Yet another bighorn sheep relocated as part of an Arizona wildlife rehabilitation program was found dead this week, raising the number of animal deaths to 16 in just four months.

Since November, half of the original population of bighorn sheep relocated by the Arizona Game and Fish Department from Yuma to the Catalina Mountains north of Tuscon have died. Three mountain lions preying upon the sheep were subsequently killed by program organizers in an effort to reverse the tide, leading animal welfare groups to protest and question the efficacy of the entire effort.

After biological samples are collected and radio collars are attached, Doug Brimeyer, wildlife coordinator for the Jackson and Pinedale regions, releases a bighorn sheep ewe back into the wild Sunday, Jan. 26, 2014, outside Jackson, Wyo. Wyoming Game and Fish Department is acting as part of a multi-state effort to better understand what exactly is contributing to the death of so many bighorn sheep across the region. (AP/ Casper Star-Tribune, Ryan Dorgan)

After biological samples are collected and radio collars are attached, Doug Brimeyer, wildlife coordinator for the Jackson and Pinedale regions, releases a bighorn sheep ewe back into the wild Sunday, Jan. 26, 2014, outside Jackson, Wyo. (AP/ Casper Star-Tribune, Ryan Dorgan)

“The response to mountain lion killings of bighorn sheep has been to kill the mountain lions. That’s a mistake,” Ricardo Small with the group Friends of Wild Animals told Fox News. “When competition among mountain lions is removed, the litter sizes of the females increase and the result is more mountain lions than were there to begin with. I think that the Arizona Game and Fish Department should stop this program completely. It’s a waste of bighorn sheep and a waste of mountain lion.”

Department spokesman Jim Paxon told Fox News that groups shouldn’t necessarily worry about these mountain lion kills, because the population is “not only healthy, it’s thriving and expanding.” Even still, he noted that “conservation of wildlife is never easy, never quick and is often what biology professors call messy.”

The $600,000 three-year program, operated with public and privately raised funds, has already spent $150,000, which officials said is not from taxpayer money.

“The goal the Santa Catalina Bighorn Sheep Restoration Project is to restore a healthy, viable and self-sustaining population of desert bighorn sheep to the range that coexists with an equally healthy native predator population in a naturally functioning ecosystem,” Regional Supervisor Raul Vega said last year when the project was launched.

A female bighorn sheep is lowered onto a processing site for biological testing Sunday, Jan. 26, 2014, outside Jackson, Wyo. A helicopter wildlife capture crew was contracted by Wyoming Game and Fish Department to net ewes from a nearby herd as part of a multi-state effort to better understand what factors are contributing to the death of so many bighorn sheep across the region. (AP/ Casper Star-Tribune, Ryan Dorgan)

A female bighorn sheep is lowered onto a processing site for biological testing Sunday, Jan. 26, 2014, outside Jackson, Wyo. (AP/ Casper Star-Tribune, Ryan Dorgan)

Watch this video of the sheep release into the Catalina Mountain area in November 2013:

Even though the project would not appear successful thus far, Kevin Murphy, conservation director of the Wild Sheep Foundation, told Fox that conservation programs are “not a perfect, exact science,” adding that the success of this three-phase plan cannot be measured yet. 

Given the current issues with the relocated sheep and mountain lions though, wildlife department spokesman Joe Sacco said they might consider changing the release location going forward.

The area once had a large population of bighorn sheep, but it began to decline and nearly disappeared due to various factors in the late 1980s. The goal of the current program is to restore the population to at least 100 sheep.

n this Oct. 18, 2013 photo, a bighorn sheep stops after being released in the Santa Catlalina Mountains north of Tucson, Ariz. State wildlife officials addressed critics of its sheep-relocation project Friday, March 7, 2014 saying the effort could still prove successful despite the deaths of more than a dozen bighorns north of Tucson. (AP/Arizona Daily Star, Benjie Sanders)

In this Oct. 18, 2013 photo, a bighorn sheep stops after being released in the Santa Catlalina Mountains north of Tucson, Ariz. State wildlife officials addressed critics of its sheep-relocation project Friday, March 7, 2014 saying the effort could still prove successful despite the deaths of more than a dozen bighorns north of Tucson. (AP/Arizona Daily Star, Benjie Sanders)

According to the Arizona Desert Bighorn Sheep Society, three lambs have been born since the relocation of 31 adult bighorn sheep in November.