Yes - my Master's student Stephanie Symons ([email protected]) has two seasons' experience with this method, using Ecotone GPS tags, please contact her directly.

We tried to  use ecotone on ear-tags with wildebeest,  contact me directly [email protected]

Many thanks, Tony, I have emailed Stephanie.

Many thanks, Mark, I have emailed you.

Hi

I have worked with UHF downloading for GPS-ACC transmitters with vultures in Namibia and Israel.

We have used tag produced by E-OBS, Germany and others in my lab former have been using them for pelicans, storks etc. Overall their products are very recommended, and we were pleased from their reliability, performance and service. They will be my personal first priority company for any future project.

As for data download itself, the range is really sensitive to line of site, and to pointing your hand held antenna in the exact direction of the bird. Note that the orientation of the elements in your handheld antenna (vertical or horizontal) also have a lot of effect on performance, depending on the orientation of the tag during the download, so try it out to find the best angle.

The duration of a single download typically takes a few minutes (say 5-10) with high variation, depending on the technology you use, the communication signal quality (are you near or far) and the amount of data to be downloaded. It is much easier if the bird is static (e.g., in the roost), and not on the wing.

The distance, again may vary but we could easily down load from 1km in fair conditions, and even up to 4 km if we were really lucky, and all stars aligned... The single most important advice I can give you is to use a long antenna. Normally we used a ca 1 m antenna (e.g., http://salestores.com/antene17.html?gclid=CPOc1p2M7M4CFVKIfgodqoUF7g#.V8cIpvkrLRY , not this particular one, this is just an image to illustrate). These are convenient to work with, but when we really wanted to push the extreme download distances (e.g., inaccessible roost sites) we worked with much longer antennas (say 2m long, many elements). They are heavier and cumbersome, but will double your range if you use them appropriately

Good luck

Orr Spiegel  

Thank you very much, Orr, for all this helpful information. I was not aware of E-OBS, will contact them. Also looking forward to reading some of your papers.

Regarding pointing the UHF antenna exactly in the direction of the bird, can you rely on being able to see the tagged vulture from a distance? In our case, the tagged imperial-pigeon will almost certainly not be visible, even when it is present in the nesting/roosting area. (Because they will be among trees with many other birds, all flee if anyone tries to approach closer to see them)

Does your equipment allow you to detect signal strength of the tag?  I mean, can this type of mobile download receiver be used analogous to manual VHF tracking, so the user could hear weaker/stronger 'ping' when the antenna is rotated from poor to good alignment?

Many thanks!

hey

In most cases it is impossible to see the bird from the distance used for downloading, even with binos. the tags we used have  built in pinger (i.e. a 'classical' radio transmitter, in our case at a different frequency range). if your tag doesnt come with a built-in pinger, i highly recommend adding one, this cheap device is essential for finding the bird in the field.

Typically these pingers have much longer range than the data download (up to 10 fold in our case). Using a second antenna, and receiver (i.e., not the base station used for downloading for instance AOR 8200 or Yahesu 500), this pinger allows you to locate the bird from afar, and beacon in to (by foot/car/boat/plane). 

once you feel you are close enough and you get a good directional sense to the bird's estimated location you can point the larger, data download antenna, and start downloading (hopefully). 

as for estimating the signal strength of the data download itself- since you know the frequency used for communication between the GPS-tag and the basestation (often 868 Mhz), you can tune the other receiver to this one and than listen to the communication. a good download sounds like a chain saw, or a driller (i.e a constant rapid kliking, but sweet...). it becomes less stable when downloading is inefficient.

i guess that there are probably many other tricks an tips acquired with field experience, but its hard to write them down, one simply have to be in the field to show them...

cheers

Orr

BIG thank-you Orr. I very much appreciate so much detail from your field experience. Its given me a lot to think about and improve preparation for this project. Thanks so much!

Hi Julia, we have been using UHF download for Vectronic GPS transmitters from late 2010 to early 2015 on griffon vultures in Italy (central Apennines mountain range). As far as I know Vectronic discontinued bird gps production unfortunately. We usually downloaded the data on late afternoon-evening when the birds were roosting on cliffs. We noticed that the download distance could usually be more than twice the distance the manufacturers guarantee and during day-time and from a prominent point we could download huge amount of activity data as well as positions (from flying vultures) up to almost 30 km.

If you have more specific questions let me know!

Hi Mario and thank you. Great to know about your research with griffon vultures. What an  impressive distance for UHF download! I just found Vectronic website and as you say, they no longer offer GPS devices small enough for birds unfortunately.

At our study site, I suspect we could have poor download conditions due to dense small trees.Did you ever try downloading with trees between you and the birds? 

Dense vegetation is claimed for a strong effect on data download success. I never experienced too much dense tree vegetation between me and the tags. Luckily. But it is just a matter of what kind of wildlife you are tracking and their habitat use. You could contact Willem Bouten, Amsterdam University and try to get info from his UVA-Bits GPS loggers. Regards, Mario

I further suggest to take notice of every downloading attempt, recording relevant 'variables', as to keep track of what could play a role influencing downloading success, which could be helpful to modulate future attempts and technical solutions, as well as to understand why the system is working properly (or not). Regards.

Hi Julia,

I have been using e-obs collars on Eurasian lynx in a montane area in Turkey. To my experience if you have severeal high hill tops ascendant to your study area it is very easy to download the data when your animals are in the inactive phase of the day. I could download data many times over more than 5kms away and once even from 16kms from a mountain slope to a hill top directly looking to each other!

I agree with Miha that if the animal is moving during the download, connection breaks very often. So, I always try around 11am to 3pm when the animals are generally inactive and resting on slopes.

As far as I know e-obs is very successful on bird tracking as well.

Cheers,

Deniz

Thank you Miha and thank you Deniz, for sharing your valuable knowledge and experience. Very interesting about long download distance from hills/high location, and better connection when animals are inactive. 

From much helpful input to this question, it seems my study site is *not* well-suited for download - many trees, no hills.

GPS-GSM as Miha mentioned might be an alternative. I need to contact the various suppiers to see if they have devices small and light enough for tape attachment on birds

Thank you Miha. If a GSM message must be sent at the time of recording each GPS location, then indeed it would of very limited value for my birds.

I was thinking GSM option will be similar to UHF download option, in that GPS locations will be stored until the data get downloaded, e.g. when the bird moves into GSM coverage, at that time the previously stored positions could be sent... maybe that is a wrong assumption?

Hi, about solar panels, keep in mind that if individuals of the target bird species use to have quite often rude contacts with conspecifics (like vultures around a carcass) panels can be damaged by their powerful beaks. Some manufacturers, like Uva-Bits, in such cases can provide a more resistant cover for panels. Almost all solar-powered transmitters we deployed on griffon vultures suffered from such a problem. Which has likely decreased the re-charging ability of panels or has caused their complete failure.