I was following behind a truck into the parking garage one day and when I got out of my car, a strong smell of diesel permeated the whole level. I immediately flew back in time to Morgan Creek and my sheep. See, jet fuel smells a little like diesel and whenever a vehicle goes by me that uses diesel fuel, I get 1) a little disoriented (I suffer from motion sickness, so you can imagine what I felt when flying to locate my sheep) and 2) a twinge of nostalgia for my life in Idaho.
Note that the twinge is not enough to make me want to live there again – it was a hard life on the edge of the wilderness area – bitter cold in the winter with difficult travel (vehicle or hiking) through the piles of snow, and extremely hot and arid in the summers.
Being so far from other people is enjoyable, but also scary at times. You only have yourself to rely on. I carried a Forest Service radio for emergencies (there was no such thing as a cell phone back then), but even that didn’t reach up and out of some of the places I was in, particularly when my fuel line froze one day when I was deep in a canyon in the dead of winter. I had to rock-climb up the snowy, frozen canyon wall to get high enough for the radio signal to reach up and out to a repeater tower. It was then another hour before help arrived in the form of our local Conservation Officer, so Lacey (my dog) and I were pretty cold by then.
I, of course, carried a backpack everywhere, which included a flashlight, a knife, water and a sealed waterproof match container. It was also important to have chains for your vehicle tires at all times. These precautions were necessary for anyone traveling backcountry like I did – being stuck in the snow and possibly freezing to death may seem far-fetched for many city-dwellers but it is a real concern (Idaho-town-mourns-girl-who-froze-to-death-on-Christmas-Day).
To continue my post from several years ago, I tracked my radio-collared sheep for two years. Each of those two winters, we captured some sheep, radio-collared them and moved them to another area to augment outlying populations. This helped provide additional genetic variation into these populations, which in the past would have been accomplished by sheep immigrating naturally from one area to another (see map). And in both years, when we examined some of the sheep we captured, we deemed their body condition to be too stressed to take the risk of moving them. These stressed sheep were radio-collared and then released on site, back into the Morgan Creek population so I could follow them for my study.
As I tracked where these sheep went on my study area (and into the River of No Return Wilderness Area during summer), I marked their locations on a topographic map. Using this I could determine the overall population’s “range” and each individual sheep’s range and movements.
Bighorn sheep migrate from their summer breeding range high in the mountains down to lower elevations, known as their winter range, beginning in Fall. Lower elevations have warmer temperatures and less snowfall. On the warmer southern slopes of the mountains in their winter range, they can more easily paw through the snow to find vegetation to eat.
Young sheep stick with their mothers and learn the migration path from them as they grow up. Eventually, the young rams begin to venture out on their own and meet up with other rams, forming bachelor groups. However, the young ewes stay with their mother’s group for life, which means they will end up following the same path their mother taught them.
Young rams however sometimes join up with a ram group that is traveling a different migration path and these young rams end up following their route instead. I had at least one of my young rams do this. He left Morgan Creek and headed with a larger ram group up to Cronk’s Canyon, quite a few miles from where his mother’s group lived.
When the snow begins to recede and grass and other vegetation begins to green-up at higher elevations as spring and summer progress, the sheep follow the greening plants back up into the higher elevations where they are then ready when breeding season begins. They follow their own learned paths at this time. Once the rams reach their summer range, they find ewe groups and the rams compete for dominance. I imagine most people have heard of how they butt each other as they try to determine who is dominant and gets breeding rights for a ewe group.
There are times when this becomes dangerous, as sheep tend to be on cliffs which can lead to accidents. Sometimes it would be difficult to find one of my radio collared sheep so I would triangulate their location. I would take locations from several areas and draw the direction I was receiving the signal from my compass onto a map and where the lines intersected would be marked as the sheep’s location. When I was tracking one of my collared rams this way, I could tell he hadn’t moved in several days and I figured something bad had happened to him. After a couple days of searching, I found him at the bottom of a cliff, apparently having fallen to his death, possibly during a head butting incident.
known as annuli, on its horns. He fell from a cliff to his death.
The bighorn sheep population in my study area were at historic high levels during my 2-year research project, even with the poor health of the animals due to overcrowding on the winter range (see my first post). After completing my project and moving to Michigan to continue my education there, I continued to check on the population surveys the Fish and Game Department conduct on a regular basis. The population count in 1988 was 278 total sheep. By 1991, it appeared that the population had dropped by almost half. While that seemed alarming, the winters were milder than normal those years, resulting in less snow depth. When counting sheep, we would fly in a helicopter throughout the winter range, and the snow helps to 1) keep the sheep on southern slopes and more congregated, and 2) make the sheep more visible against the white background. Because of less snow, we did think that perhaps since we hadn’t seen a lot of dead sheep anywhere and I lost only one collared animal to death – this seemed to support the idea that the population had not really dropped so much. Instead, we believed that we had just missed some sheep in the counts.
However, from 1990 on, the bighorn sheep populations in the area experienced high mortality of both young and adult sheep, apparently due to disease. Bighorn sheep suffer from things like Pasturella Haemolytica, a bacteria that causes severe respiratory disease, lungworms which infect the lungs and cause pneumonia, Brucellosis, which causes spontaneous abortions in pregnant ewes, and other diseases.
Lamb production for several years after my study ended was very low (less than 10 lambs per 100 ewes). This, accompanied by the high disease levels, caused a large population drop that has persisted at least until 2018 (the latest report I could find online). The population now seems to hover right around 100 sheep, about one-third of what it was when I did my research. The good news is that the most recent estimates show that the productivity has climbed back up to about 30 lambs per 100 ewes, which helps the population be more stable. This also indicates that disease levels are lower now than they were when I studied the sheep there. Hopefully, they will remain healthy for many years to come. This was probably the most amazing wildlife research I ever did in my career.
Gina Karasek 