Posts Tagged With: Northern Sierra

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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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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A Single Hair

It might not look like much. In fact, you might not notice it at all. But a single hair is all Jesse Hogg needs to help tell an important story. Jesse is working with the U.S. Fish and Wildlife Service and other project collaborators as a Klamath Basin Tribal Intern. Jesse began his work with us on the Eastern Klamath Study Area (EKSA) which straddles the California/Oregon border. The EKSA is one of several locations where project biologists captured and relocated fishers to the Stirling District of Sierra Pacific Industries. We are using non-invasive methods to monitor the fisher population of the EKSA to evaluate if the removal of the fishers we relocated was detrimental to the population. Jesse set, checked, and collected hair samples he found in devices designed to snag hair from local fishers. The genetic material stored in the root of hair can reveal an animal’s species and sex and characteristics used to identify unique individuals. After wrapping up a successful season, Jesse is now working in Stirling to help monitor radio-marked fishers.

The Klamath Basin Tribal Internship Program seeks to inspire young native community members to develop the technical skills required to monitor and manage species and habitats, to pursue college-level educational opportunities, and to succeed in conservation-focused careers. The program provides employment and professional development opportunities for members of six native communities of the Klamath Basin of northwestern California and southwestern Oregon.

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Miscellaneous Field Fun

The past few months have been diverse on the project for several reasons. Firstly, radio-tracking takes up a majority of the time spent in the field every week–checking in on up to 8 or 9 fishers a day in their respective territories means a lot of driving! However, before trapping started, finding radio-collared females was no problem, since we knew where each girl’s home ranges were. After the trapping frenzy this fall, it got a bit more hectic as all the females who were re-collared or new females who were fitted with collars began roving around the district like crazy, traveling several miles between days to different locations, and then moving again! However, it has since “settled down” quite a bit as all the females are beginning to settle nicely into their own ranges and are almost always found at any given time.

One of the other aspects of the project after the trapping frenzy of October/November was…yet more trapping! There are a few female fishers whose collars are dying, or who didn’t get captured during the first effort, that we are trying to catch before denning begins so we can check up on them (and give shiny new collars to!). So far, we have not had any luck catching “target” females but we did manage to catch a few incidental critters-as during the first bout of trapping!

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Here is a frisky spotted skunk…

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And a gray fox-

Ok, I can’t resist throwing in a female fisher captured from trapping in October! She is just too darn cute.

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As many of you may know, this is the driest California winter since records have started being kept. Despite this, about a month ago we did get a big dumping of snow, which halted field work for a few days while we waited for roads to be safe to drive again. This was an great change of pace as we were able to see tracks in the snow that we don’t often get to see.

Here is a monster of a black bear’s prints–and my size 8 boot to compare:

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Not far from this was a set of bobcat prints:

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After a while, the fun dissipates as the snow melts and all the prints meld together into an indistinguishable muddy mess. In some colder drainages, like this one on Big Chico Creek, the snow made the scenery quite enjoyable:

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But usually, there is always a “view of the day” no matter what the weather is like.

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In a few months, mother fishers will be denning and we will be able to see exactly where they will choose to rest with telemetry and motion-activated cameras-so stay tuned!

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Tracks, Hairs, and Bears, Oh My!

Tracking fishers using VHF telemetry is an extremely useful method for obtaining lots of different information about the animals, it’s also pretty fun! However, in order to implement this method, fishers must be trapped, handled, and fitted with a collar. As biologists, we love having the opportunity to work so closely with a species, but we also love the idea of gathering quality data without ever having to touch an animal. We call this type of data collection “non-invasive”, and it is the eventual goal of this project to use only non-invasive methods to monitor the fishers here on Stirling. In order to reach that goal, we recently ran a pilot study to test how well non-invasive techniques would work in collecting the information we need.

In mid-September, I ran this six week pilot study using track plate boxes fitted with hair snares (see “Field Methods” tab), as well as remote cameras. I placed 45 boxes and 15 cameras in the woods, spread throughout the western half of our district. I checked each box once every 6 to 8 days, collecting tracks, hair and photos that were left behind during that time. The baited boxes attracted lots of different visitors! Bears were especially fond of them; I commonly found the boxes ripped open and dragged away from where I placed them. Gray fox, squirrel, wood rat, ringtail, spotted skunk and even mountain lion are some of the other species I detected.

The most important visitors were the fishers, of course. Adult and juvenile animals, both male and female, investigated my boxes regularly. It appears the non-invasive methods will be a very useful tool for monitoring the fisher population here, and we plan on continuing the pilot study later this year. We are very excited to see what the data will tell us!

Below is a slideshow of images I captured using remote cameras during the study.

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In Search of a Den

The other day I found myself standing on a fallen log, trying to decide which way to go next.  The occasion?  I was attempting to walk-in on female 21FB6 in hopes of finding another one of her maternal dens.  I knew that I was close.  I had just passed the “sigh of relief” point; that grand moment in a walk-in when you know that you are close enough that the fisher isn’t likely to run away, making the trudge through a few hundred yards of thick understory vegetation (and in this case, millions of spider webs at face level) worthwhile.  Especially at this time of year, dens become harder and harder to locate.  It seems that females only spend a short time there before heading off again to forage.  As such, I was excited to get close and find her resting.

There were a couple of likely den tree candidates next to where I was standing.  To one side of me stood a good sized maple, which looked like it might contain a few cavities.  On the other there was a very large Douglas fir, which was tall enough that I couldn’t see a large portion of it due to the understory vegetation.  When you get very close to a fisher, it is often difficult to determine exactly where it is.  The signal tends to change dramatically with every step you take, leading you off in various directions for a few meters before abruptly changing again.  The solution I usually use to find the animal is to back a little ways away from the suspect trees, and circle them from a distance.  More than not with using this strategy, one of the trees eventually stands out as the more likely candidate.

21FB6 down in a log.

21FB6 down in a log.

Standing between the two trees, I was getting my strongest signal yet, but the signal kept changing.  One second, I would think she was in the maple.  The next, the signal from the Douglas fir was stronger.  I took a few steps away from the log and listened again.  To my surprise, this time the strongest signal didn’t seem to be emitting from either of the suspect trees, but from the log I had just been standing on!  I moved to one end which was hollow, and shone my flashlight in.  Two bright green orbs were reflecting back.  I had literally been standing directly on top of her!

This was only the second time that I have found a fisher resting in a fallen log, although I suspect it’s more common than we document.  I don’t believe she had any kits with her, but it was difficult to get a good look because she was far back in the log.  It is fairly rare (for me at least) to walk-in on a denning female who isn’t in her den, so I was a bit surprised to find her where I did.  Although I wasn’t able to find a den in this case, it was certainly nice to get a look at her!

Log 21FB6 was resting in

Log 21FB6 was resting in.

View of another female resting in a log from few months ago.

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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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To Den Or Not To Den?

That is the question. That time of year is rapidly approaching once again, expectant mothers on and around Stirling will soon have to pick their spot and settle down to the task of raising kits. The den season, particularly the early rush to pinpoint natal dens (those in which a female gives birth as opposed to the maternal dens she will use later in the season) is one of our busiest periods on the ground and from a personal perspective, one of the more rewarding.

This will be the fourth season in which Fishers have denned on Stirling since the reintroduction began and again it offers some potential milestones for the project. We have already seen the birth of the first kits sired on the district, the one to watch out for this season is the potential to confirm the first litters born to females native to the district. Although it is very possible that this happened last year we were not actively tracking any females born on Stirling who were potentially reproductive during the 2012 den season. Currently we are tracking 4 such animals and barring any mishaps we expect to locate natal dens for each of them should they give birth this season.

From the table below you can see that this year we are tracking 11 females which we believe could reproduce. Besides the 4 animals mentioned previously we have 5 year 2 translocates, all of which have produced kits previously and 2 year 3 translocates, only one of which has reproduced before.

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Females with the potential to reproduce in 2013

As a point of comparison, ahead of the 2012 season we were tracking 10 potentially reproductive females, consisting of a spread of year 2 and year 3 translocates. Ultimately we confirmed natal dens for each one of these animals.

There is also a slight possibility that some of the 4 females we caught in the fall of 2012 and deemed to have been born that spring were actually born in 2011 and would therefore be able to reproduce this year. So, although we think this unlikely we will have to keep a close eye on what these animals are doing to be sure we don’t miss anything.

Doubtless you will see more from us as we start confirming dens and setting remote cameras. Over the first 3 years we have seen the den season really start to kickoff in late March with our median date of den confirmation (this date can sometimes be a day or 2 later than the kits actual date of birth) being March 30th. The majority of dens are generally found within a week or so around this date although our data shows a spread of about a month for the population as a whole. Our earliest record thus far is March 17th, only 1 week away!

Here is something you’ve seen before to whet your appetites.

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Hopefully new pictures will follow in the next month!

-CAB-

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All About The Numbers

How many are there? That may be the most asked question in the history of ecology and wildlife management (at least one of them). Unfortunately, it is not an easy question to answer with any certainty. Animals don’t line up and volunteer to be counted, and thus biologists must find ways to estimate population sizes rather than having absolute and verifiable counts. Many hours of research (link) and multiple volumes (link) have gone into designing and describing ways of estimating populations sizes, and there are still many unsolved problems that are being worked on all the time.

Estimating population size for animals like fishers is difficult because they are relatively rare and spread over large areas that may be difficult to access and survey. Trapping is one method that we can use to make estimates of fisher population sizes using mark-recapture techniques. Additionally, trapping gives us insight into the sexes and ages of the animals what we capture. Because we attempt to survey as much of the area where fishers might live as we can it requires a lot of traps spread out over a big area (see the map below). It’s a busy time and a bit frenzied (hence “Fisher Frenzy”).

Map showing distribution of traps that captured (red dots) and did not capture (blue dots) captures during fall of 2012

Map showing distribution of traps that captured (red dots) and did not capture (blue dots) fishers during fall of 2012

Kevin gave some basic counts of the animals we captured but I thought I would provide a little more detail about the trapping, and some of the implications of the results. Of the 29 fishers we captured 14 were males and 15 were females. The majority of animals we captured were animals that were born on Stirling and that we estimate at 6-19 months old. You can see the percent of animals that we captured from each cohort in the top panel of the figure below. Though we captured more young animals there are still substantial number of adult animals from each of the first 3 years of the translocation. To date, we can confirm that 11 translocated fishers have died, and a minimum of 23 animals were born on Stirling – a net gain of 12. Unfortunately  we do not know the fates of 14 translocated fishers (lost collars etc) meaning that some, or all, could have died. Still, the number of  young fishers we’ve captured is nearly the same as all translocated animals that died or have gone missing.

Percent of fishers captured (top panel) and percent of the known alive population (bottom) by their release or capture cohort

Percent of fishers captured (top panel) and percent of the known alive population (bottom) by their release or capture cohort. Juv 2011 and 2012 are those animals less then 2 years old born on Stirling and capture in those respective years. AdY1, AdY2, and AdY3 are adult animals released onto Stirling in Year 1, Year 2, and Year 3 of the translocation

Another point to consider is that we know we do not capture all fishers in our efforts. In fact, because we radio-track animals, we know of at least 6 fishers that were alive and on the study area that we did not capture. Though we capture a relatively high percentage of the animals that are on our study site, we know we do not get them all – adults or juveniles. Thus, it is very likely there are more young fishers out there than we can document. I have included a secondary figure (bottom panel) that shows the percent of animals in each cohort, and by sex, relative to all animals we can document (captured or otherwise).

So there is still uncertainty to the question of how many fishers exist in the northern Sierra. At a minimum we know that 38 fishers were alive at the beginning of our trapping (those captured + those not captured but known through telemetry). This is 2 fewer than the 40 total we released. Preliminary mark-recapture analyses gives a population estimate of 29-45 fishers, and this seems to make sense given our other information. For now, fishers seem to be doing well enough to survive and reproduce. The spring of 2013 is the first year that we will be tracking female fishers, born on Stirling, that will be able to den. Meaning, next fall is the first year we can capture the progeny of fishers born in the northern Sierra Nevada.Documenting this will be another important milestone and indication of how the population might fair in the future.  Hopefully, we’ll see you all next fall for the Fisher Frenzy.

-ANF-

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Fisher Frenzy

Fall brings about a good time to try and trap fishers, and we have been very busy over the past month doing just that.  This intensive trapping effort of the Stirling district, dubbed “Fisher Frenzy”, finally concluded this past week.  The trapping that we conduct here serves many purposes (some of which will be discussed in future posts).  Importantly, it allows us to examine the condition of both juveniles and adults, and affix radio-collars on selected fishers so we can track them in the future.  This year, we split the trapping effort between two different sides of the study area, running the first 14 nights of trapping on the eastern portion of the study area, and the last 14 nights on the western side.  When we talk about different sides of the study area, we are using the north-south running Butte Creek as the divider.  This split has more to do with logistics than actual geography.  The sides are accessed from different highways (and getting across the creek is time consuming).

The beginning of this years’ event coincided with the first major storm of the fall, which soaked the lower elevations and left 1-2 feet of snow up in the higher areas of the study area.  This made for a challenging couple of days, and closed many of the traps temporarily.  Luckily, a dry spell followed which allowed us to get nearly everything re-opened, and over the two week period we were successful in capturing quite a number of animals.

On the east side, 16 individual fishers were trapped.  We captured a good mix of both adults and juveniles, males and females.  Total number of fisher captures on this side was 26, with a few animals being trapped more than once.  In addition to the fishers, we caught a variety of other mesocarnivores in the traps.

After the first two weeks we left our comfortable accommodations (the former SPI office in Stirling City) to camp out on western side of the study area.  Again we got a fair amount of rain and a bit of snow, but caught a good number of fishers on this side as well.  Over the final 14 days, we were able to capture 13 individual fishers (17 total).

In addition to only looking at fishers, this year some of the folks from the CDFG Wildlife Investigation Lab and the Integral Ecology Research Center came out to do examinations of some of the other animals that we catch.  Spotted skunks, ringtails, and grey foxes were processed, with the general purpose to look at disease exposure in fishers and these other forest mesocarnivores.

Overall, we are pretty pleased with the way things went.  Between both sides, we caught a total of 29 individual fishers during 28 days.  We know that we failed to capture a few animals (those with collars which are still working), but that is expected.  Some of the animals are in areas that were hard to get to (especially after the first snow), and some seem to just be very trap shy.  Now we have the task of keeping track of all these new animals, and it will be interesting to find out where some of these younger animals will end up living.

Over the entire month, we ran somewhere in the neighborhood of 2500 trap nights.  This was a massive effort that could not have been done without the help of many people.  Specifically, we got some much needed labor from Sierra Pacific Industries, as well as the use of the old Stirling City office so we didn’t have to completely rough it for a month.  US Fish and Wildlife provided many helping hands, as well as a life-saving wall tent and stove in the latter parts of trapping.  Among many other things, Fish and Game provided the mobile lab which made processing fishers less stressful than working them up out in the field. A huge thank you to everyone who came out to lend a hand!

Here are some pictures of the event.  Enjoy!

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