History of Ushichka

Pre Ushichka: waterside disasters

Ushichka was collected as part of my PhD thesis on how groups of echolocating bats manage to fly and echolocate together. Suggested by my supervisor Holger R Goerlitz, I wrote a grant based on the idea and won a DAAD stipend to see it through at the MPI for Ornithology, Seewiesen. The broad idea was that the PhD would have equal amounts of modelling and experimental data on echolocation in groups. The modelling work got off to a start early on. The experimental work ... well well. Equipment took forever to arrive - specifically the three 'fast' 25 Hz cameras.

For most of 2015-2017 I spent an inordinate amount of time looking for ponds where groups of bats actually flew together in groups reliably. Most of that time was spent by the shores of small lakes and ponds in southern Bayern. Holger's original idea was to get small groups of Daubenton's bats or pipistrelles as they flew above the water surface catching insects.

Many thousands of hours of cold summer and autumn nights, a couple of wet drones, and frozen fingers later I slowly began to realise that there were never more than 2 bats flying together. It was convenient that too many bats didn't fly together, but when your PhD is on how groups of bats manage to echolocate together - not much fun....

One thing did happen though, I got a lot of practise collecting data. Video calibrations, microphone setups and the single key point, automating data collection based on audio levels. All thanks to a suggestion by Daniel Lewanzik who'd seen something similar in one of Lutz Wiegrebe's setup! Sometime around 2017 I'd gotten an automatic triggering system setup - which meant a lot of the focus could go on setting up the equipment, sitting around for half an hour to check if everything was okay, and then going to lie down till battery change (not much of a field sleeper).

The recording rig behind Ushichka

Having worked with a similar audio-video rig before in Bristol, Holger knew some of the challenges of such systems. When using multiple cameras - each of the cameras need to sync'ed. The camera and microphones too needed to be sync'ed. Instead of doing it all with separate signals - Holger's idea was to create one common sync to trigger all cameras and audio recording at one shot.

The thermal cameras were thus set to run in sync with a 25 Hz signal, so they'd be frame synchronised. When recordings were triggered, the incoming audio buffers would be collected into a file, just as all three cameras captured video data. Thanks to the inbuilt sync'ing in the recording rig - much work is spared!

The system worked well in the lab when plugged into mains power. However, when run on batteries the audio data had a decent amount of multi-harmonic electrical noise...yes...all thanks to the DC-AC converter we were using. This made the rig very field incompatible for a decent amount of time. A few DC-AC converters later, and the problem still remained, and so we finally then moved to using audio-interfaces that could be fed with DC power directly.

Bear cave and onwards

Ushichka the dataset

The Ushichka dataset itself was collected during fieldwork conducted at Orlova Chuka cave in the summer of 2018. I was joined in data collection first by Aditya Krishna and then Neetash Mysuru Rajagopalachari.

• Thejasvi Beleyur