This is the magic time of year when people start to look for and see young moose. The calves are being born and begin their amazing growth that will prepare them for winter. WTIPs Jay Andersen talks with a local naturalist about moose.
Chel Anderson is a botanist and plant ecologist for the Minnesota Department of Natural Resources. She lives here in Cook County and joins us here periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.
Anderson: Hi, Jay.
Now, everyone’s favorite large mammal, moose, when do we start seeing moose calves, or are the around already?
Anderson: Well, I haven’t seen one myself, and I haven’t heard that someone has, but that could well be, but typically in Minnesota moose calves are born starting in the second week of May and going thought the end of May, the fourth week in May, and pretty much all the calves are born during that bit of time. If the cows have been in good nutritional condition when they go into the winter and get through the winter well, then they might be having one or even two calves. Twin calves, historically, have been very common in our northeastern Minnesota moose population. Unfortunately, that’s been declining, but we can still hope to see twin calves out there occasionally. One question I’ve had about this is why would they all be born in this tight little timeframe, why not a little bit earlier or a little bit later? They seem to really be concentrated. No one really knows all the evolutionary factors that have led to this, but one of the kind of leading theories about this is that it has to do with something called “predator saturation.” So, if you are an animal who’s young is very susceptible and vulnerable to mortality from predators when they’re young, very young, then it can be beneficial for all of you to have your young at the same time, because then you give the predators all these choices. So, individually or each calf, or each cow’s calves, have a better, higher probability of being overlooked by a predator, because there’s so many other choices out there. So, that’s one possible reason. But, in any case, it gives us a great opportunity to see them, because they’re all being born pretty much at the same time. Pressure from predators is another very significant factor in where calves are born. So, cows are careful about where they choose to give birth to their calves. They want some place with dense cover, not just tree cover, but shrubs. That helps make it difficult for the calves to be seen and the cows to be seen when they are lying down close to the calves. It also helps to be somehow isolated from easy access by land. So, islands have been documented to be very often chosen as moose calving sites as well as even peninsulas, because it just narrows down the directions from which predators either intentionally or accidentally stumble upon the cow and calf or the calf if it’s alone. So, both islands and peninsulas are important places, and it’s also useful if there’s good brows for the cows, so she doesn’t have to go that far to feed when she needs to in between before the calf can really be moving around very far. Calves, when they’re born, are between 25 and 30 pounds. So, big relief to the cow. But then, of course, another sort of chore is to take over, and the calves are pretty helpless, you know, when they’re first born, but they can walk or stand and walk within a day or two, and then start gradually moving around as directed by their mother. The moose calves are the fastest growing mammal on the North American continent. Well, and they need to, right, because they have to make it through a winter in just several months. Initially, they’re feeding strictly on the mother’s milk; that lasts for a month. When they’re feeding on the milk, they’re growing two to three pounds per day. So, when they’re doing strictly dependent on the mother’s milk and when they’re really young, they can’t go so far, right, and they don’t have the strength and agility to manage some of our cross-country travel. So, the cow is assessing all that as her calf or calves develop and, you know, just making the choices about well, we need to do this or not do that, and go here, go there. But, the cow has to take care of herself as well. She needs to find what she needs, but as she recognizes her offspring have the strength and capacity to move, she’ll keep pushing them to do a little bit more and get a little bit stronger. Calves are often swimming by a week old. It’s really remarkable how quickly wild creatures have to become adept.
Chel Anderson, DNR botanist and plant ecologist, thanks for helping us understand what’s going on around this spring.
Anderson: You’re very welcome.