For those of you not aware, our annual fall trapping effort on Stirling has been underway for several weeks now and we are getting lots of exciting results. Probably the most exciting, at least for me, is that we recently captured a female (ID: F8B8D) that we released in year 1 (2009-2010) of the project. Capturing this important for a number of reasons and I’ll explain those reasons a bit better a little further along. First, I wanted to give a little history on this female to give some context for why her recent capture in important.
Female F8B8D was captured in January of 2010 north of highway 299 and between Shasta and Trinity lakes. We deemed her a good candidate for translocation to Stirling because she appeared to have reproduced in the past and she was in good physical condition suggesting she was mature and good handle the stresses of being hauled off to a new landscape. Like all females in the first year of the translocation she was implanted with a VHF transmitter so that we could track her movements. After she cleared our disease protocols we translocated her to Stirling on January 10th and released her in a tributary of Butte Creek near where most of our year-1 fishers were released. I can tell you she didn’t stay there for very long and the next day I found her on the east side of the ridge in the West Branch of the Feather River. For the next 6 months we often found her on the ridge between these two drainages (see the map of her 2010 home range). Unfortunately, we could never confirm that she had kits, because she never stayed in a den tree for very long. We suspect this may have something to do with the timing of when she was released, but that is another story. In the middle part of the summer F8B8D started moving south towards Stirling city and in fact the final time we found her signal in 2010 she was just to the east of Stirling city. Unfortunately, we were never able to find her signal again and all indications were that the transmitter had failed in early August of 2010.
Since we lost track of F8B8D in 2010 I’ve often wondered about what became of her. Each time we’ve trapped she has been a female that I’ve specifically thought about and tried to places traps in her former home range and in places I thought she might have settled into. We never had any success catching her and frankly we’ve had very poor success trapping any female that we released in that first year. In fact, up until this fall we had only recaptured 1 other female from the year-1 cohort and that was back in the spring of 2011. In truth, I had resigned myself to the idea that those females were all dead or were just of the disposition to never be captured again. Of course, not knowing which of those two possibilities were true was a problem because we it left us without important information.
The recapture of F8B8D helps to answer a few of those questions. Or, at the least it gives us insight into what the truth really is. Most importantly, we know that some (at least one) females that were released in year 1 are still alive. Maybe there are more out there living in places that we released them and hopefully giving birth to new fishers that will help to maintain our young population. Now that F8B8D has been recaptured (twice now actually) and collared we can see what her current home range looks like and how it compares to the areas she was using in 2010. We can also see how other fishers have been responding to her current home range by studying their space-use in relationship to hers even while she went untracked. F8B8D was recaptured not too far from the last place we tracked her and so perhaps she has been living in that same area this entire time. We also learned that the implants that we gave these females can remain in them and have relatively little impact on them. Upon removal the transmitter was still intact and doesn’t appear to have done any internal damage. F8B8D was about the same body mass and condition as when we released her and that suggests that she has been making a reasonable living for herself since we released her. Based on her teat size we also think that F8B8D likely had kits in the past year and this demonstrates that the year-1 females are not only living but also reproducing. Now, it’s possible that this is the only year-1 female still alive, and we just don’t’ know for sure, but it is a positive sign.