For those that have extensive first-hand field knowledge/experience on beaver population dynamics:

When beaver reach the age when they leave the colony where they were born, do you see more lone females (than lone males) setting up in new areas, ie building dens/lodges and conducting water control by herself? Often times these "new" locations are a long way (miles) from any other beaver.

I've noticed that at several new beaver nuisance locations that I'm encountering a female and no male. Landowners say beaver(s) only been there about a year. I trap that female and there are no other beaver there. Dam breach = water drains out. No sign of another beaver.

Of late, single beaver situations like this are nearly always a female. Some I caught have had kits (they have 1 to 3 dry udders), but most have not.

What am I observing here. Primary female dispersal? Is she the one that leaves the colony and a male eventually finds her?

Just curious...because this is definitely noticeable.

One thought that comes to mind if your seeing it this time of year, is the male went on a walk or swim about for breeding season. May have got in a fight with another beaver and got killed, hit on a road, or found by another predator. Maybe the bred female needed a place to call home.


My experience in MN…
Almost no suitable areas here that haven’t been occupied recently by beavers….so it may be a different scenario. And we don’t have open water for breeding season, so that is another variable I do not know.

Almost all new colonies are a pair of beaver.
Many places that have been trapped, the adult female is the hardest to trap, and often left behind by the initial trappers. Places where an adult female is left always has a new male move in the following year.
Areas that have been active for years and have been trapped and only have a single beaver that hasn’t attracted a mate is often a male. Kill that lone male and a new pair will move in.

3 years ago something in the southern beaver world changed and i don't have a clue what it was. They act as goofy now in Jan. as they do in June! So who know's with your's, maybe they are living 'alternative' lifestyles.

I have wondered why the adult female is often the last one that is caught. I do not know why.

Rickey

My experience mimics Mike's. (in MN).

I find an adult pair at many locations too amd you may be correct about the missing male. But, it sure seems to be happening in a lot of these areas here.

How and when did that pair of new beavers get there? Female get there 1st by selecting that area and set up house and a male found her? Or did the male arrive and 1st (choosing that location) and along comes a female? Or did they travel together once they met up and set up shop together.

During the 30 years of full time beaver trapping in NC, I've only encountered sites with a single female less than 10 times. I usually encountered two year old pairs more than anything else. This was after I cleaned out the original colonies. Sounds like you've got a strange phenomenon there Mr. Dupree.

It is strange for sure Paul. Because I'm trapping so many different locations at once across a 50 to 60 mile radius I've noticed this.

I've already seen more than 10 instances of this in past several months. Granted some of the locations may be a deceased male and others I may be missing the male that has just spooked away from the control area.

I had a call last summer that beaver were plugging a culvert. The first year I trapped it I took a pair and four kits. I had trapped the same place three or four years in a row with just a pair of two year old's, one male one female after that. I go in and set a choke spot and have a two year old male the next day. Reset it and no sign for a week and looked area over pretty well. I tell the land owner to call if he sees anything. He calls about two and a half months later and says a beaver is plugging the culvert again. I go set it up and have a male two year old the next morning then no sign again. The land owner says Yea I knew there was a pair. I never did tell him they were both males.

Pretty much the same here as far as beaver pairs setting up shop. One exception is that fairly often I will see entire colonies make a move in the spring. River beaver will leapfrog up or downstream to better food sources (usually less than a 1/4 mile), Pond beavers will move to adjacent ponds. If we have a very dry summer, colonies will move surprising distances to find water before freeze up.

I've always read and heard the typical beaver dispersal theories....2 year olds leave the colony...new pair moves in to depleted colony or new area....beaver disperse in fall....etc.

But, there are some gaps in some of this "common" beaver knowledge based on things I see.

I see dispersal during high water events....no matter the season. Ease of travel likely enables this. Other times of year...no dispersal...they'll live tight with one another....

Water availability controls the show.

Have caught up to 3 nursing females in same headwaters pond of only 4 or 5 acres in a few days time.

This lone adult female beaver thing has me puzzled.

I still like to catch the brood female 1st or quickly. But, here lately, not sure if there's only 1 or several breeding females there.

After a hurricane, I had beavers in places they have never been. They definitely move when flooded, and also move during droughts.

I have also caught as many as four lactating female beavers in the same colony. I've also caught as many as 9 adult male beavers plus 8 adult female beavers from one site, and they were all adults and not bit up. There were some strange anomalies I encountered during my beaver'n career.

Recently, I caught 2 very large males from the same lodge. Very unusual. When skinning I found the one male had damaged genitalia. I think he was just treated as a neutral member of the colony. More common to find multiple breeding age females.

I don't know much but what I do know is there is no set rules.

Trapping though the ice, on many occasions I will catch multiple adult beaver around the same feed bed.

Once location that comes to mind this winter was a pond that was less than 5 acres, I caught three beaver that were over 50 lbs and 5 yoy.

Another location that I am still trapping that is on a somewhat large lake there are 5 colonies, one colony I have caught 4 adult beaver, another 2 adult beaver, another 3 adult beaver, 4 adults and 2 2 year olds at number four and at the final colony one adult.

The most I can think of out of one colony is 6 adults.

I don't keep track of sex so I can not say if they are male or female.

If you talk to a field biologist they generally stick to the simple rule of thumb (adults, 2 year-olds, and pups). Trappers dig a little deeper and find out that it's more complex than biology 101. Lots of variables.

I see a good mix of single females and males. The majority of new arrivals are pairs, with maybe 3 or 4 pairs for every single that moves in. But that single can be either male or female. Although I would have to really crunch records’ numbers to figure it out, it seems like I see more single males than females. I did have 4 big females over 45 pounds at one location within a week this past fall, only one had teats from young the past summer.
I’ve been saying for several years that one of the unique challenges to doing beaver nuisance work is that compared to other animals, there is quite a bit of behavioral variation with individual beavers. There are most definitely general “standards” of behavior, but about one in 5 or 10 individuals acts very different for whatever reason. At least that’s how it seems around here. As a fur trapper, I never even knew because those were just left while I looked for fresh colonies. Now that I have to get those individuals I have realized it.


That is a very good thing to remember. I deal with elm trees a lot, and if you ask a forester or botanist they say there are three species of elms around here. But to me there are 6, because there are 6 distinct types of bark on those three species and each has unique characteristics and works differently. Anytime you are working with a natural resource daily, you start to see local trends and differences from the norms or generally accepted “truths”.

Perhaps you weren’t the first call. Summoned To clean up the scraps.

Seen same thing as you and Paul, took 6 prego females out of one pond , took 7 out of another spot years later. The 6 i skinned and put up, like paul said, no bite marks nothing. When asked how many ya think are in there from land owners my answer is always somewhere between 2 and 20, lol. Just took 12 out of a mudhole id not think had 2 in it and bad thing is im not done yet.

But your single white female deal, ive not ran into that. I have ran into a big whale of a old female and catch one little dinky male i thought was her offspring several times and that be it. Reality is the little male was probably her mate.

In the south about EVERYTHING the biologist wrote about beaver's isn't correct, they pretty much do what they want to down here when ever they decide to do it. No rhyme or reason to most of it.

Yep this is a lot of what I see also. But have found in the last couple of falls that when a pond dries up I end up getting possibly 2 pair of beaver in a pond. 2 lodges also. So I wonder if in the fall if the original male doesn't do any chasing that time of the year. This past fall in one experience was 2 lodges a short distance apart. I set and caught 2 big males and 1 big female. That seemed to be all that was there. I think the reason the female is the last to catch because she don't travel to far from the lodge especially in the spring. If I catch her it usually means I am done.

Maybe a feminist beaver has influenced the tribe and you have a bunch of independent self sufficient beaver?
In all seriousness I'm no expert on beaver.
But when we would have a red fox explosion after a crash the littler sizes would increase and the female To males ratio would increase. The opposite would happen when the population was waning.
In the high population sometimes a den may have 2 adult nursing females and one dog.
Many times a yearling dry female also..
Could it be posable you have an unusual high population of the woman's with fewer men to Bread .
And nature causing a low birth rate to reduce populations. .
It would be interesting to know if the kit #s are more boys.
Rich