Today's News
A/CPB
Caribou Migration Update: April 3, 1997
| To: | Journey North |
| From: | Robert Mulders, NWT Department of Renewable Resources |
| Date: | April 2, 1997 |
Robert Mulders
"Our helicopter arrived on Friday evening (March 21) and we headed out to the Sealhole cabin on Saturday morning. Using radio tracking gear, we were able to pinpoint our collared females from the observed groups of several thousand caribou. Dave did the shooting with the net gun on this trip. Once the net and collar were removed, the caribou were set free.
Robert Mulders
"As you can see from the following data, we were successful in retrieving collars #6978, #6980, and #3925. There are still 3 collared caribou which we will continue to track.
#6977, #3924, and # 3926. It appears that #3924 has been heading north and is joining the Beverly herd. Since #6977 & #3926 have recently been swinging eastward, it's still unclear which herd they will link up with, Beverly or "Qamamirjuag"(Kaminuriak).
- Link to Today's Data
"We noticed that there was less snow than normal out on the barrens and along the tree line. Many of the eskers and small hill tops had relatively little snow, providing caribou with easier access to their food supply. This likely explains why the caribou appear to be in good condition this spring.
Robert Mulders
"Wolf packs are commonly found associated with larger caribou concentrations at this time of year. Along one of the caribou trails we found the remains of a caribou (head, vertebrae, and a few tufts of hide); an obvious wolf kill. We spotted one wolf which was light grey in colour.
"Unfortunately, we did not have the helicopter time (i.e. budget) to do much classification of caribou from the air. Later this month, Dave and a local Inuit hunter will travel out by snowmachine and observe these migrating caribou with a spotting scope. Caribou will be classified into sex and age (calf, yearling, and adult) categories in order to determine what portion of last June's calf cohort has survived the winter."
Cheers,
Robert Mulders
In our last update, Mulders shared the results of his Spring, 1996 composition survey. He looked at the calf:cow ratio (the number of calves per 100 cows) during the spring migration. Out of 13,488 caribou, on average there were 42 calves per 100 cows. However, according to these data, he noticed the ratio changed as he went further north:
| Latitude | Calf:Cow Ratio |
| North of 60.40 N | 26:100 |
| 60.20 N-60.40 N | 37:100 |
| 59.45 N-60.20 N | 82:100 |
Mulders said this pattern was significant, but we didn't tell you why. Instead, Challenge Question # 6 asked: "Why do you think there were more calves per cow in the south than in the north? What do you think this patterns confirms?"
Here are answers from students, followed by Robert Mulder's interpretation:
From VERMONT:
"We think that there are more calves per cow in the south as it is warmer
in the south and more food is available. In the north, because it is
cold the mothers might die while they are pregnant or lose their calves."
David E and Zachery C. Grade 6
Ferrisburgh Central School, Ferrisburgh, VT
lthurfer@pop.k12.vt.us
From ONTARIO:
"The cows in the south have more calves because there is more food in the
south than the north."
Cory Wouters,Gehan Nemat
Cleardale P.S.
WOUTERSC@cleardale.lbe.edu.on.ca
Robert Mulders interprets the data this way: "As the migration progresses, cows are leaving their 10 month old calves behind, hence the high proportion of calves to the south." Right now this is probably occurring again. During April and May, as caribou mothers migrate to the calving grounds, they leave last year's calf on its own for the first time, and turn their attention toward this year's new offspring.
The Next Caribou Migration Update Will be Posted on April 17, 1997.