Love is in the Air

Okay, so maybe love isn’t the best choice of words.

The other day I was searching for the natal den of one of our trans-located females.  Having narrowed the signal down, I thought I knew where I needed to go in order to find her.  As I was riding on the ATV past an old road, I caught a “fisher log” out of the corner of my eye.  Now I often see fisher shaped rocks and logs, and 99 times out of 100 they are just that.  This time however, as I backed up to get another look, this particular log turned around and loped off!

I quickly grabbed my gear and started walking after the fisher, thinking it was probably the female I was looking for.  As I walked a ways down the road I realized that although I was extremely close to the female, her signal indicated that she was not moving.  Just then, one of the Argos collared males appeared and started to approach me!  He got about 15 feet away, then moved up-slope towards a large tanoak.  After sniffing around the base of the tree for a few seconds he slowly walked off.  Not surprisingly, this turned out to be the tree the female was in!  This was the first time I have personally spotted a male at a den (although it isn’t too uncommon among the field crew, and our cameras detect it frequently).  It was certainly nice of him to lead me to the tree she was in.

The spring denning time coincides with the breeding season for fishers.  For us on the ground, it is probably one of the best opportunities to spot the males out in the woods.  Males are busy seeking out the females, and just like in this case, often end up at their dens.  I put up a camera pointing at the tree, and it caught a cool series of pictures.

The male in the picture is not the male that led me to the den.  He is un-collared, and appears to be quite a bit smaller than the one I saw there.  It wouldn’t surprise me to catch some larger males visiting the den in the next few days.  This particular female has been in the same tree for a few days now, indicating this this is probably her den.  We are starting to see many of the females we are tracking settling into denning behavior, but more on this in a few days!

 

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.

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.

Hopefully new pictures will follow in the next month!

-CAB-

In The Field With Fishers

Our situation on the ground has been a little hectic over recent months and some of you avid followers may have been feeling a little neglected when it comes to field updates. Well, fear ye no more, I shall share a few details regarding the animals we are currently tracking on and around Stirling as of late February.

We are currently tracking 23 Fishers with active telemetry transmitters on and around the Stirling District. Of these, 16 are fitted with VHF transmitters that we must actively track. 15 of these animals are females wearing VHF collars, the other is a male born on Stirling in 2012 who was given an implanted transmitter due to his age and potential to outgrow a collar. The remaining 7 animals are males of greater than 1 year of age fitted with ARGOS collars, these collars collect locations via satellite and can be conveniently tracked from the comfort of our desks. A breakdown of these animals by year of birth/translocation can be seen in the table below.

Right now we are unable to account for 3 more animals (2 females, 1 male) with potentially active transmitters who we hope are still going about their business out there. They were all born on Stirling in 2012 and have been missing for over a month. Sometimes such animals turn up in unexpected places (see previous post “The Grass Is Always Greener”) or are recovered during our trapping efforts and sometimes we never learn their ultimate fates. Either way, they are young and wild and all we can do is to keep searching.

You can get an idea of the spread of our animals across the study area at the moment from the aerial photos below, to give a little perspective the lines on the image represent the county lines of Plumas to the East, Tehama to the west and Butte in the South.

Female locations:

Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

Male locations:

Year 1 translocates in Purple, Year 2 translocates in Yellow, Year 3 translocates in Blue, Juveniles from 2011 in Red, Juveniles from 2012 in Green

As you can see we have a pretty wide spread of animals across our study area at the moment, and we are aware of uncollared individuals in many of the intervening areas. As denning season creeps up on us we will be kept busy trying to keep tabs on everyone, this year is shaping up to be an interesting one with more potential dens than any previous year, I will update you all with some of our denning predictions in the near future.

-CAB-