Bighorn sheep survey in San Gabriels set for March 1, volunteer slots filled
By JIM MATTHEWS
The Department of Fish and Wildlife (DFW) put out a call for volunteers to help in the annual count of bighorn sheep in the San Gabriel Mountains in mid-Febuary. In past years, the DFW was thrilled to get 150 volunteers who were scattered across the mountain range to help tally sheep. This year, the DFW closed off the list at 247 volunteers just the day after the solicitation went out.
“It’s great we have so much interest in our sheep,” said Jeff Villepique, the DFW’s long-time count coordinator. He said they would have enlisted more people, but they actually are now to a point where they have a shortage of crew leaders from the Society for the Conservation of Bighorn Sheep (a non-profit group), the U.S. Forest Service, and the DFW to guide small groups of ground counters into dozens of locations in the mountain range.
The count will take place on Sunday, March 1, and all volunteers will attend an orientation meeting the evening before. They will be broken up into small groups and given locations where they will look for sheep. A lot of hiking, climbing, and hillside-scrambling is involved to reach most locations, and then counters will patiently comb the surrounding hillsides with binoculars and spotting scopes.
The ground count will be held in conjunction with the DFW’s helicopter aerial survey. The counters will carefully count numbers, tally males, females, and lambs, and then plot their locations and time they were seen. This is done from both the air and ground. When double counted this way, the state agency is able to make very accurate estimates of the total sheep population in the range.
While the counts have been held annually since 1976, Villepique explained that the problem has been that coordinated counts have been impossible since 2011. This has prevented the DFW from making accurate population estimates. The weather has been the culprit. It has either been so foggy, rainy, or snowy that it prevented the helicopter flights, or recent storms made access to many locations difficult or impossible for ground crews.
“The indications we have is that the sheep population is going pretty well, but we’d really like to get in a solid count this year to verify the numbers,” said Villepique.
There are two primary factors that depress bighorn numbers – drought is one, but the lack of habitat-clearing fires in sheep habitat is critical. In the past three years, rainfall has been more normal and the long-term drought has subsided. There have also been a number of fires in sheep habitat that has opened up overgrown habitat, which normally leads to much higher survival of bighorn and high production of kids because of better habitat conditions.
The 2011 annual survey of bighorn sheep showed an increase in the herd of over 100 animals when compared to the last survey conducted under similar conditions in 2007, with a total of 418 estimated to be in the mountain range. The population estimate after the 2007 count was 308. The DFW believes the population is likely to be near those levels today, and Villepique was anxious to see the composition data (young to adult ratios) because it is a key indicator if the population is growing. In 2011, the count data showed an exceptional 52 lambs per 100 ewes, which is well above the long term average for the herd and the second highest on record. The high number of lambs surviving means the population was in a strong growth mode.
Biologists have tracked the bighorn population in the San Gabriels since the early 1970s, when the sheep numbers were much higher, averaging over 600 animals and peaking at well over 700 in the early 1990s. The population crashed that decade, dropping to as few as 100 bighorns throughout the range in 2000.
Villepique said fire is critical because it creates good habitat that grows younger, higher-quality forage for the sheep.
“If you burn it, they will come,” said Villepique in 2011. That year, he said they counted 30 animals on one small burned area on the East Fork of the San Gabriel River. Fires benefit sheep with improved forage conditions for at least eight to 10 years following the burn, but after that the shrubs mature and the volume and quality of available forage declines.
The late Steve Holl, a former U.S. Forest Service biologist and consultant, wrote the restoration plan for San Gabriel bighorn sheep herd in 2004, and that document is still used as a guide for restoring sheep habitat. Holl always said fire was the most important factor, and he was always critical of his own agency (the U.S. Forest Service) for not doing more controlled burns to help sheep. He pointed out that when the sheep herd was the most robust in the mid-1980s, the agency was doing more prescribed burns than it has done since. Holl wrote that “on burned ranges, the sheep population grows about four times faster than on unburned ranges. So clearly there is a relationship in population size to burned habitat.”
Jim Matthews is a syndicated Southern California-based outdoor reporter and columnist. He can be reached via e-mail at firstname.lastname@example.org or by phone at 909-887-3444.
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