Updates

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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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.

69940map

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!

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Young of the Year

It’s been nearly 3 months since we found our first dens of 2015, and we’ve been busy continuing to try and track females and get pictures of kits.  It hasn’t always been easy, and many of the females this year managed to move out of their natal dens unseen.  However, our persistence has finally been paying off over the past few weeks.  So far, we have confirmed a total of 19 kits from 11 denning females!  This averages to 1.7 kits per female, which is on par with what we have found in previous years. Mostly we’ve seen fishers with either 1 or 2 kits, although we did confirm a 3-kit litter from one female.

It’s enjoyable to me to see how fast the kits are growing. In just the last couple of weeks we have started to see some of the kits climbing down trees on their own, and playing around outside of dens (with adult supervision).  In some instances, the kits seem to be following mom to the new den instead of her carrying them.  It also appears from the photos that the females are starting to bring back more prey items to the dens.

At this point, it is very difficult to pin new maternal dens down. The females are out foraging the majority of the day, and since the kits are becoming more mobile it is probably easier for her to pack up and move to a new home.  There are still a couple of females from whom I think we have missed seeing a kit or two.  We will continue to opportunistically walk in on everyone to try and get as accurate of count as possible before the juveniles dispersal in the fall.

Below is a slideshow of many of the kits we have confirmed thus far. I have tried to put them chronologically so you can get an idea of just how fast these fishers are growing up. The first picture is from April 3rd, and the latest from June 8th.  Also, a camera from a log den found about a week ago captured hundreds of images of a female eating a squirrel while her kits were around! I put these into a slideshow you can watch HERE.

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Happy Birthday Dear Fishers…

Likely a little belated in most instances (and possible early for a few others), but mid-March to early-April is the time when fishers’ give birth to their kits. Our oldest on-air female just turned 8 years old, while the oldest male we are tracking turned 9!

This is a busy time of year for us on the ground. We try and locate the den-sites for all females who are old enough to have kits. In addition, we set up and maintain motion-censored cameras at all of the dens, attempting to get a glimpse into activities around the den as well as detect kits once a female chooses to move to another den.

This year, we are tracking 18 females who could potentially den and have kits. Thus far, 13 individuals are exhibiting behavior consistent with denning (staying in the same tree over multiple days). In addition to females giving brith, spring is also the time of year when breeding occurs. Males are busy roaming around trying to find the females, and often end up at their dens. As such, our camera’s have been takings lots of really interesting photos.

I made a “motion picture” from the photographs of one remote camera over the course of a few days at a natal den, which you can view HERE.  Also below are a few pics from various dens so far. Enjoy!

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Shh! Don’t Wake the Bears

A fair amount of the sampling we conduct throughout the year includes us using some kind of bait and/or lure to try to attract fishers to a certain area. As you might guess, many other animals are attracted to these smells and the prospect of a free meal. Some of these critters may end up stealing our bait or getting caught in traps (thus preventing fishers from entering). However, this is more of a slight annoyance, and pales in comparison to the usual impact of the black bear. Throughout much of the year black bears are a common visitor, and their presence is often obvious. Not many other animals can completely disassemble a wooden/metal trap, or tear a track plate box into 10 pieces. In fact, bears cause so much destruction, we frequently use a word that you may have never heard of to describe the carnage:

beared, v. having been altered from function by the actions of a bear.
“The trap was beared, and it took Kevin 20 minutes to find all of the pieces that were strewn about 50m downslope of the original location.”

We’ve tried to construct ways to mitigate their impact. At one point while doing camera surveys, we even drilled 2x4s to trees about 8-10ft up. These extended ~6ft out away from the trunk, and bait was hung about a foot above the end of the board. These “run poles” attempted to allow only a small, good tree climbing animal access to the bait. Many bears were unfazed by the challenge, and eventually would succeed in getting the free food. Don’t get me wrong, I still like bears. They are awesome animals and I always enjoy getting a glimpse of one out in the woods. However, they do cause us lots of frustration. In the end we usually just grin and bear it, because there really isn’t much we can do to stop them.

Throughout the winter, most of our time is spent simply trying to get daily estimated locations of fishers. It is also a time where we catch up on going through our massive collections of pictures from remote cameras that were taken during other times of the year. So although many of the bears are still sleeping out in the woods and not currently bothering us, we relive their destruction (and ultimately our frustrations) that are caught by our cameras.

I thought I would share a few photos of some of the bears more destructive moments.

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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.

DSCN0837_1

First male captured.

Getting a weight.

Getting a weight.

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Fisher Frenzy 2014

We recently wrapped up our month-long fall trapping event (aka Fisher Frenzy).  This is the 4th year we have conducted this large scale trapping event, and 2014 proved to be our most successful to date.  Over the course of the month, we were able to capture 32 individual fishers!

We conduct this trapping effort for a variety of reasons.  First and foremost, it allows us to affix radio-collars on fishers.  Most of our collar’s batteries tend to last a little over a year, and thus the collars we put out in 2013 do not have very much life left.  The new collars we put out should last us until next year at this time and allow us to track the fishers throughout the year.  We also learn a lot by examining the fishers we do catch.  We can get an idea of overall condition, age, past reproduction, parasite load, and old or new wounds.  Sometimes, we even get the shock of seeing something completely unexpected, like imbedded porcupine quills!

On a more personal note, trapping is the time of year that we actually get to see fishers (as well as some of the other forest mesocarnivores) up close and personal. This is immensely enjoyable to me, as most of the year it’s rare even to get a glimpse of the fishers we are tracking on a daily basis.

As in previous years, we spent the first two weeks trapping the east side of the district before moving to the west side for another two weeks.  On the east side, we totaled 36 fisher captures of 24 individuals (18Female:6Male).  11 of these were fishers that we had never captured before (6F:5M).  Our success slowed down on the west side of the district, but we did manage 17 total fisher captures of 8 individuals (5F:3M).  Of these, 4 were fishers who had not been caught before (3F:1M).

In total, we ran over 2,700 trap nights!  We recaptured 17 fishers from previous years (14F, 3M), as well as picked up 15 fishers (9F:6M) that we had never caught before.  Our overall trapping success rate for fishers was 1.9%.  Besides fishers, we also capture quite a number of other animals in our traps.  We managed to catch 45 spotted skunks, 32 ringtails, 15 grey foxes, 3 striped skunks, 2 raccoons, and even 1 bear cub (luckily mom didn’t seem to be around).

Every year, there are a few wise fishers that manage to evade our traps.  At the end of trapping, we had 4 known on-air fishers that we did not catch.  Adding those animals to the number of fishers we did catch gives us a “minimum known alive” population size of 36 individuals.  Of course, it’s likely we are not capturing all the fishers that are out on the landscape (we are also not able to trap every area we would like to because it’s not logistically feasible).

In order to run trapping at such a large scale (~100 traps open per night), we require a large amount of personnel, time, and effort.  This year, we had over 25 people come out to help us with our daily trap checks and examinations! All of the project cooperators (California Fish and Wildlife, North Carolina State University, Sierra Pacific Industries, US Fish and Wildlife Service, and Wildlife Conservation Society), made large contributions to help pull this event off.  A HUGE thank you to everyone who gave their time and effort to help make this year’s trapping a success!

Here are a few pictures from this year:

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The Most Wonderful Time of the Year

Yes, I know the saying is generally reserved for a little later in the year, but that only applies to people who haven’t had the pleasure of trapping fishers in the fall. For those of us that have, and are about to again, the fall trapping season really is a marvelous time to be alive and doing field work. October 13th marked the beginning of our annual large-scale trapping and population monitoring effort on the Stirling district. Some have called this hectic rush to capture fishers the ‘fisher-palooza’, the ‘trapping blitz’ and sometimes just ‘fall trapping’, but I’ve always been fond of the term “Fisher Frenzy”. For those of you that have experienced it you’ll understand why I prefer this term — it really is a month-long frenzy. It is extremely enjoyable to set traps, capture and process fishers but it is always a grueling period where everyone is constantly busy and slightly stressed about everything that is going on.

On a daily basis we are deploying, checking, baiting, and hauling over 100 traps scattered across much of the study site. This may not seem all that bad except that it is critical that we check each and every trap once a day, at a minimum, and it takes a lot of thought and planning to make sure that we get this done. Each trap is usually about 1 mile from another and it can take 1 person half a day to check just 20 traps. In addition to fishers we catch foxes, ringtails, opossums, raccoon, and the bears are always investigating, rolling, and sometimes damaging traps too. If it snows or rains then that adds to both our comfort levels (have you ever spent all day checking traps on an ATV in the rain?) as well as the possibility we will not be able to get into our trap sites easily. The field crew (led by the intrepid Kevin Smith) has spent weeks fixing traps, finding locations, getting bait, and organizing routes and people. So, you can imagine they are already a probably a little stressed and maybe even sleep deprived, but they are doing an outstanding job.

I suppose I have’t made the experience sound all that wonderful to this point, but the reality is all the preparation and the daily grind is a very small price to pay for the experience and information we get from the fall trapping effort. Trapping fishers allows us to see, and examine, fishers that have been out on the landscape for the last year (or longer) and evaluate how well they are doing. It also introduces us to new fishers that have been born on Stirling and to get information on their condition, age, reproductive status, parasites as well as genetically identifying them. From the trapping data we can evaluate how much the population has grown, or shrank, and we can collar new animals so we can continue to track them.  So, we learn a lot about the fishers, and the experience is a great time as well. Being out in the woods and setting and checking traps is, at least for me, one of my favorite things about field work and I enjoy the experience immensely. It is also a time when the different members of our team get to be around each other and work together for a common purpose. We learn a lot and generally have a great time. So, as you read this some member of the crew might be leaning over a closed trap and hearing the muffled chuckle that a trapped fishers makes and seeing those lovely green eyes staring back at them from the trap. We should all be so lucky! With luck we’ll be able to keep everyone up to date on our trapping success over the next few weeks.

I’m enjoying myself like a kid at Christmas with a bunch of presents that are sitting out in the woods just waiting to be unwrapped. Indeed, it is the most wonderful time of the year.

ANF

Categories: Field Day

All Eyes On Me

Throughout my career in wildlife work, I have had a number of awe-inspiring experiences.  Often, these are times when I’ve managed to catch a rare glimpse into the life of a wild animal.  While tracking fishers, I have had a few awesome encounters (many of which have been written about in previous blog posts).  A couple of weeks ago, I was fortunate enough to have two experiences back-to-back which I know will stick with me for the rest of my life.

F8B8Dwithkit

A little blurry I know, but that’s 2 fishers!!

The first of these happened during a opportunistic walk in of fisher F8B8D.  This fisher was among the first group of fishers translocated to Stirling back in ’09-’10.  A few months after her release, her transmitter failed, and we were left wondering what happened to her.  To our delight last fall, we re-captured her!  Since that time we have been faithfully tracking her and learning what areas of the study area she has settled down in.

As the VHF signal grew stronger and I knew that I was getting close, I looked around at the nearby trees for any sign of her.  About 30ft up in a Douglas fir, I noticed a nest.  I’ve found fishers resting in nests many times before, so I moved upslope of the tree to get a better look.  Sure enough, I saw the tell-tale silhouette of a fisher head. I got my binoculars out, and to my surprise I found not one, but two fishers returning my stare from the nest!

The very next day I had a similar experience, only this time it was with a different fisher (36A8B, a two-year old).  This time as I got close, I looked up at a nest and again saw two fishers staring back at me.  As I was looking for a collar to try and identify who was who, 36A8B came into view from a higher branch, made her way down the tree, and briefly joined the two kits in the nest.  I was staring at three fishers!

It’s always very exciting to get a glimpse of a fisher.  Even though I often get fairly close to them while conducting radio telemetry, they are very hard to see, and are usually resting in the cavity of a tree or run away when I try to approach.  This is the first (and second) time in my many years of tracking to get to see a mother with her kit(s)!

Besides from just getting an awesome look at five fishers in two days, these two particular cases were also helpful for us. Both of these females were suspected to den this spring, but we were never able to confirm kits from them with remote cameras.  These visuals confirmed that they had reproduced this year, and have raised at least some of their offspring to this point!  By this time the kits are getting to be pretty large, with the juvenile males being about the same size as an adult female.  It won’t be too long now before the kits will disperse and be on their own.

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Warm winter nights….and happy endings.

When you wake up in the morning, you never really know what the day is going to have in store for you.  We do, after all, carve out our niche in the world by following the daily habits of small furry critters in a predominantly wild landscape.  We often grow attached to our fuzzy wards (how could we not?).  So when something in our data collection portends trouble for one of them, we mobilize to see what we can do.

Males that we capture and deem healthy enough to carry the weight sport ARGOS collars.  These collars communicate with orbiting satellites to determine the collar’s location and the satellites then relay location information via email right to my laptop.

There’s me in the corner!

Armchair biology.  Technology!  While this sounds like a road to obsolescence for field biologists, we still need to track the collar (and fisher) down when the data tells us something is amiss.  The collars are only on during certain times each day, and during this window the collar transmits once a minute to the satellites.  We’ve got a nifty receiver that lets us track it down via strength of the signal and distance from the collar as it transmits.

Male 190 was released in December 2011, and has been with us a little while.  He’s often seen at female den trees during mating season, and all in all, he’s just a sturdy, well built fellow.  It was distressing, therefore, to see some of the data from his collar suggest that he might no longer be with us.  To figure out if 190 was ok Julie and I looked into when the collar transmits and, lucky for us (sarcasm), it transmits from 5PM – 9PM and again from 1AM-5AM.  With the weather being wet as it has been for a time, we knew it was going to be an interesting hunt.  Just what we enjoy, if you can believe it.  We hoped for a dropped collar, and tried not to think about finding a carcass.  It was wet, getting dark, and we were heading into uncertain terrain.

Andria volunteered to go out hunting with me.  With the rain and the wet muddy roads, going in by truck was out of the question. Not to mention our only access was a long and partially closed road that would have required chainsaws, and more time (and daylight) than we could afford.  So ATVs were on the menu.  We knew the area we were headed to, and had a rough route planned (no one had visited this area since the rain, so all routes are tentative).  After dropping the trucks and heading out on the ATVs we began hearing the signal we had hoped for.  We continued on our pre-planned route, as a time or two doing this has taught me that signals broadcast up from a creek bottom can give misleading readings from a ridge top.  Along the way we had to move downed trees and rocks.

After getting all the way down to where our most recent data suggested 190 may be, we could hear no signals from the collar.  This had me daring to think that maybe, just maybe, he’s still alive – but somewhere other than where the recent points told us he might be.  We rushed as best we could back to the top of the ridge and posted up for a few minutes.  Lo and Behold, the signal boomed in to our receiver and continued to change in direction and intensity, quite quickly.  He was not far from where we randomly stopped, doing his thing and probably oblivious to our racket!  

Relief.   Elation.  High fives.  Back to the truck.  We were able to get out there, nose about, and determine that this guy is still hanging around, though probably weathering the worst of the rain in a tree hole somewhere, shielding the collar from reaching the satellites.  A good nights work, and home before 10PM.

 

UPDATE 2/15/2014:  Activity data from collar came through tonight and shows good readings across the board.  Sweet.

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