The following are excerpts from

THE BIGHORN
Official Newsletter of the Bighorn Institute
From the Summer 2011 Newsletter

Augmentation Assists with Recovery
Bighorn Institute plays a vital role in the recovery efforts for the endangered Peninsular bighorn with its captive breeding and wild population augmentation program. As part of this program, in April, the Institute released two yearling ewes from the captive herd into the San Jacinto Mountains (SJM) near Palm Springs.

Prior to their release, both yearling ewes were ear-tagged, radio-collared and health tested. On the morning of April 20, 2011, with the assistance of Board member Michael Dee and Board veterinarian Dr. Roland Burbank, the yearling ewes were taken to Tachevah Canyon in the SJM. They were then flown by helicopter into an area near water and released. Both ewes were released without incident; unfortunately one of the ewes did not leave the release site and within a week had perished. Bighorn show incredible fidelity to their release site. The other yearling ewe has now been in the wild for three months. She has been observed in two canyons, which have resident ewe populations, and although she appears to prefer her independence, she is doing quite well. This ewe is being monitored daily for the first four months after her release and visual observations are attempted weekly.

Since 1985, Bighorn Institute has released 125 bighorn into the wild to supplement the bighorn populations in the SJM and northern Santa Rosa Mountains (NSRM). This number includes 99 bighorn born to the Institute’s captive herd and 26 that were born in the wild but rehabilitated at the Institute. Over the past 10 years, the Institute has focused most of its release efforts on the SJM, which has the smallest subgroup of all the Peninsular ranges. The SJM has struggled particularly with low ewe numbers getting down to just four adult ewes in 2002. Today with the Institute’s augmentation efforts, the SJM ewe population has risen to 18, of which 17 ewes, or 94%, were either released from the Institute or are the offspring of these released sheep.

Outside experts have suggested that the Institute’s captive breeding and wild population augmentation program has prevented two of nine subgroups of Peninsular bighorn sheep from extirpation, the NSRM & SJM. As each captive-born bighorn is released into the wild the recovery of this endangered species seems closer and more attainable. We are hopeful that this released yearling ewe will continue to thrive and ultimately contribute to the recovery of this endangered species.

 

Rutting 101
It’s that time of year again when the male bighorn sheep disperse from their bachelor groups in the backcountry and begin to search for females to breed. The breeding season, or rut, generally takes place from July to December for Peninsular desert bighorn. This is an exciting time because many of the unmarked rams are seen only during the rut. There are a number of large, beautiful rams in the Institute’s study areas and it is a treat to see them, especially as they go through their mating displays. There are several distinctive behaviors that are classified as “rutting behavior.” These range from the obvious, rams chasing and mounting ewes, to more discreet such as horn displays, low-stretches, and lip curls. A horn display is also known as posturing. Two rams size each other up by tilting their heads and displaying their horns to the other. Low-stretches involve the ram lowering his head and stretching out his neck and walking towards a ewe he intends to pursue. Typically, a lip curl often ensues. A lip curl allows the ram to sense whether or not a ewe is in estrous and receptive to breed, and entails the ram curling his top lip up. The most impressive and well known of all rutting behaviors is head-butting, which is essentially rams sparring over ewes for breeding rights. The dominant rams do the majority of the breeding so whoever wins these duels wins the ability to pass on his genes, which is the ultimate goal in the animal world.

 

Bighorn Crossing Highway 74
The central Santa Rosa Mountains (CSRM) encompasses the area south of La Quinta from Martinez Canyon to Deep Canyon along Highway 74. The northern Santa Rosa Mountains (NSRM) extend from the northwest side of Highway 74 to Palm Springs. The canyons on either side of Highway 74 are Deep Canyon and Carrizo/Dead Indian Canyons. Bighorn in the CSRM have been known to cross Highway 74 into Carrizo and Dead Indian Canyons of the NSRM, but over the course of the past few years we have documented an increase in utilization of these canyons by CSRM sheep. This is likely due to the growth in population of the CSRM subgroup, which results in the expansion of habitat use. The sheep broaden their range as their numbers increase. We are able to distinguish these sheep from the NSRM herd as most of the ewes have distinguishable horns and because there have not been any known ewes in this area other than a few the Institute has monitored over the past 10 years.

We are encouraged by this expansion in habitat utilization from the CSRM sheep, implying there may be an established group of sheep in Carrizo and Dead Indian Canyons. This would allow an increased gene flow and improved genetic diversity throughout the range. However, with the increase in movements across Highway 74, there have also been more bighorn/auto collisions. There have been a few sheep mortalities, but no human injuries. This is an issue that needs addressed with the wildlife agencies. A possible management solution to this issue could be to build an overpass for the wildlife, which has had success in other areas such as Alberta, Canada and Arizona.

 

Update: Cornishe of Bighorn
Cornishe of Bighorn is a development project adjacent to the Institute that could build 2 luxury homes on a 12-acre private parcel located just 240 yards from the Institute’s lambing pen. The homes will be within the 400-yard buffer zone that was established on nearby Canyons at Bighorn, to protect the captive herd of bighorn sheep from habituating to construction and urbanization. Cornishe of Bighorn does not have to abide by this buffer since it is a privately owned parcel. The close proximity of Cornishe of Bighorn could cause the captive herd to habituate to the point that they will no longer be fit to be released into the wild, thus thwarting recovery efforts.

In February 2009, the Palm Desert City Council approved the Cornishe of Bighorn Project. In March 2009, the Sierra Club and Center for Biological Diversity filed a lawsuit against the City of Palm Desert and California Department of Fish and Game regarding the City’s approval of the Project. In February 2010, the Sierra Club and Center for Biological Diversity filed another lawsuit against the California Department of Fish and Game for allowing the project to proceed without requiring a streambed alteration permit. The developer rejected all offers for negotiations and land-swaps.

This spring both lawsuits failed in court possibly leading the way for the development to begin. Appeals may be an option, pending funding, but it may come down to the U.S. Fish and Wildlife Service setting strict mitigation measures that will not fully offset the affects on the captive herd. While this is deeply disappointing, we remain hopeful for an appeal.

 

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