On the most recent Porcupine Caribou herd satellite collars. A lot of the herd is bunched up against the Dalton Highway. They always go that far but never seem to cross it. As they have no problem crossing the Dempster Highway from Dawson City to the NWT border I was wondering why the don't cross the Dalton Highway. Is it different country on the west side of the Dalton Highway? More hunters / predators? I cant imagine it is much busier than the Dempster Highway.

Pipeline?
If they are that far west they are mixing with the central arctic herd.

Chemicals on the highway?

Or, maybe they get too far from the smell of maple if they cross.

The Porcky herd has never been higher. I think they are taking over the Central Arctic herd. They have been going to the Dalton regularly for several years now. Check out the PCMB web site.

Seriously you guys I really want actual opinions as to why you guys think they do not cross. They cross the Demeter readily so I don't think it's the dust suppressor.

I have not been up that way since 2018, but use to hit every year prior to that. What I noticed was the travel ways changed alot when the were doing the under ground testing looking for oil reserves. Between that and helicopters there was alot of traffic. The terrain aint much different on the west side were the artic herd normally comes from in August. Doubt it is hunting pressure. It has always been weird to me how animals set boundaries' or territories, but it always involves food. So maybe what they chow on there aint as much on the west side.

Yes HFT that is very possible. They may be crossing but the map is too large and missing it. But it is probably territory and feed. Whatever it is they are eating there must be a lot of it this year as there are a ton of them right up against the highway. Anybody know how the snow condition along the Dalton?

I fly into Coldfoot and Bettles fairly often, and have seen some lately southeast of Bettles, in the Kanuti Flats, and some southwest of Coldfoot near the confluence of North Fork and Middle Fork Koyukuk River. So a few are crossing the road. Lots more south and south east of Coldfoot. Very interesting movement this year. Has the herd grown significantly lately?

Yes the herd is at record numbers right now. The herd information and is available on the PCMB web site https://pcmb.ca/satellite-collars/. Ill go on Google Earth and see where them places you mentioned are. Im hoping to make a trip to Barrow if COVID ever ends see some of that country. Also my wife's family may have left a kennel of malamutes there before they left for Canada in the forties. They said they are still there want to try get a pup.

The graph on the website puts the Porcupine Caribou herd at around 250000 caribou.

Thanks for the info 30/06

We have a similar issue on our DMTS highway (the Red Dog road). It's a 52 mile road that goes from the mine in the mountains to the port at the ocean. It's basically an East to West road. The Western Arctic Caribou herd travels from north to south in the fall, and reverse in the spring. Years ago, our main caribou biologist saw on the collar data that there was a lot of "bouncing" off the road in the fall. Caribou would approach the road at 11 miles an hour and hit it and go back north the same speed most of the time. They would try again and again. Some would bounce 6 times before crossing. Some would just go way back up north and winter there after their first bounce, and die on the north side. Others, after bouncing a few times would go east and around the road. Nobody at the time knew the reason for this bouncing. Could it be wolves? Bears? Trucks/vehicles? Local hunters on four-wheelers (shareholders are allowed to hunt on the road in the fall). Nobody knew the answer to this question. By policy, trucks are only allowed to stop if the caribou are within 100 yards of the road. Not sure if that changed, but there was talk about that, as these trucks are very heavy and going decent speeds. Not sure about the policing of these policies either. Also, there were some young hunters on four-wheelers who were not letting the lead herd cross the road. Our biologist wanted at least 10,000 to cross before hunting begins, but due to political pressures, they open it after a few hundred cross.

I personally observed the first herd in the fall approach the road. The trucks were ordered to stop, park and leave their vehicle and get a ride back to the mine or port, whichever way they were traveling. At the same time, hunters were not allowed on. A herd of about 400 approached the road, didn't cross it. Just ate, laid down, mingled, the whole day and night. As if it were some "rest stop" to just chill for a little while. The next morning, they ate some more, and that afternoon, crossed as if the road were not even there.

When I asked the biologist about this, he noted that caribou have a strange sense to stop and wait at certain places for the rest of their buddies from time to time. And no matter how far they are apart, some could be 100 miles south, somehow, they all know to stop at the same time! Not only that, but if they reverse their trek, whether they are 100 miles south or not, they ALL reverse their trek, as if they are communicating with one another. The biologist retired not long after these discoveries, so there are no real answers to these questions. It would be nice to get some Laplander reindeer herders, or some from Eastern Russia herders to come and check out what/why. My theory is weather. That's the only logical explanation as to their synchronized movements 100 miles or more from each other. A warm weather system will push them all back north, while a cold system will help bring them all down.

One other thing that the biologist noticed is that let's say caribou bounce several times off the road and then cross, they actually speed up quite a bit after crossing so as to "get back on schedule". Also, what caribou do here is once they cross the road, they'll go this fast to "the next checkpoint, or rest place" and wait for their buddies to catch up. Once their buddies are caught up, they'll go fast again to get back on schedule. Last, the caribou not only bounce going south, but let's say some cross the road north to south, and a warm front comes, they trek back north, well, for some reason they bounce again! Sometimes 3-6 times going north in the fall! So there is something about a road, because hunters are not on it and trucking really slows down in October/November. Crazy.

Our herd is climbing back slowly. I think we're around 230k. Used to be 480k. My personal opinion is climate change has had a lot to do with the decline. They also come through the Kobuk River and Noatak a LOT later now. I haven't shot a fall bull in September in about 10 years now. Kotzebue should see our first caribou any day. One day there'll be nothing on the ocean ice (the coastal group coming from that road) and the next they'll be shortcutting through our ocean ice to "catch up, get back on schedule" and flow right around town. The problem with such a late migration is we harvest a lot of females, as bulls are in rut. Also, because Kotzebue area is not a rest stop area, it's a "gotta catch up and get back on schedule" area, they move through pretty fast. So gotta get what ya can when they're here.

Muskrat, I would have a good biologist look hard at that collar data and even get some observers on the road where they're congregating/bouncing. See what the cause is. It may just be that they made that a resting place before their next big push to the next resting place. idk. Hope this helps.

Interesting! I have seen that same behavior when they are wanting to cross the river with ice running.

They will try it but then turn back and camp on the bar for a couple days. Then they try again but repeat the process. Eventually it's like a light comes on and they realize that if they don't go NOW they will have to wait until the ice is solid enough to support them. At that point some old cow will plunge in and they all go for it.

I can see climate change altering the dates that the herd moves. That makes sense to me. But I can't imagine that it would have any bearing on crossing a road or not.

That road must look like a hundred other clear gravel places they encounter. I would be willing to guess that it's more odor from diesel or rubber that makes them pause. Maybe it is vibration in the ground from trucks that they can't see ?? They aren't the brightest critter under the sun either.

There is a group of Natives in NE Alaska that are adamantly against oil drilling in ANWR. Saying the porky herd is at an all time high isn’t helping their cause, Muskrat!!!🤫

It public knowledge. Any one could look it up on the website I posted

Do you think . successful Caribou populations and development on the North Slope are mutually exclusive?

There is not a caribou on the North Slope that was alive in a time when there was no Dalton Hwy and no pipeline!

It's not "unnatural" to them. It has always been there and a part of the landscape.

W17's theory on the smell of rubber and diesel fumes makes the most sense to me.

Pete

I also like the theory that the highway was just put at the natural extent of the Porcys western range. And it's also clear that they do cross the road.
Trapperman is the best you ask a question and actually get answers that help. I have a better understanding now.

The caribou won’t cross because they don’t want people making jokes. A chicken crossed the road one time and we all know how that turned out.

There ya go...... simple explanation!

Pete

Why did the Turkey cross the road? Chicken's day off.

Boy.... you can always tell when there isn't enough snow for trappers to get out and do some legitimate work....!

Pete