Posts Tagged With: Pekania

Growing Up Fisher

Over the last few months, many of the female fishers on Stirling have been busy raising their litters, and as such, we have been busy trying to keep track of them.  We see females start to den from mid-March to early-April, and try to document how many kits they end up having, along with what kind of structures they are using.  When we find a den, we put a few motion sensor cameras around it with the hope of capturing photos of kits when they move to a different den.  In addition to seeing kits, we sometimes get photos of other cool things like males visiting to breed, different prey being brought back to the dens, and visitation by predators.

Documenting kits is often a lesson in frustration and patience.  Fishers usually have multiple ways to get in/out of their dens, and many do a very good job of evading our cameras.  However, over the course of the summer, our persistence eventually paid off and we were able to document quite a number of kits from most of the known denning females!

From March 18th – July 15th, we documented 57 dens from 17 females.  We were able to confirm kits from 15 of 17 fishers.  Remote cameras placed around the dens picked up a minimum of 30 kits, for an average of 2 kits per female.  Like in previous years, the number of kits ranged from 1-3 per female.  The known rate of denning this year was 89%.

The length of stay in any one den varied greatly between individuals and dens.  We saw the first female move from a natal den on March 27th.  The last holdout stayed in her natal den until May 30th.  In contrast, one female had used 6 different dens before May 30th.

We often see mating behavior from late-March to early-April around dens, and this year was no exception.  Males visited the majority of early den sites, and cameras picked up breeding on multiple occasions.  In once instance, mating occurred over a 2 1/2 hour period!

Raising kits increases the energetic demand of fishers, who now have multiple mouths to feed.  Not surprisingly, we often see an increase in mortalities during the summer months from females raising young.  This summer we have had 3 females die who we knew were denning.  It is always sad when a fisher dies, and knowing that their kits will not make it is especially hard.  I usually reconcile this with the knowledge that we document a far greater number of kits than the number of fishers that die, and assuming many of these youngsters make it to adulthood, they should replace those we lost.

By this point in the summer, the juveniles are getting pretty big.  It won’t be too much longer before they disperse and try and make a living on their own.  Included are some pictures from this years’ denning.  I have tried to put them chronologically, so you can see the changes in kit size as the summer progresses.

 

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Categories: Updates | Tags: , , , , ,

On the Road Again

For much of the spring and early summer, the job of tracking most of the female fishers isn’t all that difficult. Denning females spend a lot of time in their dens, so we usually have a specific point for starting our searches.  When they go out foraging, we know they will need to return to their den eventually, and often aren’t found too far away from these sites.

As we move into June and July, the kits grow quickly and become more mobile. The time spent in any one den becomes shorter, and females are out and about more and more. Keeping track of them starts to become more difficult. Once August rolls around, we often observe some larger movements, many of which take the females outside of the areas we have tracked them over the last many months.

This pattern of females making larger moves around this time is something we notice every year, but the reason is not fully known. Possibly, this has to do with them depleting the easy food sources closest to their dens, and these moves take them to better hunting grounds.

Another hypothesis for this move is that females are taking their kits to the edges (or outside) of their ranges to let them become familiar with an area for them to “disperse” to. Especially for any juvenile males, it is not advantageous for them to remain near their mom’s home range, so making a move to get the kits away from her range makes sense. Whatever the reason, it’s fun (although often frustrating) to track them in some different areas.

By now, the juveniles should be very close to dispersing (if they haven’t already) and being on their own. We will begin our trapping efforts in a few weeks, and it will be exciting to see if we can capture some of these youngsters, especially in the areas that we are seeing the adult females traveling to.

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2015 VHF locations for 69940, a two year old denning female. Blue stars indicate locations from January until the middle of August.  At that point she took off to the southwest. Green stars show her locations from middle of August into the middle of September.

Juvenile fisher from the end of August. Getting big!

Photo of a juvenile fisher taken at the end of August. Getting big!

Categories: Field Day | Tags: , , , ,

Spot Trapping

At the end of our Fisher Frenzy last fall, most of us were pretty satisfied with the fruits of our labor. We had captured more fishers than in any of the previous years’ efforts, affixed all of our available VHF collars on females, caught a good crop of juveniles, and all of the fishers we examined seemed to be in pretty good health. What else could we ask for?

Well, there was one question that I couldn’t get out of my head – Where are all of the adult males? We only captured three, and knew of a 4th that was on the air but never captured. This is in contrast to 17 adult females caught during the same time period. Of course, we expect to find fewer males due to their larger home ranges, but only capturing three adults? Something seemed wrong here.

After we finished up our main Fisher Frenzy, the team here continued to run a small number of traps, attempting to target particular fishers that avoided capture. For most of December and January, we didn’t have much success. We kept recapturing fishers that we had caught during the Fisher Frenzy, but the target fishers wouldn’t enter our traps.

However, to our delight a couple of weeks ago, we caught a fisher that we had never seen before. It ended up being a large 4.8 kg male!  He was in excellent condition, and we put a collar on him. He was in an area that we aren’t currently tracking any other adult males (but we did have plenty of traps in this area during the Fisher Frenzy).

Starting to wake up.

Starting to wake up.

Dustin and Pierce monitoring the first male captured.

Dustin and Pierce monitoring the first male captured.

Fast forward three days later. In the exact same trap, another unmarked fisher was captured. Once again, it was an adult male! This guy was slightly smaller than the first (4.3kg), but was also in really good condition. We put a collar on him as well, and let him go.

Capturing these males was important for a variety of reasons. First off, it will allow us to gather some location data on them so we can see what areas they occupy. Secondly, it reinforces to me that there are fishers out there that can go undetected for years, and that we aren’t catching all the animals that are out on the landscape. We won’t know the exact age of these males for a while, but based on their size and developed sagittal crests, both of these guys were probably older than two. This means they avoided capture during the Fisher Frenzy 2013 and 2014, and possibly even 2012. Of course, is could be simply that they spend most of their time outside of the main Stirling tract, and were just now passing through the area for some reason (perhaps scoping things out as we get nearer to breeding season). We don’t have the resources to trap many of the areas adjacent to Stirling, so any fishers occupying those lands might go undetected. Hopefully their collars will give us many good locations over the next year.

Personally, it eased my fears of something more serious going on with the males. It’s hard not to go through all the doomsday scenarios after not catching very many. Possibly they simply aren’t as prone to entering traps as females, or maybe many males are partially occupying areas we don’t end up trapping. Whatever the reason, it was a welcome relief to capture these two guys.

Sean babysitting as he was starting to wake up.

Sean babysitting male #2 as he was starting to wake up.

Andria, Roger, and myself waiting for the drug to take effect.

Andria, Roger, and myself waiting for the drug to take effect.

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First male captured.

Getting a weight.

Getting a weight.

Categories: Field Day | Tags: , , , ,

On this day

Today (December 9th) is a special day for me. Five years ago today I recall walking down a snow covered mountain road holding one end of a wooden box that contained a fisher. Holding the other end of that box was Roger and right beside us walked Richard and Scott – also holding the ends of a box the held a fisher. Our destination was a small clearing in the forest where many of our friends, colleagues, and even members of the media awaited us. More precisely, they waited for the fishers. The two female fishers we carried in those boxes would be the first 2 fishers released as part of our translocation project onto the Stirling district. We placed the boxes near the edge of the clearing and opened the doors and waited, and then we waited a little more. All the humans eagerly waited for the fishers to emerge from those boxes, but the fishers had other ideas. I can’t say I blame them. Having a bunch of beady-eyed humans looking at you can’t be a fun situation for a fisher (or any other creature either I imagine). I suspect we all, especially the members of the media, had a great illusion that the fishers would emerge promptly and slowly, pose for a few pictures, and then saunter away at a leisurely pace while we snapped pictures and looked on in awe. The reality was quite the opposite as both fishers, in their turn, streaked out of their boxes as a flash of brown into this new place they we hoped they could make into a home. Seeing the fishers run off gave a sense of great accomplishment and wonder but also of great responsibility and future hard work. I suppose Scott provided the most sobering perspective of the day (to me anyway) when he simply said “There are now fishers in the northern Sierra”. Yep, there sure were and that meant that we had to keep track of them, study them and also move an additional 38 fishers over the next 2 years.

Hill releasing fisher

Releasing a male fisher in December 2009

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Female fisher looking out of release box

Two years later on December 9th I was once again standing in a big circle of people waiting for fishers to come out of wooden boxes. Once again the media (see link for one article and some pictures) was there as well as friends and collaborators of the project. The outcome was much the same as fishers sat in the boxes refusing to leave and when they finally did they fled with extreme expediency. We released 2 females and 1 male, and they would be the last of the fishers translocated to Stirling. Not all the releases were met with media attention or lots of people milling around waiting to take pictures. In fact, most fishers were released with just 1 or 2 people looking on and waiting. Personally, I prefer a small release entourage. In all cases, the releases were the easiest part of the whole process.

It might take me an entire book to write about the tremendous effort that it took to get fishers to Stirling. There are myriad stories about trapping, handling, and transporting fishers. There are just as many about long meetings and phone calls where we considered all the risks and benefits and tried to decide the best course of action, and for each story I have the rest of our team might have 20 more. Yet, all those stories and experiences would only tell a small part of the entire story, because there were literally years of planning and discussion that went into developing and creating the project and the collaborations that made it all work. Most of that happening long before I ever even knew about the project. So, while I consider December 9th the birthday of the project we should always remember that it had a very long gestation as well, and that process went without fanfare or appreciation. The days we released fishers, and how those days came to be, are only one part, and perhaps the least important part, of what our project is all about.

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Some of the team handling a fisher before release

transport boxes in truck

Transport boxes full of fishers heading to Stirling

On December 10th, 2009, a day after we released the first fishers, Roger and I set out to find them. It was a mixed bag as we found one female within 1 km of the release point and had no luck finding the other. It took a few days, a few weeks actually, but we eventually found the other female. We tracked both of these females, as well as 7 other released in late December and January of 2010, throughout the spring. Both those two females survived and produced kits the first year as did most of the other females we tracked. Since that day we have spent nearly every day for 5 years looking for fishers to understand the specifics of how and where they live and reproduce. Of course, “we” isn’t Roger and I anymore. “We” is now a large number of folks that work, and have worked, in the field collecting data, and without them the project would not continue. It is also all the people behind the scenes and behind desks and telephones, in front of computers, in laboratories, and in many places and roles that make the project continue to work. The project would have failed a long time ago without all those many people and they all deserve a great deal of gratitude and appreciation. We continue looking for fishers and learning about their lives and ability to survive and reproduce on a landscape managed primarily for timber production. We don’t know everything, obviously, and though we’ve made great strides more information, time, and thinking is needed to fully understand the dynamics that drive fisher populations on Stirling. Nevertheless, five years later we know that there are STILL fishers in the northern Sierra Nevada.

Categories: Uncategorized | Tags: , ,

The Class of 2013

Over the last few weeks we have been observing many of the females moving from their natal dens to maternal ones, and just as we had hoped, some have had kits in tow!

The first fisher kind enough to show her kits this year was 714C2, a year-3 translocate.  This wasn’t too surprising to us on the ground, as this female seemed to constantly move dens last spring.  We recorded photos of her bringing two kits down the natal den tree.

The next three animals to move were all year-2 translocates.  Two of these, 21FB6 and 18871, have denned all three years since their release and we have documented kits from them each year!  93B5A, the oldest of the females we are currently tracking, just turned 8 years old!  This is also the third year she has denned on the Stirling district, and the second we have captured her kits on camera.  All three of these fishers have had a minimum of 2 kits each.

The last fisher that we found had moved from her natal den was 209DD, one of the females who was born on Stirling!  Her kits are the first we’ve confirmed from a fisher native to this district!  It appears she has also had a minimum of 2 kits, however the second picture isn’t as clear as we would like.

We have a couple of females that are still using their natal dens.  The amount of time a fisher will remain in the natal den seems to vary wildly from individual to individual and year to year, so its hard to tell when they will make a move to another den.  As is to be expected, a couple of the females managed to move their kits into maternal dens without being detected by the remote cameras.  Hopefully during their next move we will get some pics of them.  Until then, enjoy some photos of the kits we’ve seen so far!

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Pekania pennanti

The recent meeting of the Western Section of the Wildlife Society has been interesting. One important conclusion that Roger and I have reached is that it really is time to start calling fishers by the genus Pekania based on work done by research from Koepfli et al 2008. The alternative would be to put wolverines into the genus “Martes”, but such transitions seem unlikey.

Sure, if you still call them Martes pennanti we’ll still know what you are talking about, but this way is more fun (and accurate). Okay, I”m not sure I’m willing to completely give up on fishers being a “Martes” species, but the genetic work is interesting and something we should give serious consideration to.

-ANF-

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