Hello, little ghost.
I understand your concern about this, I have the same concerns and I must admit I was a bit scared to ask for help in this because I do not want that people without knowledge about birds do this.
I been working since 15 years ago studying birds with different researchers in different research projects. I work bandding birds and "strapping" them different devices to study his migratory movements. I have been using geolocators, GPS-GSM devices, PTT with Argos system, etc. I know all the permissions I need to capture birds. I know how much weight a specific bird can carry whitout be injured.
The main reason that leads me to ask for help with the construction of these devices is that they are are tooooooo expensive and difficult to get in my country (Argentina), you have to import them, and I think I can do it Some devices here, not for Sale, Only For use in some research projects.
this do not happend in Argentina.
If you want to speak about birds i be placed to do it, but this is not the correct forum.
Clarified this and back to the post
¿What do you think of arduino to make a gps device as i want? I need to do the smalest one that i can.
Again i'm sorry for my horrible english.