Here's the latest, and also the last update for this season, from our caribou cows in NWT, Canada! We hope that you have enjoyed tracking the caribou on their journey north, and learning about the amazing caribou and the important role that caribou play in the cultures of many native peoples. We want to send a special "thank you" to our experts Robert Mulders and Dave Abernethy of Renewable Resources for sharing their data and expertise throughout the season.
Our experts have sent in the latest caribou data, and Robert has also answered several interesting questions about the caribou. Both the data and his answers are typed below, and we think you'find this information helpful in interpreting some of the latest movements of the caribou.
Here are today's new locations:
Caribou #06978
May 21: 62.987 N, 93.738 W
May 26: 63.013 N, 94.301 W
Caribou #06980
May 21: 62.404 N, 93.784 W
May 26: 62.404 N, 93.784 W
Caribou #23924
May 21: 65.292 N, 100.657 W
May 26: 65.428 N, 100.602 W
Caribou #23925
May 21: 62.852 N, 93.616 W
May 26: 62.915 N, 94.388 W
Caribou #23926
May 21: 62.882 N, 93.752 W
May 26: 62.877 N, 94.324 W
The following information and comments were also sent in by Robert Mulders. His data about the numbers of calves per 100 caribou is very interesting.
"Here briefly is a summary of April's spring composition survey on the Qamanirjuaq herd, as well as a response to your recent questions.
I classified a total of 13,488 caribou and found that overall there were 42 calves per 100 cows. It was interesting that in the northern portion of the migration (north of latitude 60 40) there were 26 calves: 100 cows. In the central portion of my sample (between 60 20 and 60 40 latitude) there were 37 calves: 100 cows, and to the south (between 59 45 and 60 40 latitude) about 82 calves: 100 cows. This pattern confirms that as the migration progresses, cows are leaving their 10 month old calves behind, hence the high proportion of calves to the south. This calf survival rate is slightly lower than, but in line with, recent spring surveys:
1993.....46:100
1994.....48:100
1995.....47:100
1996.....42:100
Since this is the final caribou update, we thought we would take our turn and "Ask The Expert" a few questions to wrap up our journey with Robert Mulders, David Abernethy and, of course, the caribou. Here are Robert Mulders' answers to our questions.
To: Journey North
From: Robert Mulders,
Regional Biologist
Q: Has the "Ice-Out" occurred yet on the lakes in the calving grounds? On the rivers?
A: Many of the large lakes (i.e. Beverly Lake, Kaminuriak, and Banks Lake) are still largely covered with ice several feet thick. This ice won't be entirely gone until early July. Some rivers are already flowing, and many of the smaller lakes are only now starting to melt along the shorelines.
Q. Are there difficult water crossings we could point out to where either of the herds must cross?
A. There are numerous water crossings throughout the region, although some are only occasionally used. Some more commonly used water crossing are located at:
Heniks Lake Narrows:........61 44 X 97 30
Northwest Kinga Lake:.......61 54 X 96 48
Maguse River:.................61 56 X 96 29
Christopher-Bowel Islands:..64 07 X 94 34
Thelon River:...................64 47 X 96 56
East Schultz Lake:.............64 40 X 97 10
East Aberdeen Lake:............64 37 X 98 25
East Central Aberdeen Lake:..64 34 X 98 33
Dubwant River:.................64 24 X 99 53
East Thelon Sanctuary:.........64 33 X 101 10
Although caribou are excellent swimmers, they can get into trouble. If caribou travel over thin ice, they occasionally break through and either break limbs or become stranded and die. Drifting ice and strong currents also pose hazards. During the summer months caribou may become weak ( due to insect harassment) and succumb at wider water crossings.
Q. Please describe the calving grounds. How concentrated are the cows? If you fly over, what does it look like?
A. The Qamanirjuaq Caribou Calving Ground has historically centered about 150 km south of the community of Baker Lake. The tundra surface is scattered with rocky outcrops and has an average elevation of 100m asl. Vegetation types include: rock barrens, lichen, steppe,lichen-heath tundra, dwarf scrub-lichen tundra, tussock tundra, sedge meadow and transition forest. The calving ground is dotted with numerous lakes and ponds, most of which drain in a southeasterly direction into Hudson Bay.
The size of this calving ground averages about 33,400 km2, and caribou density can be quite variable from year to year. As well, densities on the calving grounds can vary considerably. It can range anywhere from 5 caribou/km2 to in excess of 400/km2. After the peak in calving, cows can concentrate into very dense groups of many thousands of caribou. From an altitude of 2,000 ft. the caribou look like grains of rice scattered over a vast area.
Q. Is the 1987 post-calving survey of 260,000 animals a good estimate of present numbers.
A. Our calving ground surveys are only designed to estimate the number of breeding females in the population. Our intent is to monitor the trend in the number of breeding cows in the herd. We then also extrapolate the proportion of yearlings, non-breeding cows, and bulls in the population, to arrive at an overall population estimate. In 1994 our estimate of total population size for the Qamanirjuaq herd was 496,000, which is considerably higher than the 1987 estimate.
Q. What is the area of each herd's calving ground, roughly?
A. Over the years the Beverly calving ground has averaged 14,700 km2 Over the years the Qamanirjuaq calving ground has averaged 33,400 km2
Q. Do you think #06978,#06980,#23925, & #23926 have arrived yet?
A. These caribou are getting fairly close to where they will calve. The caribou with collar 6980 appears to be further south than the others, but should catch up shortly. I suspect that the calving grounds will center roughly around 63 00 X 94 00. As of May 26, these collared caribou were located at:
6978.....63 01 X 94 18
6980.....62 24 X 93 47
23925....62 55 X 94 23
23926....62 53 X 94 19
Q. When do you think calving will occur?
A. A few calves may already be born, but the peak of calving (when 50 % of the calves have been dropped) will likely occur sometime between June 3-8 for the Qamanirjuaq herd. The peak of calving for the Beverly herd is generally a few days later and may peak around June 6-11.(Editor's note: It is interesting how the calving seems to be synchronized among the cows in a herd)
Q. How do you know?
A. Just prior to calving the cows will stop moving-which will be reflected by the limited movement on our collars. A day or two after calving the cows should start moving again. During the second week of June the duty cycle on our collars will convert to daily transmissions for 14 days which will provide a detailed record of how cows move off the calving grounds. These dates may vary a little from year to year but seem to hold up whenever we are actually on the calving grounds and can visually confirm the timing. During our census work in the 1980's and as recently as 1994, for example, the above dates fairly well represented the peak of calving. This year, we won't actually be conducting any work on the calving grounds and, therefore, can't verify the timing.
Q. Is Caribou #23924 part of the Beverly Herd?
A: This cow was collared in early April 1995 to the NE of Neultin Lake (around 60 45 X 98 30) and was travelling eastward within a large movement of "Qamamirjuag" caribou. We considered this area to be Qamanirjuag winter range, and were quite surprised when several days later this collared individual promptly swung around to the NW and passed Dubawnt Lake on its way to the Beverly calving grounds. This cow over-wintered further west in "typical" Beverly range, and is again using the Beverely calving grounds. It's hard to say whether this was a Qamanirjuag caribou which switched herds, or whether this is a Beverly caribou which just happened to briefly get caught up with the wrong crowd last year. This issue of herd intermixing and female fidelity to calving grounds is an important management question. Telemetry studies on Qamanirjuag caribou in the mid 1980's suggested that about 3% of cows were not faithful to their previous calving grounds.
Q. Do you think she's arrived on the calving grounds? Given birth yet?
A. This cow was at 65 26 X 100 36 (43km NW of Sand Lake) on May 26 and had travelled about 8km in the previous 5 day period. Although its possible she's already given birth, it's probably still a bit early. I suspect this cow is almost on the calving grounds and that the majority of the Beverly calves will be dropped sometime between June 8-11.
Q. How large is the Beverly herd? (Area and population size.)
A. The Beverly herd utilizes a large portion of the central barrens over the course of a year, and typically its calving grounds occupies an area of about 14,700 km2. Based on the last calving ground census for the Beverly in 1994, we came up with an overall estimate of 286,000 caribou for this herd.
Q. Please describe the warble and nose bot flies.
A. As parasites, the warble fly (Oedamagena tarandi) and nose bot (Cephenomyia trompe) tend to cause a general debilitation of caribou. The warble fly appears to be by far the most prevalent. Kelsall (1968) offers the following description:
"Warble flies are bee-like in appearance and colouration, and are on the wing from late June to September. Eggs are laid on the caribou under hair often along the legs. Larvae hatch in about a week, penetrate through the skin, and migrate to the back where they cut breathing holes. Larval development continues throughout autumn and winter in a fibrous sac. In late May and during June the larvae leave the caribou through the breathing holes and pupate on the ground. Pupation takes about 2 days and the pupal period lasts about a month. Every caribou hide I've ever examined has had anywhere from 20-350 warbles along its back."
"The nose bot (or nostril fly) has a similar cycle. It is also bee-like in appearance but dark, almost black. The female adult fly deposits larvae in the nostrils of the caribou, and the larvae work their way back to a point in front of the entrance to the throat. Larval development is slow until March, when it speeds up until full growth is attained in May. The larvae drop to the ground and pupate within 6 hours, and the pupal periods last from 2 weeks to a month."
Cheers.
Robert Mulders
Regional Biologist
c/o Rankin Inlet
(Thanks to the Government of the Northwest Territories for providing some of the pictures for today's report from their book "People & Caribou In The Northwest Territories". Also, special thanks to Robert Mulders for sharing his pictures.)
This is the FINAL Caribou Migration Update.
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