What are the power requirements for something like that? Since the stations are much less densely distributed than cell towers I'd expect you'd have to use a lot more energy transmitting if you'd hope to get any data. This needs to be light enough to attach to an eagle.
There are APRS transmitters built for balloons that are not much bigger than a matchbox. It's all line-of-sight at the VHF frequencies and you can get quite a good distance on a surprisingly low amount of power. 50 miles on 200mW what's is doable, longer range on less power is not uncommon if the conditionss are in your favour.
