Bighorn sheep apparently have had their best month in the Catalina Mountains since 31 of the animals were transplanted to the range north of Tucson in November.
After 16 of the sheep died in the first four months following the release, no additional deaths have been confirmed since March 16, state wildlife officials said Friday.
Meanwhile, five bighorn lambs have been born this year in the Catalinas — and all apparently were thriving when last observed by biologists.
“We remain cautiously optimistic that the project will succeed long-term” in its goal of re-establishing a bighorn herd that disappeared from the Catalinas in the 1990s, said Mark Hart, spokesman for the Arizona Game and Fish Department.
The department and a citizens advisory group are overseeing the project, which has drawn support from some citizens and criticism from others who decry the deaths of the bighorns and the killing of three mountain lions that preyed on sheep.
“The lack of mortality over the last month is a good sign, as is confirmation of a fifth lamb birth and the apparent good health of the others,” Hart said. “We have seen all of the lambs in the field, apparently healthy, over the past couple of weeks.”
Global Positioning System collars have helped wildlife officers keep track of the surviving sheep and confirm that they are still moving.
“As far as we know, all of the remaining (adult) sheep are alive, and there are daily monitoring efforts to confirm this,” Hart said. “With that said, we do have one collar that may have malfunctioned, and because of the remote location we are currently unable to confirm the sheep’s status.”
Also unknown is the status of a yearling ram, the only one of the 31 sheep transplanted from the Yuma area that wasn’t fitted with a GPS collar.
“As you can imagine, without a collar it is difficult to get anything more than an incidental sighting,” Hart said.
Collar batteries are expected to last about two years. Each collar has a release mechanism that will allow it to drop off the sheep at the end of the battery life.
Is it possible that killing of bighorns by mountain lions might have decreased significantly with the killing of the three lions that were found to be preying on sheep?
Joe Sacco, wildlife manager supervisor for the Game and Fish Department, and Hart responded to that question with this written statement:
“Lion predation has gone down from previous months, but the cause and effect cannot be directly tied to the removal of the three lions as there are so many variables that influence predation. With that said the mountain lion management plan was developed to remove those lions that have taken sheep and leave in place those that do not.”
It goes on to say, “From observations of tracks in the area we can conclude that lions remain in the area while predation has dropped off. It would be naive for us to believe that there will not be further predation events and therefore we will continue to remain vigilant and implement the mountain lion management plan when appropriate.”
Sacco and Hart emphasized that it’s too early to view the project as a success or a failure.
“Reintroduction effort success is measured over years, perhaps decades, not months,” they wrote. “It is important to understand that populations rarely flourish immediately and that active management is required.”
A CITIZEN’S VIEW
“The Arizona Fish and Game Department should be congratulated on a job well done,” said Leon Munyan, a hunter and conservationist. “If they continue lion predation control, and if hunting conservation organizations continue their support of the project, reintroduction of the sheep should be successful in the long run.”