Hi Courtney,

One challenge for auto-detaching tags on seals is kind of logistical/financial rather than technical.  A floating tag requires a vessel to go retrieve it, and since seals may venture pretty far out to sea, it might require a pretty substantial vessel. Many seal projects I've worked with don't even have boats as a regular part of their work, so this could require a significant increase in operational costs and/or efforts. Not impossible of course, just a consideration. 

Wildlife Computers has a remote-controlled release mount for seals, which would allow you to wait until they're on shore to drop it off, obviating the need for a boat.  This still does leave some material behind. Making a predictable/controllable release mechanism that wouldn't leave something behind is quite a challenge for seals, where epoxy to the fur seems to be the most reliable attachment method.

Hello @CourtneyShuert 

If I am not mistaken, Wildlife Computers was developing or has developed a remote release package for such an application as has a much smaller company, Desert Star Systems. I do not know where either company stands in terms of functionality, but I think for both cases the animal still has to carry some kind of an attachment plate that will eventually be shed off. In theory (purely theory) and assuming a product exists, you/they could consider adapting the material of the plate to something that is 'sustainable' and not plastic or similar.

(edit: I noticed Kyler linked the WC product above)

I have couple of good use cases for this model in a conservation project here in Cambodia however limited by lack of funding.  Would be happy chat if you are interested. 

My study in particular is only looking at species that go under fence holes in Southern Africa. The hole determines species size and juveniles for these species are so small the collar would just fall off. I think a proper study could really determine these collars could be useful if the right study species and setting location was determined. 

Congratulations, very exciting! Keep us updated!

This is so cool @Mauricio_Akmentins - congrats and look forward to seeing your project evolve!

Hi Brandon,

This is hard for me to write, because I don't have good news for you.  You can find many receivers and transmitters for 433MHz that are used for remote control, such as wireless doorbells, garage door openers, lost model locators, etc.  These are extremely cheap, a couple of dollars literally.  While this tech can be modified to operate with wildlife tags (around 150MHz), we are talking about hacking RF, not to be approached lightly.

If you really need to DIY, I see 2 options: migrate to 433MHz and build/rebuild all your kit (tags, collars, receivers, locators).  Commercial solutions are cheap and available, the work remaining is not much above handyman level.  But it is work, and not just work but also testing.

The other option is to remain with 150MHz (although you can make your own tags) and modify an aviation receiver (it lets you listen in to aircraft talking to each other or to the airport).  These receivers operate at 130MHz, which puts it in spitting range of 150MHz wildlife tags (this matters).  This is the option I'd go for, just because I know it can be done, and I have less sense than curiosity.

You mention you're working with an engineer, here are a couple of pointers:

• with an SDR (the "digital USB receivers" you mention) you can scan some bandwidth to detect radio pulses. I'm only familiar with the Lotek coded VHF transmitters but they can be received as in the Motus Sensorgnomes. I can point you at the code used there, it does involve a good amount of digital signal filtering/analysis code. One issue with the SDRs is that they're pretty power hungry so you need to plan on more solar panel and battery than you may like, e.g. even rPi Zero + SDR is probably >300mA. Another issue can be interference in that SDRs have a very wideband front-end and so TV, radio, and other stuff can desensitize the front-end.
• there are integrated receivers (ICs) that can be tuned to 150Mhz and can detect VHF transmissions, it's easy for non-coded ones, a bit more involved for coded ones. Specifically, the Semtech sx1231 or sx1276 series are widely available (often called Hope RF69 or RF96, which are modules with those chips). You need someone comfortable writing a customized driver that uses OOK mode or RSSI detection. The other issue is that while there are many suitable boards available for 433/868/915Mhz (e.g. Adafruit, Sparkfun, LilyGo, and many others) you most likely won't find one for 150Mhz. However, for RX-only the matching isn't so super important if you have a good antenna and the signal isn't crazy weak. From a power point of view these can sip power so you can run one on an 18650 for days and a small 1W-5W solar panel is most likely all you need.

Hope this helps...

Hi Peter, we manufacture solar powered Iridium trackers for birds, crocs/alligators and collars for various species. Our longest standing unit is a 55g unit on a Vulture and has been going for 4 years, providing data on an hourly basis. Our croc units include a pressure/depth sensor and provide details of depth and time at depth. Most of our devices include a VHF transmitter which is fully configurable over the air (you can change frequency, pulse duration, pulse interval and operation times - good for security).

Hello Peter, 

Have you find a solution ? I will be happy to discuss with you about your project and field challenges ? 

Best,

Virginie

I would look into the TNFD (Taskforce on Nature-Related Disclosures), Finance for Biodiversity, Accounting for Nature, etc. which are all focusing on how to incorporate nature risk into corporate reporting and sustainability frameworks!