Thoughts on how an ice bridge works

[Spartan]

With the polar vortex in full effect this week, I started thinking about the possibility of an ice bridge forming this winter. That got me thinking about how this actually works for wolves and other animals to cross over to the island.

I imagine that ice bridges form gradually, from the shoreline out to the middle of the lake. So it takes several weeks of cold weather and water freezing for the two to eventually meet. And then it might last for a short period (a few days/weeks?) before temperatures warm up and it's gone.

So how do the wolves know when the ice bridge is completely formed? Do they wander out to the middle of the lake, five or six miles, only to find out that they can't go any further and then turn around and head back to land? And then try again the next day, and the next day? Or are there multiple wolves randomly wandering around on the frozen lake, and by chance a few are actually out there when it's completely frozen and make it across? I wonder how "intentional" they are in doing this, or if it is just a matter of timing. It's not like it is a small pond that they can look out across and know that it's frozen all the way across -- it's 16 miles, right? It's kind of a long distance to walk not knowing if they can make it the whole way.

This has always intrigued me, so if anyone can explain it, I'd love to be enlightened.

[treeplanter]

Maximum ice formation on Lake Superior is usually the first week of March. As for why wolves would make the trek across the lake to Isle Royale, I was told once by a biologist that one reason animals leave their traditional territory is in search of food. As for how the wolves do it, test the ice, etc., I don't have a clue. But they do travel across the ice, that we know. One female left the island three or four years ago, and a pair of wolves came over the following year only to go back to Ontario. I'll be curious to see what happens this year, if an ice bridge forms, and if the new arrivals make a beeline back to Minnesota.

[Spartan]

As for why wolves would make the trek across the lake to Isle Royale, I was told once by a biologist that one reason animals leave their traditional territory is in search of food. As for how the wolves do it, test the ice, etc., I don't have a clue. But they do travel across the ice, that we know.

I get why they do it, and of course we know they do. But my question is how they even know that the ice bridge is there. It seems it would just be a matter of chance that a wolf would walk in that direction during the time that the lake was completely frozen. I wonder how often a wolf walks out for several miles, gets to water, and thinks "dang, guess I'll turn around and head back..." I would imagine a wolf might try that once, figure out it's a lost cause, and then never again.

[treeplanter]

They probably do as you suggest. They see that big blob of land on the horizon, are intrigued, and start off across the ice. How far they go depends on ice conditions.

I imagine it's easier for a wolf to walk on ice than in the bush, so that may be one reason why they're on Lake Superior in the first place. Pack pressure and food are probably why they look at Isle Royale as a place to go. I've personally have seen wolf tracks on the Straits of Mackinac between Michigan's Upper and Lower peninsulas. Some have crossed over to the NLP, but not many. Maybe wolves are also explorers at heart.

[Midwest Ed]

You can read here in this National Geographic article some thoughts of Rolf Peterson on the subject. It covered the time of the tracking of the Minnesota pair that crossed over, spent a few days, then returned home.

I think it's about food, procreation and socialization. What else is there? I just recently ran across a discussion in another forum about how easily a pack very near Anchorage Alaska changed their diet and eating habits after they discovered how they could much more easily kill local pet dogs than moose. This happened 8 to 10 years ago. There was one report where a group of 3 wolves surrounded a couple of women jogging with the dogs, only to lose one dog to the wolves. Apparently, it required trapping some of the dominant pack members to stop the aggression.

[Spartan]

You can read here in this National Geographic article some thoughts of Rolf Peterson on the subject. It covered the time of the tracking of the Minnesota pair that crossed over, spent a few days, then returned home.

Interesting article -- thanks. I hadn't read that one before.

There was one report where a group of 3 wolves surrounded a couple of women jogging with the dogs, only to lose one dog to the wolves.

Wow! I can't imagine how gruesome that must have been to sacrifice one of your dogs to save the others (and maybe yourself!).