Posts Tagged With: denning

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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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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Categories: Field Day, Updates | Tags: , , , , , , , , , , , , | 1 Comment

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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