Maternal Penning Update June 30, 2023



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Pen update
As calf birthing season draws to a close, it is hard to believe that we are already two thirds of the way through the penning season! At the time of writing, there are 37 caribou in the maternity pen on Mt. Bickford. This is the most that we have ever had in the pen – and more than the starting population of the whole herd in 2014! While this is a very positive statistic, it also means that the Caribou Guardians are busier than ever keeping track of this ‘mini-herd’ inside the pen. Daily checks require that guardians visually locate every single animal once a day. Spotting the caribou, and especially young calves, is not always easy! To try your hand (or eye) at being a Guardian, see how long it takes you to find the calf in Figure 2. The Guardians also feed the caribou twice a day, manually carrying roughly 50kg of pelleted feed to six troughs every morning and evening. Maintaining the integrity of the geotextile and the electric fences is key for ensuring the safety of the cows and calves, so Guardians must circle the entire pen twice-daily and check for any ‘weak spots’ or damage, and promptly address any issues that they notice.

Predator activity near the pen this year has been very low based on sightings, tracking and trail camera captures. We did record a lone wolf on Fisher Creek Roads in April – a trail camera near the bottom of the hill captured it heading south, but there have been no signs of this wolf or any others on Mt. Bickford in the last two months.

Calf 38, who was born in the pen last year (2022) and orphaned upon his mom’s death shortly thereafter, has been seen on surveys with a large and ‘tight- knit’ group of caribou consisting of male and female adults as well as other juveniles – his ‘age mates’ from the 2022 calving season (Figure 4). This is the same group that he has been with since October 2022, and at present they are spending most of their time on a small mountain close to Mt. Bickford. In contrast to his generally small size in the fall and spring, 38 has grown and is now on par with his peers.

This year has seen the most calf births in the pen and among the free-ranging population since the start of the project. In the pen, 21 of the 22 adult cows were pregnant at time of capture in March. One of the cows, a two-year-old wild born female, had a late-term miscarriage on April 23. The fetal calf was very tiny; we will be sending the body away for necropsy upon completion of the penning season. Another pregnant cow unfortunately died in the pen, a few days after giving birth. Of the remaining 19 pregnant cows, 18 delivered live calves (with one more expected). Among the 22 collared free-ranging cows, we have confirmed 20 live births via aerial surveys.

The timing of calving this year was more clustered than we have observed for the past few years. Of the 38 calves born so far this year, 29 were born in the fortnight between May 15th and May 29th, thirteen of whom were born in the three-day interval between May 22nd and 24th. While this start to the birthing is later than is historically typical for caribou in the area, the clustered pattern is more in line with our observation of local mountain caribou. It is also worth noting that the free-ranging cows had tighter clustering of calving dates than the penned cows, for reasons we are still looking into.

Calf sex ratios

This year we saw balanced sex ratios among the calves born in the pen, which was a welcome return to more even numbers after the male bias seen in pen-born calves between 2020-2022. Nine males and eight females were born in the pen, plus the miscarried calf, which we were not able to sex. Among the free-ranging calves that we were able to capture and/or sex using aerial photos, there were eight males and eleven females and one of unknown sex.

In our wild calf capture and collaring program, we made important modifications to the protocol based on experience gained last year. Most importantly, we decided to not capture the calves of ‘high-risk’ cows i.e. ones that are young and therefore likely first-time moms, as well as cows that have a history of abandoning their calves. This year, this translated to three cows that were deemed ‘high-risk’. Three other calves were either too old or in unsafe positions for capturing so they were not collared either. The remaining fourteen calves that we captured and collared reunited seamlessly and quickly with their mothers (Figure 7). One interesting case was a free-ranging cow who calved very close to the boundary of Bocock Peak Provincial Park; about 150m away from her, on the other side of the ridge, was a group of five mountain goats, using basically the same habitat.

Rochfort maternity pen post-operation restoration

Last summer (2022), a small crew went up to the previously used Mt. Rochfort maternity pen site to do some restoration work. As a result of the caribou living inside the pen for about five months of the year in 2018-2021, and from general pen operations, the natural vegetation within the pen has been degraded. Lichen in the pen has been significantly reduced due to heavy foraging, and shrubs such as willow and scrub birch have been browsed to the point where many have died or become stunted. Since Mt. Rochfort lies within critical winter and calving range for the Klinse-Za herd, the restoration of this site to expedite the return of valuable forage is important. Restoration activities included planting scrub birch seedlings, translocating reindeer lichen (Cladonia sp.), per- forming a small willow cutting trial, and obstructing a trail leading to the alpine. This year, on June 23rd, a crew went back up to assess the effectiveness of this restoration work.

We planted scrub birch seedlings in three main areas within the pen; the alpine, subalpine, and large wet meadow. In the alpine and subalpine areas we did not see a single planted seedling, so we thought perhaps they all died. Upon further observation, we found that the holes where they had been planted slightly opened up, and some perfectly intact plugs were seen laying nearby (Figure 8). Very few were left undisturbed. And we had to conclude that an animal

must have dug them up; this leaves a lot of potential suspects – was it a Marmot? Bird? Porcupine? Deer? Squirrel? All are found in the pen area. Whoever it was, luckily it did not seem to like the wet meadow as much, since those seedlings seemed to be primarily undisturbed and healthy (Figure 9).

The reindeer lichen translocations were quite successful. Considering there were no mats and very few fragments in the alpine last year, anything found had to be from the translocations. We quickly noticed some large mats in the alpine area, and most of the lichen seemed to have stayed in the place where it was planted and had attached itself to the surrounding vegetation or ground cover. This lichen can now act as a source for further reindeer lichen to establish in the alpine.

For the willow cutting trial, two species of willow were staked on site directly into the ground. There were ten stakes of each species. One species had a 50% survival rate, with low health and vigour scores and no leaves, just a couple of primary roots. The other species had a 90% survival rate, with most stakes scoring high on the health and vigour scale and lots of primary and secondary roots, as well as some leaves and shoots. This trial did surprisingly well despite the cuttings being harvested outside of their dormancy period last summer and the harsh, high- elevation environment that they were planted in.

We used on-site coarse woody debris (downed trees and logs) to discourage the use of a trail leading from the cabin to the alpine, by laying them across the trail and thus obstructing movement. The shade and moisture from the debris helps facilitate the return of natural vegetation along this feature and discourages predators from using it as a linear corridor to hunt caribou. We also added a sign this year to discourage people from using motorized vehicles on the trail. During our check, the piles of debris were still present and upon reviewing the photos from a trail camera set up along the trail we noted only one predator using this trail once, a grizzly. Also, a few sows and cubs were seen at the cabin area throughout the year but they did not go up the trail. There was no sign of motorized vehicle use of the trail.

In addition to our efforts, the Rochfort pen site is slowly recovering on its own, with more vegetation coming back every year, though it will take a while for the area to return to pre-disturbance conditions. Since only limited information is available with regards to restoration in high alpine areas due to its harsh climate and short growing season, this project may help address current knowledge gaps in alpine restoration as well as lichen translocation.