Ominous Signals

The other day Aaron wrote about male 18308, who recently died.  I had the task to go out and locate the collar, so I thought I would expand upon what he wrote and discuss the search process.  I have added a couple of pictures of the remains at the end, and though I don’t think they are particularly gruesome, fair warning.

When we get a mortality signal (VHF), or consecutive days of locations in the same spot (Argos), we know it’s not good.  It’s likely that either the collar has fell off, or the animal has died.  I have been fortunate that in the last year and a half of helping out on this project I’ve only had to search for one other collar.  In that instance it appeared that the animal had simply slipped her collar.

Because Argos collars send us daily locations, I was unaccustomed to searching for them.   I quickly realized that searching for one is a lesson in patience and can be very frustrating.  Our VHF collars that we follow on a daily basis give off a signal at around 60 beeps per minute.  The Argos collars, on the other hand, only give off one signal per minute.  Determining what direction the signal is strongest, which would take seconds with a VHF receiver, takes at least 4 minutes with an Argos receiver.  Instead of a simple beep which we get from a VHF, the Argos reads out a number from 0-239 (239 being the closest).

The saving grace in this search was that I had a couple of points from which to start my search, and these were likely no more than 400m from the actual collar.  I started slowly, heading one direction for a few minutes, and then turning around when the strongest signals reversed.  After an hour of searching, I had ended up back at the truck.  Frustrated as this point I headed off in the opposite direction that I had been going, and after another 45 minutes of searching, finally found the collar (40m from where I parked).

As you know if you read Aaron’s post, this wasn’t a happy ending.  I found the collar, along with very few remains.  In situations like this we try to treat the site like a crime scene, and see if there are any obvious clues to the cause of death.  In this instance I wasn’t able to find much of anything, certainly not anything conclusive.  The location was close to a public road (dirt road but traveled fairly regularly), so perhaps he was hit and then scavenged.  Or possibly he was simply taken by a larger predator (i.e lion).  We sent off the remains to be tested for DNA of possible predators, so hopefully they can give us a bit more insight to the possible cause of death.

Obviously a tough day.  This was the first fisher (and second also) I helped to trap and conduct the physical examination.   It was an awe-inspiring experience to actually see one of these animals up close, and left me with a new-found respect for them.


What was left of the jaws.

Argos collar.

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