet to respond to the letter, but a spokesman for the film has told the Associated Press than some of the deaths were from natural causes.
The rep, Matt Dravitzki, also agreed that the deaths of two horses were avoidable, and said the production company moved quickly to improve conditions after they died.