Posts Tagged With: mesocarnivore

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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Life and Death

One of the main things that drew me to fishers was their reputation as a predator. As I mentioned in my last post, fishers are flexible in what they eat and they are extremely skilled at capturing a wide variety of food types. When a fisher kills a squirrel or a woodrat I find it exciting because I know that fisher has helped itself survive for just a little while longer. Yet, fishers are not the only predator out in the woods, and in fact they themselves become the victims of predation (as many of you know).

Research on fishers throughout the western U.S. (including ours) is demonstrating that predators have a significant impact on fishers.  In conjunction with our collaborators (IERC and WILwe can suggest that as much as 60% of our documented mortalities are caused by predation. Interestingly, most of the mortalities we observe occur during the period when animals are actively seeking mates (March – May) or subsequent to the birth of kits when females are actively lactating (April – August).

Distribution of deaths across months for all fishers found dead

It makes sense that animals are susceptible to predation during this period because of the frequency with which they forage as well the energetic demands they may be under. In fact, many studies demonstrate animals foraging in risker ways, or places, under a variety of circumstances (one example).Predators may kill fishers simply to remove potential competition and then simply leave the fisher remains uneaten. Other times they may actually consume the  fisher leaving only a few remains.

1F111 found dead

Females and kits are also vulnerable at the den sites as predators such as bobcat (Lynx rufus) often find and climb the den tree.  Thus, females are exposed to danger at the den site and while foraging.

Fishers apparently straddle a very fine line between being the hunter and becoming hunted. At present we are still trying to understand the relationships between fisher biology, habitat, and predators that explain the why fishers are more prone do becoming prey for another animal during different times and places.

Bobcat at 20058 den tree

The few remains of females 182F4

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Snow Tracking

Last night a small storm dropped a few inches of snow in parts of the study area, and this morning I came across a fresh set of fisher tracks.  This winter’s mild weather hasn’t provided many good snow-tracking opportunities, so I decided to spend some time back-tracking this animal.

I really enjoy snow-tracking, as it allows you to see exactly what habitat an animal is using, how they are moving through the forest, and sometimes affords the opportunity to witness behaviors that are otherwise difficult to see (such as kill sites).  These tracks were in the area occupied by fisher 21392, a female born on Stirling and captured last October.  Though I am not able to confirm that the tracks belonged to her, they appeared to be heading down a drainage towards where I located her (via telemetry) today.

I thought I would share my GPS track-log from today.  In it I listed a few points along the way that were interesting to me.  The overall distance tracked was a little shy of two miles.  Not a huge distance by any means, but still very tiring because of the constant going in and out of drainages and the dense understory vegetation.

Kevin

Track Pattern

Track Close-up

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Return to the field

We seem to be having a spell of good weather over the district currently which is allowing a little more freedom in the field since our return from the West Coast Fisher Symposium in Sacramento. There is still a little snow on the roads at higher elevations and the peaks of Lassen to the North are finally showing white but skies are clear and most of our access points are open.

Yesterday saw an overdue visit to some of our more Northerly females on the edge of the Ishi Wilderness, we currently know of two females in this area, both of whom were located yesterday.

Today I managed the first walk-in on our most recently collared female (see post January 25th 2012). I found her in a draw high above Big Chico Creek keeping an eye on me from the canopy of a large Douglas Fir. The photo fails to do her justice but you can make her out peering down from a mass of branches some 100 feet from the ground.

This being the first time we’ve had contact with her since she was collared I was pleased to note that she didn’t appear agitated, neither vocalizing nor attempting to move off while I was observing her.

-CAB-

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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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Springing the trap

Though the aim of our trapping efforts is to catch fishers, we sometimes find non-target species in the traps.  Striped and spotted skunks, ringtails, grey fox, and squirrels are the usual suspects.  Some of them even seem to find the wooden cubby of the trap comfortable!  Last time I caught a ringtail, I opened the back door of the trap and left to do other work.  Upon returning 4 hours later, it was still resting in the box!

Kevin

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Creatures of the night

With the belated and thus far underwhelming winter storms making an appearance recently a few of us have found ourselves with time on our hands away from the field. In light of this situation the ever industrious Aaron has, among other assignments, set us to work organizing a digitalized mountain of trail camera pictures.

As a (more?) naïve youth I used to quite enjoy going through these pictures, then I came to work in bear country…needless to say, the novelty has worn a little thin. For the uninitiated; it is a favorite pastime of black bears to find, wander around in front of and then try to eat trail cameras, this can become a little tedious to watch the 10th or 100th time you see it. Nonetheless, we do get to see some of the more reclusive local residents going about their business too.

I thought I’d share a few recent favorites to add a little color…then I realized they were all night shots.

Enjoy!

-CAB-

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New juvenile fisher

Today we captured a new juvenile fisher near Hwy 32! This is the 5th juvenile female fisher captured this year (2011-2012), and the 9th total juvenile. She was collared with a VHF transmitter and we will begin tracking her as much as possible in the near future. This is exciting news because thus far 6 fishers have been documented to have died on our project. Capturing 9 juveniles that are independent of their mother’s and surviving indicates that at the least we have replaced those deaths with fishers born on the study site. This is one indication that the populations may be stable or even growing.

Currently we are tracking 24 animals with VHF transmitters and another 9 with Argos satellite (PTT) transmitters. Capturing, collaring and following many animals is important to improve our understanding of what habitat requirements they have and how that is influencing our incipient population.

-ANF-

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Winter wonder land

The first major winter storm we’ve had since November is upon us. So far we’ve gotten a few inches of snow at the lower elevations of the study site, but maybe quite a bit more up high. This makes the roads and conditions difficult and so not many telemetry points being taken right now. it does allow us to work on data entry and analysis a bit more, and with the upcoming meeting of the The Wildlife Society it is not a bad thing. A positive aspect is that we can do some snow tracking of fishers when the weather is bit nicer. It is always fun to follow fishers for a while.

-ANF-

It can get deep quickly

FIsher tracks in the snow

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