Developing dataloggers can be technically a challenging task, only taking the size into account. Used in free nature, with no possibilities of perfoming updates, upgrades or replacements complicates the process. It is getting no better when the outside conditions get unsuitable even for the nature itself. But sometimes even we get surprised by our loggers. From 2022, three juvenile Bearded Vultures Gypaetus barbatus were fitted with our 33-gram models in the beautifull and montanious Armenia. The birds have grown and local specialists will surely publish separate papers on them. Here we present short summary of the devices they have been carrying on their backs.
90% of Armenia's territory consist of mountains. The Bearded Vulture is a species inhabitating montanious regions, above the forest border. Only these two information suggest how little chance there is for a tiny electronic device to operate properly. Diving deeper does not help much - mountains in winter can be beautiful, but the temperatures are freezingly low. Large birds means long feathers, so also bigger chance for covering the device's solar panel. Unlike other manufacturers, the Aquila loggers were design to minimize the negative impact on bird's aerodynamics - meaning no so-called "elevated panels" - obligatory solution to sustain the power of their devices. In Aquila loggers other implemented solutions have prooved succesfull over the years.
The devices used in Armenia are a great example for that. Up til now all three loggers have been operating without problems, consistently registering data at 20 minutes interval for 4, 3, and 2 years respectively. What lays outside our competences is the mobile network coverage. As expected, mountains do not support propagation of the mobile telephony's waves, which is used for transmission. With time, by this data registration's interval, considerable amount of unsent data had been stored in the devices' internal memmory. That is why last year the transmission interval was increased. What is striking is the fact, that it was done in least suitable time of year - at winter. The winter, the mountains, the minus temperatures, the unsufficient amount of sun light, the large birds with their long feathers, the poor mobile network coverage - ideal ingredience for shutting down a tiny electronic device. But not this time. It turned out the loggers have perfectly coped through all these obstacles. The transmission interval could have been gradually reduced to even every hour. With this settings the loggers have managed to transmittthousands of datasets, clearing their memmory. Worth mentioning is here the fact, that most such devices of this kind stop operating after after 4 years even in suitable, sunny and warm regions.
As for conditions where the Armenian birds with our dataloggers spent their time - 6317 datasets collected between 01st of November 2025 and 28th of February 2026 registered the altitude from 300 to 5400 meters asl, of which 124 below 1000 m asl, whereas almost the half were over 2000 meters asl. In these conditions the loggers have collected data every 20 minutes, trying sending them each hour. The battery was never under 95% charge level in neither of the three devices. The temperature was not registered in these models, nevertheless it is hard to expect some plus temperatures, considering the elevation and time of year. Apart from these 6000 datasets, the loggers also transferred another 6000 of stored ones. For the transmission local mobile operator was used - a standard feature of our dataloggers that enables avoiding high roaming costs.
This example prooves Aquila loggers are particularly effective in regions and circumstances which no other manufacturer can handle. Over the years we have had many other cases documented during research on White-tailed Eagles Haliaeetus albicilla, Imperial Eagles Aquila heliaca or Steppe Eagles Aquila nipalensis. On several occasions our loggers were capable to operate after laying covered by winter's deep snow layer (unfortunately the birds had died in autumn), and the record holder is one case of fully operating device in -40 Celsius degrees.
The movement of the two of the above described Bearded Vultures can be followed on our main portal's page, without the necessity of logging on.