Ronan and I start an early moonlit ski up through Snow Pass to survey for moose in Gardner’s Hole
It has been a whirlwind since we last posted on the 22nd
of December. It seems that with the shorter days we have had to use every minute of daylight to get our moose surveys completed. We normally aim to start our early winter sampling on December 15th
and end on January 15th
, but this year we started early on December 13th
and ended on January 19th
. Since this is the third and final field season of our three-year study we wanted to make sure we thoroughly covered our study area. We will replicate this effort when we conduct our late winter survey during the month of April.
Snow fell just in time. A drop into the Gardner River
The snow started falling just in time allowing us ski access to all our survey areas. Without snow we would have had to conduct our work on foot and we would have needed another few weeks to complete our work. In total Lisa and I, with a few days help from friends Ronan Donovan and Emil McCain, sampled approximately 200 miles of study transects and collectively covered over 300 miles on our skis to do so.
That same day with Ronan skiing out with our headlights.
We collected a total of 134 moose pellet samples of 30 pellets each that we divided into 3 bags of 10 pellets each. One bag from each pellet sample will be shipped to our collaborator at the University of Minnesota-Duluth for genetic analysis and one bag to the Smithsonian Conservation Biology Lab in Virginia for pregnancy hormone analysis. The last bag will be dried in a large oven here in the Park by Lisa and I and 8 pellets from each sample will be measured to determine an average volume index of the pellets in order to assign one of three age classes to the moose that deposited the pellets (calf, yearling, or adult).
Collecting samples from a moose bed.
I am analyzing our individual moose ID’s (or genotypes) with a computer software program called Genecap. Each moose genotype consists of a sequence of 12 numbers which represents 6 different segments of DNA, each with a piece contributed by both the mother and father moose, called alleles. So 6 pairs of alleles for a total of 12 pieces of genetic information for each moose. Each individual in the population has a different combination of these 12 alleles. The software compares every individual genotype with all the others in the data set and combines groups that match and so are from the same moose (over the course of our surveys we will have collected samples from some moose multiple times). I have to make sure these matches make sense by comparing them to our other data; pregnancy hormone concentrations, volume of their pellets, and location sampled. After careful scrutiny I can generate a list of individuals in our study area. I’m not quite done with our first year analysis but at this point it is looking like we have between 80 and 100 different moose in our study area. After combining our 3 years of data I will eventually plug these into a Spatial Capture Recapture computer model to generate other population parameters. More on that in the future.
Highlights of our Early Winter 2015 survey included a New Year’s Day moose survey flight for me where I spent 3.5 hours flying over northern Yellowstone’s best moose habitat in search of moose and moose sign, a week in the beautiful Soda Butte Valley surveying the best winter habitat in our study area with the greatest concentration of wintering moose, and our 5-day back country trip up the Slough Creek drainage to its headwaters to look for moose in an area called Frenchy’s Meadow.
The ultimate goal of the moose survey flight is to locate moose and moose sign so that we can focus our surveys on those areas with moose. It also serves to eliminate those areas from surveying where no moose or sign is found. This is almost as important as finding moose because we can eliminate areas to sample that might otherwise require multi-day back country trips. I flew again in a Piper Super-Cub with pilot Steve Ard from Tracker Aviation out of Bozeman, MT. We found most of the moose sign where we were expecting to find it, in the upper reaches of Slough Creek, in and near Frenchy’s Meadow (FM). Each year we survey this area we find more moose than the year before and this year was no exception. In the willow flats two miles downstream from FM in an area called the 3rd Slough Meadow we located a group of 3 middle-aged bulls, on the south end of FM we located a bedded cow with a calf and young bull, and in the north east corner of FM we found a group of 6 moose bedded together, 4 bulls and two cows. One of the bulls had quite a large set of antlers and was a beautiful animal to see!
Three middle-aged bulls in the 3rd Slough Meadow.
We would later find the right antler of this nice Frenchy’s Meadow Bull
Our plans to start our FM trip the next day had to be changed and we would not be able to start until the 15th of January. However, I did not want to miss the opportunity to sample at least the 3 bulls we saw in the 3rd Meadow so the next day I skied 10 miles up the Slough drainage to where we saw them, collected their pellets that afternoon, stayed overnight in the Yellowstone Elk Tongue Patrol Cabin and then skied out the next day. We would have to wait to collect the other samples from FM for another 13 days. I was hopeful the snow wouldn’t fully cover their beds and tracks – I had taken pictures from the plane so that we could find them on the ground. By the time we did get to FM, six inches of snow had fallen but we were able to find the beds of each of the 8 moose I had pictures of and were able to collect samples from them all!
We look forward to our time in the Soda Butte Valley because we stay with our friends Laurie and Dan Lyman and get to visit also with friend and Wolf Project co-worker Rick McIntyre, a Yellowstone icon. The Valley is quite narrow with towering 9,000 to 10,000+ foot mountains on either side – The Thunderer; Baronnette, Abiathar, Meridian and Druid Peaks; Mount Hornady and Norris; and Mineral and Republic Mountains. Abiathar is the
Barronette Peak – Home of many Mountain Goats!
highest at just under 11,000 feet. Here we often find moose wintering 1,000 feet above the valley floor at over 8,000 feet where they hunker down for the winter beneath old growth conifer feeding on regenerating subalpine fir twigs and Old Man’s Beard lichen. The moose were plentiful but our surveys were challenging because the snow was still not deep enough to cover much of the downed trees and stumps and had the consistency of sugar, which made it difficult to move around in. Avalanche danger was high so we had to be very careful where we were skiing.
We look forward to the peace and solitude of Frenchy’s Meadow every year. Located 15 miles up the Slough Creek drainage from the trailhead, which is another 5 miles away from the nearest residents at the Tower Creek Ranger Station, the Meadow is the most
Skirting the 2nd Slough Meadow on the way to Frenchy’s Meadow
remote destination of our study. Over the last three years we have been the only ones to visit the Meadow in the winter and stay in the 1920’s vintage Slough Creek Forest Service cabin. FM lies within the Custer-Gallatin National Forest, a 3.1 million acre expanse that lies both north and west of the Park and is considered one of the most ecologically diverse landscapes in the region. Yellowstone of course is another but is only 2/3 the size at 2.2 million acres.
After a long day and 15 miles of skiing, Lisa approaches the Slough Creek Forest Service Cabin. Our home for the next 3 days. We hoped the key worked!
Slough Creek bisects FM and is joined by a number of other high mountain streams including Bull, Abundance, Frenchy, and Wolverine Creeks. Much of the lower half of the Meadow is formed by a huge alluvial fan at the outflow of Lost Creek. Choked with willow and pockets of mature conifer forest (most of the forest is regenerating lodgepole pine, still recovering from the massive forest fires of 1988) the area provides some of the best wintering habitat for moose in the region.
We sampled for a full two days here and were treated to some wonderful moose sightings and beautiful scenery. One day we were moving through the willow, continuously scanning for moose with our binoculars, when only a couple hundred yards in front of us
Using our track from the day before to push our survey to the top of Frenchy’s Meadow. This is near the spot where we saw the 4 bulls.
four middle-aged bulls popped up out of their beds. They regarded us curiously before moving off up the near slope where they watched us collecting their pellets. The next day we watched a cow with her bull calf, his little antler buttons just barely poking out of his head, feed along the east side of the meadow. Mom had for some reason decided it was okay to bed separately from the calf at almost 1/8 of a mile away so when we first saw her we thought she was alone. Soon we would see the calf meandering up the stream to meet
Lisa packing out our path to the outhouse.
her. On our ski out, in the 3rd Slough Meadow where I had seen the 3 bulls from the plane, we watched two bulls (one, the larger of the two had already dropped its antlers) feeding on the willows in the creek below us. We watched where they deposited pellets and then with Lisa keeping an eye on their activity I snuck across the creek and picked up my samples. They watched me curiously but were deeply engrossed in their mission of eating as many willow twigs as they could. Depending on the size of the animal and type of browse available, a moose can eat up to 60 pounds of forage a day!
Getting ready to depart the cabin, it always seems to snow while we are here.
We did find 2 moose antlers on our trip which are shed annually by moose. Change in hormone levels triggers the shedding of antlers. Those first to drop are from moose with the largest fluctuation in hormones. These would be the mature bulls that have the highest levels of testosterone during the late September fall breeding season. Young bulls can carry antlers into the late winter and in Vermont one year I even saw a yearling bull still with antlers in April. Only a couple of hundred meters from where I spotted the group of 6 moose from the plane on Jan. 1, Lisa found the right antler of the largest bull in that group. It was very distinguishable because it had a triple brow palm that was very obvious from my flight photo. Only 30
The first antler hung up in the willow.
meters from there and barely visible, I found another right antler from another mature bull. It was palm down in the willows with no tines sticking out of the snow. Had I been skiing 2’ to the left or right, I would have never spotted it. I may be biased, but I think antlers are one of nature’s most beautiful creations! Their individual shape, color, size and smell make each one so different from the other.
The antler in my left hand is from the large bull pictured bedded in the meadow.
Until next time from Yellowstone National Park, we wish you all well!