Tuesday, May 10, 2011

Up and About for Spring

You may remember that I posted some information on the box turtle radio telemetry project that I have ongoing (see The Turtle In the Box, posted on February 23, 2011).  We've been monitoring the critters since late February, hoping to nail down their emergence from hibernation.

Since that time, the six turtles* with radio transmitters attached to their shells had remained buried in their winter hiding locations....until about late April.

On April 20th, the one individual (a male named H001) had left his burrow for the first time this spring.  I found him about 8 ft away from the burrow sitting in a sunny patch.  None of the other turtles had moved from their overwintering locations at this time, although two individuals had "semi-emerged" from winter dormancy.  They (both males) were completely buried the week before, but on the 20th they had come close enough to the surface that their heads and upper shells were exposed. 

Above: H005 found on 5/6/2001 in a burrow created when the root of an old tree stump rotted away.

The rest of the turtles were still down at that time.

By April 30th, all of the turtles had left their winter abodes and moved some distance.  In fact, at that time I couldn't find H001 with the telemetry equipment.  I kept getting a signal, but it was wonky because he had moved so far.  I was in alittle bit of a rush on that particular day, so I had to give up on locating him for the short term.

Above: Undergraduate researcher tracking box turtles with telemetry equipment.

On Friday (May 6, 2011), with the help of some undergraduate researchers, I was finally able to get out and make a full-scale attempt to locate H001.  It took a while, but this time he was found.  Telemetry signals bounce around something terrible when in a woodland (the signal is blocked by and bounces off of trees, rocks etc.).  This is exacerbated if the person holding the telemtry antennae is in a ravine and the turtle being tracked is at the top of an adjacent hill (which is exactly what happened with H001).  The result is that the person who is tracking the turtle may wander around in circles, as the signal leads him/her in many different directions that don't end up at the turtle.  Once I got it through my thick noggin' that this was the score for H001, I finally thought to hike to the top of the ravine slope.  That's when I found him.

There he sat....partially covered with leaves in the middle of the woods.  He looked almost indignant, or at least annoyed, when I walked up to him.  This is probably because no matter how far he travels, this silly pink bipedal mammal seems to find him.

I'd be annoyed too.

Above: the incredibly mobile H001 as I found him on 5/6/2011

Above: Box turtles blend in particularly well.  Pictured above is the same turtle (H001).  This photo was taken at chest height, pointed down at the turtle.  He's in there, if you know where to look!

Anyways, he really had to high-tail it to get that far in such a short time.  In the process, he crossed a rather quick flowing stream with pretty steep banks and a rocky bottom.  How he crossed the stream, I honestly do not know.

Why did he go so far?  It's likely part of what he does every year.  Perhaps he was on the hunt for a female...males tend to move alot for this reason.  In general, however, this is not a very mobile critter.  Most remain within the same small home range (i.e., the area the animal roams in during the active season) throughout their lives.  For example, an individual Eastern Box Turtle tracked in New York was found to remain in the same general home range for 15 years (Nichols, 1939).

We'll see where he goes from here.

Literature Cited:

Nichols, J.T. 1939. Range and homing of individual box turtles. Copeia 1939: 125-127.

*At the start of this study, 9 turtles were affixed with radio transmitters...three had the transmitters chewed off by something over the winter.  Although it's plausible that they were eaten by a racoon or oppossum, I never found any turtle corpse....just the transmitter.  I'm hoping the Raccoon, or whatever, simply chewed the transmitter off, but realized the actual turtle, with its tough shell, was too much work and gave up.

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