So just to be sure I understand what you're saying;

The YOY will show 3-10mm of closure to go before the bone is no longer visible. In other words, still shows 3-10mm of bone whereas the adult will show 3mm or less visible bone.

Gulo


You have my attention. I have been around a fair bit of this type work while working part time at the Montana Fish and Game Lab in Bozeman while attending college. It was here that looking at uterine horns etc was introduced to me and I have used it a lot in my classrooms as a teacher and with my kids. I found it to be fascinating It is really fun to show people how many young an animal has had the previous year etc in such animals as mentioned.
As you mentioned, and for the readers here. Fand G would look at scars in the ovary for the number of eggs that were released by a female. And compare this with the number of scars left on the uterine horns. The number of young that had implanted on the uterine horns and thus given birth to.
Some good info here
http://en.wikipedia.org/wiki/Corpus_luteum

(corpus al·bi·cans (lb-knz)
n.
The white fibrous scar tissue in an ovary that results after the involution and regression of the corpus luteum.

How realistic is this for the untrained eye. I would like to try this. Just looking I could not find anything. Maybe a microscope would be what is needed. Also on a first year breeder. Bred in say July on her first cycle. How would the uterine horns look in Dec/Jan as compared with a YOY and Adult breeder in terms of development of the uterine horns. Guess what I am looking for is could you say that she is a first time breeder due to the lack of development compared to a previous breeder yet substantially more developed that a YOY?

This is what a marten uterine horn looks like the last week in March. Three young. Gulo when would you expect for these to be born. Looks like april to me.



The blastocysts on a January wolverine. Three young forming.


This was an interesting head shot. Notice the indent on the growth in the right photo.

White17...
Sorry I'm not being real clear. On male marten, YOY animals will have the sagittal crest visible all the way back, the full length of the skull, or the masseter muscle closure will only be about 3-5mm (where the muscle has coalesced together) from the rear end of the skull (from the lambdoidal crest). The remainder of the sagittal crest is visible, and there is usually a gap between the muscles which may be several mm wide. FamilyTrapper's last images above, if indeed they are both males, both of them are YOY animals. That is, very little muscle closure. On the other hand, if that last photo is of female heads (I can't tell scale), the one on the left is undoubtedly a YOY, while the right one is probably a YOY, but should look at uterus size for verification.

FamilyTrapper...
Really nice photos! Uterine scars (again, not persistent in marten, so lets not go there) are where blastocysts (developing embryos) have implanted on the uterine walls and go through their development until perturition (birth). It is the number of fetuses that developed, but not precisely the number of young produced. You've still got to take into account resorption of fetuses in times of stress and stillborn fetuses. Gets real complicated (sorry; I guess I'm an egghead).
The blastocysts that are flushed out of a marten uterus are a little less than 1mm in width. Thus, you pretty much need a dissecting scope to verify numbers. I usually flush them (with water, flushed through a 3-4cc syringe, 20-ga. needle, inserted near the ovary and flushed down through the uterus toward the vaginal end) into a petri dish with water. Under good light, and if your eyes are better than mine, you can see and count these little dudes.

I feel at this point that I should provide a disclaimer. In actuality, guys, I'm nothin' more than a trapper, tryin' to do the best I can to maintain trapping, yet maintain the resource the best way I know how. All this biological mumbo-jumbo really does have a point to it.....

FamilyTrapper...
On your top photos, I agree. Looks like an April, maybe early May, parturition date, based on the size of the fetuses. That's pretty advanced fetal development for March. Usually, they're not that far along.

On the other hand, you are down there in the delta country...

The female with young was taken with a 22 the last week of march. She had refused a set and was climbing a tree near the set. My son got pretty excited about it that was the end of story. Had I know I would have left her. Does one flushing push out the blastocysts? What is the most you have found in a female. What seems to be the average?

Very interesting! Wish some of my college courses would have been this interesting. And my wife thinks I'm wasting time when I'm "on the Trapper's Forum again!"

Keep the info and pics coming!

How do you go about getting teeth aged? Is it something you can get setup to do with F&G?

Does one flushing push out the blastocysts?
Yes, one flushing per each uterine horn flushes out all unimplanted blastocysts. You can usually talk a local high school into letting you borrow a dissecting scope for counting.

What is the most you have found in a female. What seems to be the average?
I believe the most ever encountered was 6. My sample size is well over 1,000 adult females flushed over a 20+ year period. The average varies from year to year, but overall, is probably between 2 and 3 blastocysts.

How do you go about getting teeth aged?
My recommendation is Matson's Lab in Milltown Montana. Gary Matson has more experience than anyone in doing this. He used to take teeth directly from trappers, I believe, and it also used to be about $8.00-$10.00 per tooth. Turn-around time is about a year, so you have to be patient. At this point, I'm not certain if Craig Gardner (Furbearer biologist, ADFG, Fairbanks) is collecting a large sample to age. From what I understand, his funding has been cut dramatically. You may also want to see what White17 has in mind.

This past spring Gulo and Craig and I exchanged a three-way email about the marten on my line and their ages. Craig had expressed that he was seeing similar results (very low juvenile counts) in the critters he was cutting up. He also mentioned a low blastocyst count from some areas. (I think we may be seeing the fruits of that this year but thats nothing more than an uninformed opinion) Craig's heartburn was that he had no funding for tooth aging and maybe no money to continue this particular work.

It seems to me that this would be a worthwhile thing for us to help out with funding. I think it would be imperative that Craig have control of the funding rather than the Department. Maybe Gulo can tell us how to structure things so that is attainable.

Anyway, I think it's something that could eventually benefit the resource and in the long run, trappers. I have no idea how much we would need but again Gulo can provide guidance there.

So I think this would be a good place and time to discuss that and see if there is any interest.

Take a poll, wise one.

Is this just your experience, Ken? Has this been tested in other areas of the state? Are you getting a large sample of your catch actually aged, or is your info coming from using skulls.
mt

That's my interpretation from several hundred teeth aged over several seasons on my line Mike. I'm pretty certain that the average could only decline to a certain level before there were no more to trap.

This assumes a more or less constant rate of in-migration from refuge areas surrounding the trapline. I suspect it would change measureably in the situation that now exists on my line. I believe some external event has moved my population to some other area and now critters are beginning to move back in. They seem to be overwhelmingly adults. It would be interesting to see how those ages compared to previous average ages.

So where do I place my bid for "white17's February 2011 trapline adventure" to benifit marten research??

You need to survive 2010 first. But you do have a point. We should probably let you make the first bid on the next auction.

It's not the first bid I want the rights to!

HAHA You'll have to earn the last bid.

LOL.
Don't I know it!

It was good training for you.

Gulo: does the development of the masseter muscle depend at all on what the critter is generally eating ?

Wow $8-$10 a pop. What does it entail? Just a cross section and ring count? Polishing? Just a guess.