Monthly Archives: November 2014

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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Getting the Point

Getting the Point            

October is long gone and the shortening days of November signal that fall trapping is coming to a close. Unfortunately, we have not been able to update all of you with the happenings as much as we’d like, but I suspect we’ll be putting out more posts in the coming weeks.

One of the parts of trapping, and handling fishers, that I most anticipate is in the moments after we’ve sedated a fisher and get to physically examine it for the first time. One of the first priorities is to  see if it has any major wounds or ailments that need immediate attention or that give us concern. Recently, while examining a female fisher (captured on Stirling in the fall of 2012) we noticed that there was something odd about the area around her right shoulder and neck. Not coincidentally Roger and Kevin both spotted the same thing when I did and all three of us were looking on at several very large, stiff, and prominent hairs jutting from the fisher. I found myself thinking ‘those don’t look like fisher hairs, and I wonder what they are?”. Kevin and Roger were apparently thinking the same thing and nearly in unison we shouted “PORCUPINE!”. A little further examination confirmed our suspicions. Three porcupine quills were embedded in the young female’s right shoulder suggesting she had an encounter with porcupine in the not too distant past.

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Close up of 3 porcupine quills in right shoulder of female fisher captured on Stirling in 2014

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Female fisher with porcupine quills in right shoulder

Perhaps you are wondering why such a fuss about a few porcupines quills? Well, there are a few reasons that this got us excited, but mainly it was because we have never found a fisher on Stirling with porcupine quills. The discovery is significant because fishers are one of the few consistent predators on the spike-laden rodents when they occur together. As  you probably know, or can deduce, porcupines have all those spikes as more than just a bold fashion statement – they offer pretty good protection from most predators (view a recent video of an African porcupine vs lions). Fishers are uniquely adapted to capture and kill porcupines and they may have an important role in regulating porcupine populations in some areas. Porcupines are large relative to other prey fishers catch and kill (e.g., squirrels and hares) and they provide a large source of energy to fishers (read this if you want to learn more). We have never documented porcupines on Stirling, since we’ve released fishers, and this suggests that porcupines are rare. Having porcupines and fishers on Stirling at the same time might alter the dynamics of how and where fishers forage, their home ranges size and structure, and even their population dynamics.

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Porcupine (Erethizon dorsatum)

We don’t know if our female fisher actually killed a porcupine, but she certainly ran across one and we have a pretty good idea of the places she likes to hang out in. For now, it is only a fun little anecdote about one of the fishers on Stirling. Nevertheless, it is an exciting story and perhaps the first in a series of important observations. Such information is one of the reasons we endure a long trapping season and why we subject animals to the burden and stress of capture. Ultimately, it is all important information about what fishers are doing and how their daily lives translate into their ability to persist.

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Depiction of a fisher capturing a porcupine (painted by Consie Powell)

-ANF

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