Posts Tagged With: den

Fisher Motion Pictures

Over the last few months, our cameras placed around fisher dens have captured loads and loads of pictures (over 18,000).  We often post some of the better photos to the blog, but there are many that don’t make the cut.  The main purpose of these cameras is to document kits, but in addition they collect all sorts of other information.  We often see various predator and prey species around the dens, males visiting during breeding season, mom bringing back food items, as well as many photos of females simply entering and leaving the den on their daily travels.

We sift through all of these photos, recording what is in each one.  Doing this gives us a little insight into life around the den.  When all the photos from a specific camera are strung together and played like a movie, they are pretty cool to see.  I’ve put together 3 short “motion pictures” from a few of the dens that we collected photos from (the links will take you to a Youtube video):

21392 – Over a month and a half of pictures from the natal den of this two-year-old fisher.  She is a native Stirling born fisher, believed to have had one kit this year.

21FB6 – Pictures from a maternal den of one of the year-2 translocated females.  This spring was her third time denning on Stirling.  This den was one of her maternal dens she first used back in 2011.

23955 – These photos are from a maternal den / rest tree found in mid-July, when the kits were pretty mobile.  23955 is also a native born fisher and this was her first time denning.


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It’s hard to believe that 2013 marks the 4th year that we’ve had fishers on the Stirling district denning and giving birth!  Over the last couple of weeks we have been busy trying to locate dens.  As of today, I am happy to report we have confirmed that 9 of the females we are tracking have settled into behavior consistent with denning (using the same tree over multiple days).  So far we have located dens from 4 of the year-2 translocates, 2 from year-3 translocates, and 3 from fishers that were born on Stirling.  We found the first den this year on March 18th, the earliest recorded over the 4 years!

As Colin pointed out a few weeks back, this year marks the first time that we are able to document fishers that were born on Stirling giving birth to kits of their own.  It is very encouraging to find 3 of these individuals in dens!  We are hoping that within the next week, we will have a fairly complete picture of denning throughout the district (well, those we are tracking).  There are still a couple of fishers that seem to have not settled yet, or that we haven’t been able to get to.

As we are starting to collect pictures from the remote cameras, we have been seeing a lot of males visiting the dens.  In fact, we have documented males at each of the 7 dens that we have retrieved pictures from, with many having multiple males visiting!  Included in these are a few males which have no collar, or collars without any transmitter.  We definitely missed a few during the fall trapping!

I’ve included a slideshow with some of the more interesting photos we have collected so far.  Hopefully it won’t be too long now before we start seeing some kits!

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Love is in the Air

Okay, so maybe love isn’t the best choice of words.

The other day I was searching for the natal den of one of our trans-located females.  Having narrowed the signal down, I thought I knew where I needed to go in order to find her.  As I was riding on the ATV past an old road, I caught a “fisher log” out of the corner of my eye.  Now I often see fisher shaped rocks and logs, and 99 times out of 100 they are just that.  This time however, as I backed up to get another look, this particular log turned around and loped off!

I quickly grabbed my gear and started walking after the fisher, thinking it was probably the female I was looking for.  As I walked a ways down the road I realized that although I was extremely close to the female, her signal indicated that she was not moving.  Just then, one of the Argos collared males appeared and started to approach me!  He got about 15 feet away, then moved up-slope towards a large tanoak.  After sniffing around the base of the tree for a few seconds he slowly walked off.  Not surprisingly, this turned out to be the tree the female was in!  This was the first time I have personally spotted a male at a den (although it isn’t too uncommon among the field crew, and our cameras detect it frequently).  It was certainly nice of him to lead me to the tree she was in.

The spring denning time coincides with the breeding season for fishers.  For us on the ground, it is probably one of the best opportunities to spot the males out in the woods.  Males are busy seeking out the females, and just like in this case, often end up at their dens.  I put up a camera pointing at the tree, and it caught a cool series of pictures.


The male in the picture is not the male that led me to the den.  He is un-collared, and appears to be quite a bit smaller than the one I saw there.  It wouldn’t surprise me to catch some larger males visiting the den in the next few days.  This particular female has been in the same tree for a few days now, indicating this this is probably her den.  We are starting to see many of the females we are tracking settling into denning behavior, but more on this in a few days!


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In The Field With Fishers

Our situation on the ground has been a little hectic over recent months and some of you avid followers may have been feeling a little neglected when it comes to field updates. Well, fear ye no more, I shall share a few details regarding the animals we are currently tracking on and around Stirling as of late February.

We are currently tracking 23 Fishers with active telemetry transmitters on and around the Stirling District. Of these, 16 are fitted with VHF transmitters that we must actively track. 15 of these animals are females wearing VHF collars, the other is a male born on Stirling in 2012 who was given an implanted transmitter due to his age and potential to outgrow a collar. The remaining 7 animals are males of greater than 1 year of age fitted with ARGOS collars, these collars collect locations via satellite and can be conveniently tracked from the comfort of our desks. A breakdown of these animals by year of birth/translocation can be seen in the table below.

Right now we are unable to account for 3 more animals (2 females, 1 male) with potentially active transmitters who we hope are still going about their business out there. They were all born on Stirling in 2012 and have been missing for over a month. Sometimes such animals turn up in unexpected places (see previous post “The Grass Is Always Greener”) or are recovered during our trapping efforts and sometimes we never learn their ultimate fates. Either way, they are young and wild and all we can do is to keep searching.

You can get an idea of the spread of our animals across the study area at the moment from the aerial photos below, to give a little perspective the lines on the image represent the county lines of Plumas to the East, Tehama to the west and Butte in the South.

Female locations:

Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

Male locations:

Year 1 translocates in Purple, Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

Year 1 translocates in Purple, Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

As you can see we have a pretty wide spread of animals across our study area at the moment, and we are aware of uncollared individuals in many of the intervening areas. As denning season creeps up on us we will be kept busy trying to keep tabs on everyone, this year is shaping up to be an interesting one with more potential dens than any previous year, I will update you all with some of our denning predictions in the near future.


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Kits, Part Deux!

We’ve recently got some more pictures back from den cameras and verified a few additional kits!  Thus far, we have seen kits from 5 of 9 denning females, for a total of 9.  The other females have either not moved dens yet, or made it past our cameras without triggering them.

714C2, Kits 1,2, &3.

First came pictures of three kits from female 714C2, who was released last fall.  She moved these kits back into her first den (though possibly a different cavity) for a few days, which was something we hadn’t seen before.

Next we saw two kits from 2189C, an animal who was also released last fall and has since made her way to the northeast side of the property.  She has denned up fairly high at ~5500 ft., and interestingly there was a marten that came by her den!

Some of the coolest pictures (in my opinion) from this denning season came from cameras on 182F4’s den.  She brought her kits down the tree and allowed them to explore for a few minutes before they headed off to the new den (only about 50m away).  It appears that females are beginning to spend less time in dens and more time out foraging, which makes the task of finding new dens more difficult.

Anyway, here’s the pics.  Enjoy!


2189C’s Kits 1 & 2.


182F4 letting the kits explore.

Keeping a lookout.











182F4’s kits playing.

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We recently got confirmation of the first kits of 2012, as a couple of female fishers moved their dens!  Although we suspect that nine of the females we are tracking have denned and had kits, it’s nice to get some actual photos of them.

93B5A’s kit.

The first of the year belonged to female 93B5A, who was released in the fall of 2010.  This is exciting because even though she did appear to den last year, we never got any pictures of her kits.  The picture was taken only two weeks after we found her den, and as you can see the kit is pretty small.

The most recent picture of a kit came from fisher 20058, an animal that was released last fall.  This kit appears to be larger, which isn’t surprising as it was moved six weeks after we first suspected she had denned.  It is interesting to see how fast the kits are growing at this stage.

We only captured one kit on camera for each female, but it wouldn’t be at all surprising to learn that they have more.  Although the cameras we use are pretty good, fishers have a habit of getting around without triggering them.  In the case of 93B5A, she returned to the den tree shortly after moving one kit, but the camera didn’t detect her coming back down again.


20058’s kit, another view.

20058’s kit.

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Den Update

As of today, we believe 9 of the female fishers which we are currently tracking have denned up.  These include all but one of the animals released in year two (5 of 6), and all but two from year three release (4 of 6).  During our trapping effort from last fall, we captured 5 juvenile females that were born on Stirling.  None of these appear to be denning yet, but this is not too surprising as they are all young (1 or 2 years old).

714C2 returning to den with prey.

It is still a little too early to say that there aren’t any more dens out there that we haven’t found.  Some of the fishers we are tracking are in remote areas, which we cannot get to as often as we would like.  Additionally, many times we get out and locate them, they are out foraging.

We are starting to get some more pictures back from the remote cameras we aimed at the dens.  Already we have documented males visiting many of the dens, females returning with prey items, and other species besides fishers at the dens.   Here are some recent pics:

Raccoon descending den tree of 21FB6.

Male at den tree of 182F4

21FB6 returning.

Natal den of 20058.



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The Secret Lives of Fishers

A couple of our remote cameras captured a rarely seen fisher behavior a few days ago.  Check it out:















They’re a little grainy, but the top two pictures show two fishers coming down the tree, while in the bottom two they appear to be mating at the base. These cameras were pointed at the suspected natal den tree of fisher 18871.  Many of our cameras at den trees have captured males coming and going, but to actually see them mating is pretty rare.



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DENizens of the Trees

In the last 2 weeks we have managed to confirm that at least 5 of our females have settled into patterns consistent with denning behavior. We detected the first on about March 21 and that is the earliest we have detected a female in a den over the last 3 seasons (more on that  later). Three of the females were released in year 2 of the translocation. One of those females did not den last year and 2 did. The other females were those released in year 3. This is positive because it shows that the females from last year found mates and appear to have had kits. We demonstrated this last year with first year animals, but observing it for the second year adds data and understanding to important population processes. Matt observed a male fisher at female 1F111’s den tree already this year. This was a female released in year 3  and the den is about 11 km east of where we released her. I am still amazed that males show up at den trees seemingly right after females establish them, but since that is a male fishers specialty I guess I shouldn’t be surprised at all.

Black oak den tree

The dens are spread across a big swath of the district. From the west side in the Big Chico Creek Drainage to the east side near highway 70. We even have one female denning on the north side of Deer Creek. We still have a lot of females that have yet to den so it should be interesting to see the distribution of their dens when all is said and done.

Den tree (on right) of female 1F111

The first two years of the project  the earliest we ever found a den was March 23 and most were found after April 1. This year we have found 3 dens before March 23 and another 2 before the 26th, One reason for this might be that we have better access to where females are because we have had relatively little snow accumulate over the winter. The last two years we were snowmobiling/snowshoeing into dens through much of April. Alternatively, the relatively mild winter might have simply allowed females to den a little bit earlier (some anyway) because they were in a better condition. At least three of these females appear to have never given birth before (based on past tracking and physical examination), and this could influence their body condition and timing of birth. All of this is speculation of course, and the bulk of females have yet to den so we might just be observing natural variation in timing of births. It will be interesting to see if other studies detect earlier than usual denning behavior.

We’ll be putting cameras on all the den trees we find to document when females move their litters to maternal dens and to make minimum estimates of their litters sizes. More information to come….

A view of the area immediately adjacent to a fisher den

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The Great Kit Debate

In a somewhat desperate bid to up my posting rate I’m going to revisit old ground in this post and return to a brief email debate from last April.

And so a brief background is in order…

As we build up to this years denning season we have begun the task of collating and analyzing our camera data from the first two denning seasons on Stirling. As many of you may know the season really begins to heat up in early April as we confirm natal dens (a natal den is the den in which a female gives birth to her kits) by performing walk-ins on stationary females. It is usually on the second walk-in to a given tree that we consider the female has indeed denned. At this point we set a series of remote cameras around the den structure in order to passively monitor the females activities. Through the denning season a female Fisher will usually progress from her natal den through a number of maternal dens (a maternal den being any den occupied after the natal den). Thus one of the most exciting things we see on our cameras is the female carrying her kits out of the den, this gives us a great opportunity to count the number of kits.

So here the debate arises. While going through our pictures of female 17582’s natal den from the 2011 season I came across some familiar images, the first image is of 17582 moving her first kit from the natal den to her first maternal den roughly 100 yards away. Nothing too contentious there.

The picture below was taken 20 minutes later and appears to show her moving a second kit, or potentially a second and third kit at the same time, as the wily Roger Powell contended.

And here is the same image expanded;

So I ask your opinion,


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