From: "Clive A Marks" 
> I'm a wildlife biologist in Victoria (Australia) interested in the
> behaviour of large burrowing mammals.  Is it worth investigating the
> ability of geophones to detect burrowing sounds and animal movement
> within burrows if they are placed in close proximity?  Any advice would
> be appreciated!

Dear Clive Marks,

      Can you outline just what sort of measurements, activities, animal 
species, size, distance, etc. you want to record / use? Your EMail was really 
too vague to give definitive answers. Most small animals tend to move rather 
quietly unless they are actually running. Piezo disks are good at picking up 
ground vibrations up to several hundred Hz, which might be made by actual 
burrowing. They are both cheap and very sensitive. I have used a stereo pair 
for locating water leaks. Commercial water leak detectors and geophones tend 
to be expensive. Second-hand geophones may be quite reasonably priced - see 
www.ebay.com. The ~10 Hz ones should be OK for your task. There is an 
amplifier circuit on the PSN site. Geospace geophone characteristics are now 
at  http://www.geospacelp.com/ There is an article on geophones at 
http://www.tenrats.org/geo.shtml and on Walts geophone site at 
http://www.pacificnet.net/~dfheli/geophon.html  

       Other sensors that you might wish to consider are Infra Red emitter / 
detectors, which could be either placed across a hole / track, or retro 
reflective types to sense close approach. Quite high sensitivities can be 
archived using pulse signals and coherent detection. Commercial IR intruder 
beam sensors are available. Ultrasonic detectors working in the 40 KHz range 
will also detect animals and can be used to measure velocity. Small animals, 
some birds, bats and insects may be able to sense these signals. 
Electrostatic detectors can be of the type which react to static charges or 
to RF capacity changes. 10 GHz Radio Intruder Detectors modules are 
available, as are pyroelectric heat detector modules. Radio signals may 
penetrate sandy soil quite well. None of these techniques need be very 
expensive, but it is a great help if you have the services of someone really 
competent in electronics.

       You can also use the small surveillance CCD cameras with Infra Red 
illumination to monitor animal movements. The modules are fairly reasonably 
priced. If you are using a CRT monitor to observe movements, you can use a 
lens and a CdS photocell + amplifier to give an alarm or to switch on a video 
recorder. Pyroelectric detector modules are also successful for this. I have 
used them to detect animals at close range, from field mice upwards in size.

      You need to consider how you are going to separate the signals you want 
from noise (wind, rain, vehicles, ground movement) or interfering signals 
(other animals) as well as how seriously your equipment will encroach on the 
environment or alter the behaviour of the animals that you wish to observe.

      I hope that these suggestions may be of some help. I would appreciate a 
brief EMail in reply, please.

      Regards,

      Chris Chapman
From: "Clive A Marks" 

> I'm a wildlife biologist in Victoria (Australia) interested in the

> behaviour of large burrowing mammals.  Is it worth investigating the

> ability of geophones to detect burrowing sounds and animal movement

> within burrows if they are placed in close proximity?  Any advice would

> be appreciated!



Dear Clive Marks,



      Can you outline just what sort of measurements, activities, animal 

species, size, distance, etc. you want to record / use? Your EMail was really 

too vague to give definitive answers. Most small animals tend to move rather 

quietly unless they are actually running. Piezo disks are good at picking up 

ground vibrations up to several hundred Hz, which might be made by actual 

burrowing. They are both cheap and very sensitive. I have used a stereo pair 

for locating water leaks. Commercial water leak detectors and geophones tend 

to be expensive. Second-hand geophones may be quite reasonably priced - see 

www.ebay.com. The ~10 Hz ones should be OK for your task. There is an 

amplifier circuit on the PSN site. Geospace geophone characteristics are now 

at  http://www.geospacelp.com/ There is an article on geophones at 

http://www.tenrats.org/geo.shtml and on Walts geophone site at 

http://www.pacificnet.net/~dfheli/geophon.html  



       Other sensors that you might wish to consider are Infra Red emitter / 

detectors, which could be either placed across a hole / track, or retro 

reflective types to sense close approach. Quite high sensitivities can be 

archived using pulse signals and coherent detection. Commercial IR intruder 

beam sensors are available. Ultrasonic detectors working in the 40 KHz range 

will also detect animals and can be used to measure velocity. Small animals, 

some birds, bats and insects may be able to sense these signals. 

Electrostatic detectors can be of the type which react to static charges or 

to RF capacity changes. 10 GHz Radio Intruder Detectors modules are 

available, as are pyroelectric heat detector modules. Radio signals may 

penetrate sandy soil quite well. None of these techniques need be very 

expensive, but it is a great help if you have the services of someone really 

competent in electronics.



       You can also use the small surveillance CCD cameras with Infra Red 

illumination to monitor animal movements. The modules are fairly reasonably 

priced. If you are using a CRT monitor to observe movements, you can use a 

lens and a CdS photocell + amplifier to give an alarm or to switch on a video 

recorder. Pyroelectric detector modules are also successful for this. I have 

used them to detect animals at close range, from field mice upwards in size.



      You need to consider how you are going to separate the signals you want 

from noise (wind, rain, vehicles, ground movement) or interfering signals 

(other animals) as well as how seriously your equipment will encroach on the 

environment or alter the behaviour of the animals that you wish to observe.



      I hope that these suggestions may be of some help. I would appreciate a 

brief EMail in reply, please.



      Regards,



      Chris Chapman