From: Syd Curtis <>
>
>
> On May 14, Walter wrote:
>
>
>>> From: Walter Knapp <>
>
>
>>> Subject: Re: [Nature Recordists] Guideline suggestions
>>>
>>> There should be accurate location information with the sample. Ideally,
>>> all samples would be submitted with a GPS reading. That may not be
>>> practical as there could still be people without GPS, ...
>
>
> Is there a GPS instrument that will give a reading in a deep valley in a
> mountainous area from beneath the continuous closed canopy of a rainforest,
> 100 feet or so above one's head?
>
> That's the sort of situation I find myself in while studying lyrebirds. I'd
> get such an instrument if it exists, but I fear that topography and canopy
> preclude getting the necessary signals at ground level.
Topography would not be a severe problem, but very thick vegetation will
still make it hard to get a reading. Modern GPS are much better at it
than earlier models. I'm sure the military has GPS that cope in such
situations. There are also GPS that are sold for survey or research
locating that are very capable, much more sensitive than standard
consumer GPS. I just use ordinary consumer GPS and have little problem.
And I have gotten signal in such situations.
This is often cited as a reason for ruling out GPS, it's not. Even if
you can only get a occasional reading and have to extrapolate on maps,
the location data will be much more reliable. In the case of a Lyrebird
site, which is fixed for long periods, going to the trouble to
accurately describe the location is worth it.
I get GPS readings with my current GPS in thick cypress swamps or
bottomland woods. On rare occasion it will loose signal, but that's
uncommon. It's triangulating from a dozen or more satellites scattered
across the sky, but can do it with somewhat reduced accuracy from two or
three if that's all that come through the trees or can be seen from the
valley. I've used this particular GPS for navigation all across the US
and even into canada in all kinds of terrain and forests. Typically it's
estimating it's accuracy at 15-20'. And that's without using it's
special averaging features to improve accuracy. Since Clinton ordered
the military to quit messing it up GPS accuracy has improved. Used to be
I'd only know within 40-50'.
> Likewise there's a lack of mobile phone contact in most of my lyrebird
> areas, and I wonder (from the depths of my technological ignorance) whether
> it would be possible to get phone contact by erecting an aerial and
> connecting it to a phone - as one used to do to get an AM radio signal in a
> remote area half a century ago. A catapult and line could be used to haul
> an aerial well up towards the canopy.
This is how you would probably have to use a GPS in thick rainforest, at
least some of the time with consumer gear. The antennas are available on
a separate long lead.
For rainforest work you would do well to investigate the research grade
gear. Unfortunately, that stuff is very expensive. And also usually bulky.
Best bet is to see if you can borrow a modern GPS and see how it does.
Satellite cell phones would be able to reach the locations, but would be
in the same boat as GPS. I've not heard of really long lead antennas for
them. And, again, it's expensive to run that type of cell phone.
Any modern scientific study should be describing locations with the same
accuracy as a GPS preferably landmark independent. It is not a
requirement that you get that accurate data from a GPS. It's ok to use a
old style survey team, or failing that the best reading you can get from
a topo. The important thing is to describe the location accurately so it
can be found again even if all the landmarks change. GPS just happens to
be far and away the best way to do this reliably and consistently.
I've read a great many location descriptions from the pre GPS days and
then tried to find the place. It can take a lot of time to find, or even
be impossible. But every time I've had a GPS location it's been easy.
Several of us are working on one of those old descriptions right now, a
site that has a unofficial report of having Pine Barrens Treefrogs in
Georgia. Reported by a person who is dead, a description found in some
old papers. Uses place names that are no longer used, in fact to which
we have found no reference, the description still leaves us with many
square miles to try and search. All this for what we believe was a hoax,
has to be checked anyway. I'll be burning expensive gas and lots of time
on this. And that's only one of quite a few old locations that are in
need of verification. Try the one who's only location description is
"around Atlanta", with not even a county given. That may be extreme, but
the majority of location descriptions I've worked with have been barely
better. And that includes a lot that referenced topos.
Walt
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