Educational Bulletin Spring 2016

8/17/2019 Educational Bulletin Spring 2016

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Educational Bulletin #16-2A publication of the Desert Protective Council protectdeserts.org

On a brilliantly clear February morning, I sitquietly on the saddle o a ridgeline looking throughmy spotting scope at a group o bighorn sheepbedded on the opposite slope. So ar I’ve counted 6ewes (emales) and a couple o lambs napping neartheir moms. Fortunately, I’m ar enough away thatmy presence has not caused them to get up and moveaway. Tis group does not know it has a “Judas ewe”among them, allowing me to find them in this remotecorner o the desert. Ewe 292 sports a collar that emitsa radio signal I have tracked to this location using a

hand-held receiver and directional antenna.Desert bighorn sheep that reside within thePeninsular Ranges o Southern Caliornia wereederally listed as an endangered segment o thepopulation in 1998 due to a number o actorssuch as habitat loss, habitat ragmentation, humandisturbance, and disease introduced by domesticlivestock. As a wildlie biologist working or theCaliornia Department o Fish and Wildlie (DFW),it is my job to document habitat use and movementcorridors, estimate population abundance, andmonitor the health, reproduction, and survival othese sheep. In order to accomplish these objectives a

representative sample o the sheep population withinthe Peninsular Ranges is captured and radio-collared

While DFW has monitored sheep or over 20years, it has only been in recent years that we havebegun to fill in the gaps in our understanding o ewegroup structure in several areas o the PeninsularRanges. We define a ewe group as a discrete groupo ewes that share the same areas or raising theirlambs (lamb rearing habitat) and or obtainingwater during the hot summer months. Ewe 292was one o several sheep captured just north o the

Peninsula Bighorn Sheep by Janene Colby, Wildlife Biologist

Valley of Fire State Park, Nevada. Photo by Terry Weiner

Photo by Jeff Young


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US/Mexico border in the all o 2013. GlobalPositioning System (GPS) location data rom theseradio-collared sheep as well as direct observationshave provided us with invaluable inormationconcerning ewe group structure and movement acrossthe international border. As I wait or ewe 292 tostand up so I can see i she has a sleeping lamb tuckedbehind her, I think about all the challenges ewes ace

in providing enough nutrition and protection or theirgrowing lambs in a harsh desert environment. Andadded to all the natural challenges aced are thoseimposed by human disturbance and encroachmentwithin the desert landscape.

Tis group o ewes, dubbed the “Jacumba EweGroup” lives in an area o approximately 45 squaremiles between Highway 2 in Mexico to just south oInterstate 8 in the United States. Tese ewes spend thehot summer months in Mexico within a ew miles owater sources. Presently, there is not a ence along thissection o the border, allowing sheep to reely travelnorth across the border to pre-lambing and lamb

Photo by Jeff Young


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rearing habitat within the Jacumba Wilderness in theUnited States.

Tis wilderness area, managed by the Bureau o

Land Management, is a Wilderness in name alone as ithas an extensive system o dirt roads that are used bythe U.S. Customs and Border Patrol. Border securityactivities include regular vehicle patrols, oot patrols,horse-mounted patrols, and helicopter flights bothnight and day within lamb rearing habitat. Directlyeast and adjacent to the wilderness area is a Wind-Energy Facility. Any additional energy developmentswithin or adjacent to this area combined withdisturbance by border security activities may havesignificant adverse effects on this ewe group. Tis vitallamb rearing habitat is not within the current U.S.

Fish and Wildlie Service’s (USFWS) 2009 RevisedFinal Critical Habitat (74 FR 17288). Tis may be agood time or USFWS to “revise the revision” andreinstate the original 2001 Final Critical Habitat (66FR 8650) which included all essential sheep habitatwithin the Peninsular Ranges.

I look through my spotting scope and see that ewe292 continues to rest quietly as she chews her cud,so I turn my thoughts to the problems aced by theIn-Ko-Pah ewe group directly north o the Jacumbaewe group. In 2009, a group o ewes and rams werecaptured just north o Interstate 8 and fitted with solarGPS radio-collars. In the transition rom the desert

to the mountains, the west-bound lanes o Interstate8 wind up through Devils Canyon while the east-bound lanes pass down through In-Ko-Pah Gorge;this divergence creates an approximately 7 mile by 1.5mile island surrounded by the Interstate. Te In-Ko-Pah ewe group spends the hot months o summer andearly all within a ew miles o a spring located northo the Interstate. As the weather cools, and vegetationsurrounding the spring has been depleted by monthso heavy use, the pregnant ewes move back and orthacross the west-bound lanes o Interstate 8 withinDevils Canyon in search o adequate amounts oorage. ypically, ewes move into the north section o

the Island where the majority o radio-collared ewesgive birth each year in an area outside o designatedcritical habitat. In February during the peak o lambrearing season, a nursery system is ormed on thewarm southeast acing slopes overlooking the south-bound lanes o the Interstate.

Sadly, I can observe ewes and their lambs whilesitting in my truck on the shoulder o the busyInterstate. I ofen find mysel holding my breath as

I watch one ewe remain on the slope with the lambswhile the rest o the ewes move down-slope andorage in the low-lying areas o the canyon alongsidethe Interstate. Alongside the shoulder o the roadwhere plants grow larger and greener due to rain run-off, ewes consume plants greedily in order to meet thehigh energy demands during lactation.

Each year, several non-collared sheep are struck andkilled by vehicles along this stretch o the InterstateFortunately, since 2009, only one radio-collared ewehas been struck and killed while attempting to crossthe east-bound lanes. In act, several radio-collaredewes cross the east-bound lanes numerous times

a day during the first month o the lamb rearingseason. Obviously, sheep do look beore crossing theroad. Eventually though the Interstate will becomean impenetrable barrier as traffic volumes increaseeach year.

As a wildlie biologist, it is hard not to becomediscouraged. But, sheep numbers have increasedand stabilized since Federal listing in 1998, possiblydue to a variety o measures including removal odomestic livestock that spread disease to wild sheepland acquisition and protection in some critical areasand removal o non-native invasive plant species that

deplete natural water sources or sheep. Lying within

Photo by Miguel Lizarraga

Photo by Jeff Young


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the heart o sheep habitat is Anza-Borrego DesertState Park (ABDSP) with approximately 400,000 acreso state wilderness area. ABDSP is a stronghold orsheep; however, connectivity to the north and southo the Park needs to be protected in order to maintaingenetic diversity and population viability. Te longterm health and survival o bighorn sheep dependson protecting and maintaining intact wildernessareas that allow sheep to adjust their movements

in response to changes in resource availability andclimate change. All gains in sheep recovery will be ornaught i aced with continued highway expansion,border ence construction, and habitat loss due tourban developments and renewable energy projectswithin sheep habitat.

I am roused rom my thoughts by the sound orocks rolling down the opposite slope. Te ewes havefinished their morning nap and are starting to eedand move across the slope. I quickly look through myspotting scope just in time to see a small gray lambrun up to ewe 292, latch onto an udder and start tosuckle. Te lamb waggles its tail while bumping the

ewe’s udder to increase the flow o milk. Te ewe turnsher head and lightly touches the lamb’s tail with hernose, once, then twice, as i to confirm that indeedthis is her lamb and it is sae and healthy—all is good.Yes, I think, i as a society we care enough to protectand preserve what wilderness remains, there is indeedhope—all will be good.

Passage from a biologist field journal:

In my pursuit o tracking sheep, I have the uniqueopportunity to step into wilderness areas that ew

people willingly choose to go. For here in this hot, un-named canyon wash, there is no lofy peak to climb, nodesert palm grove to sit beneath, no mapped culturalsites to seek. It is in these quiet places that wildlie can go about the daily business o survival. I take a breakand sit in the shade. All is still. I absorb the eatureso the canyon. Te rich, red, sunbaked patina on thelarge stacked boulders creates shapes and shadowsmore beautiul and elegant than by the hand o themost creative sculptor. As I become just another eatureo the landscape, the animals start to appear rom theshadows. An antelope ground squirrel runs by andscurries up to the top o a barrel cactus and vainly

attempts to pry loose a at, seed laden ruit. I hear thehigh pitch whirr o a hummingbird, the call o a male phainopepla attempting to attract a mate as he sitsatop a nearby catclaw. A whiptail lizard passes beneathmy eet in pursuit o a tasty insect. Its long tail slices atrail in the sand. Just beyond I catch sight o resh sheeptracks. A light smell o desert lavender wafs down thecanyon on a very warm morning breeze. Tese quiet places, where the natural world reigns, are harder to find—the loss weighs heavy on my soul. Ten, I hear arock all…I think there are sheep just around the nextbend!

Special Note

Tis article is based on the field experiencesand insights o biologist Janene Colby and doesnot represent the official views o the CaliorniaDepartment o Fish and Wildlie.

For Additional Information

Desert Bighorn Sheep: Wilderness Icon offers a glimpseinto the lives of the elusive desert bighorn sheep: their habits,

their social lives, and their natural habitats. It is written forthe general reader in a casual and engaging writing stylethat contains enormous amounts of fascinating informationwithout feeling like a science lecture.

Author Mark Jorgensen has served as a state park rangerresource ecologist, and superintendent of Anza-BorregoDesert State Park in his 36-year career in California StateParks. He has spent 5 decades studying desert bighornsheep and is clearly dedicated to sharing his love for andunderstanding of these amazing animals.

Within the pages you will find Photographer Jeff Young’smost comprehensive photographic work assembled into whatis the finest collection of desert bighorn photos ever published

Te book features some 200 high quality photographsfeaturing rare behavior, sheep in their rugged desert habitatewes nurturing newborn lambs, and massive rams instunning ritualized combat for dominance.

Educational Bulletin Spring 2016

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